Updated 03/20/2014 

Coordinated Frequencies in Tucson 224.74 / 223.14 pl 136.5

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For the MSR2000 conversion web-site click here.

  Quick links  for the Micor conversion.  Receiver, Exciter (TLD5803b), PA, Duplexers, TFD6112A , TFD5102A , Echostation Interface

"If you build it they will come." de n1dhs

This is a HOW TO article and work in progress on the Motorola Micor repeater, 100 watt continuous duty HH (high band) VHF to 220 MHz conversion. It is my intention to document the conversion of this repeater to the 220 MHz band for amateur radio use.  I would also like to thank my good friends Craig kd7txo and John wd7f for offering their expertise to this project. For more information on the B.A.R.T. Group click here. de k7iou

 The repeater arrived!  micor repeater.jpg (200404 bytes)  micor repeater 2.jpg (166133 bytes)  Craig (kd7txo) and I (k7iou) unloaded it and stowed it in the garage. The next step is to inventory all the parts, options, and to check the operation of the repeater. Once operational, specifications will be checked and recorded per Kevin K. Custer and his article on the Micor 220 MHz conversion @  repeater-builder web site.

5/21/05 Plugged it in today and it went into transmit. 65 watts. Did some basic checks, settings on the squelch gate card etc. Still goes into transmit. 


RX TLD5784A 162-174







5/22/05 Played with the transmit problem today. I reverted the squelch gate card to the RT station (straight repeater). Replaced the cut jumpers on JU5, JU6, JU11, and JU12. Replaced the card and still transmitted upon applying 120V. I then removed the F1 card and saw JU3 had also been cut. The schematic said "line PTT". Since there was no explanation why this was cut I replaced it. Reinstalled the card and repeater still went into transmit upon applying 120V. I pulled the squelch gate card. Applied 120V with no TX and started playing with the squelch with the PL disabled. I could now hear the receiver. Then I applied the PTT switch on the Station Control card and the repeater transmits. While transmitting into the dummy load I then tried the power level adjustment on the PA and could adjust the TX from 0 watts through 65 watts. So I think the Squelch Gate card is bad. One of the reasons I suspect this is because after I tried it I pulled the card and found the white wire from JU15 plugged into the (0) delay jumper. So possibly a diode or transistor is shorted causing the PTT problem.

5/25/05 Removed the squelch gate card and did some basic checks on the transistors. Lifted base on Q6 and checked, ok. Pulled Q13, Q14 and checked, ok. I had pulled these thinking they may have been bad due to a wrong jumper setting before installing. Went back to my "gut" feeling that Q17 was the culprit. Pulled Q17 and checked, shorted across all 3 legs. Replaced, and transmit problem was solved. The only other problem I noticed was with JU15 in PL and I turn the repeater squelch counter clockwise until it keys the PTT the repeater won't un-key when I turn repeater squelch clockwise. I have to manually slide the PTT switch to key, un-key, and the repeater drops. May be due to the repeater looking for the tone on PTT? Will check later.

  6/1/05 Bill Jorden (k7ki) AZ. 220 MHz Coordinator faxed a copy of the approved coordination for the frequencies above. Thanks Bill.

  6/2/05 Tested the time-out timer today, works fine. Also worked on the test meter and the rotary control was stiff and the plastic knob was cracked and slipping. Took the meter apart, lubed the index and cleaned the contacts. Glued the cracked knob back together and reassembled. We are scheduled for Friday night to test the repeater with the Marconi. We will check for proper operation, then set up the receiver, transmitter, PA, tones etc. Once this is complete and all functions are verified it will be conversion time!

6/3/05 Craig (kd7txo) and I (k7iou) put the Marconi on the Micor and this is what we found. By-passed the duplexers and the TX was 90 watts. Through the duplexers 62 watts. Checked the CTCSS tone of 136.5, inoperative. Aligned the receiver, L101 didn't seem to have much affect. The peak wasn't as sharp as the other tuning capacitors. Did the typical receiver readings. Test position 3 was 25 uA instead of 15 uA. Test position 4 was 0, spec was 0. Test position 5 was high also spec was 1 or less. The receiver has a hiss. We could not locate the source of the hiss but this is what we found. On a car 10' away and the repeater into a dummy load, we transmitted voice audio and a tone.  On the car transceiver the hiss could be heard. We then pulled the Squelch gate card. 90% of the hiss disappeared. This unit was pulled from service because of problems. Looks like we are finding them. We will located another squelch gate card and try it.

DSC_0060.jpg (68769 bytes) k7iou & kd7txo with the Micor project.

6/7/05 Last night we stowed 2 more of these repeaters in the garage. I took the squelch gate card from one and checked the jumper settings. Installed it in the original repeater and the receiver noise disappeared. So we are good to go for the 220 MHz conversion on this unit. The second repeater I went to test it and the power supply is bad. Will check it later. I found out that this unit was in service and they had a power failure. Since it had a battery back-up I think it took a power surge.

Also there are 2 schools of though on converting this to amateur radio. One school is to leave the cards in place, modify the squelch gate card for the controller. The 2nd school of thought is you remove all the cards except the station control module and hook your repeater controller directly to the pins on the backplane. After consideration and recommendations I am leaning towards the 2nd school of thought.

Worked on the 2nd repeater today. Found a white powder in the 15 amp fuse holder for the power supply. When we got this the volume control was full clockwise, squelch un-squelched full counter clockwise and the meter on "exciter". I think when the unit took a power outage the fuse blew? Hence the white powder. Possibly it was checked, a fuse replaced but due to the residue the circuit wasn't completed. Her is a pic of this beauty. 2ndrepeater.jpg (202059 bytes) Now operational!

6/8/05 Special thanks to Tom ab7ic for offering to purchase a new G7-220 antenna for the project. Way to go Tom!

  6 /11/05 Research, research, research! Took apart a duplexer today. This is far as I got it without surgery. duplexer.jpg (185319 bytes) more duplexer pictures after surgery, 2, 3, 4, 5, 6, 7, 8, & 9. I read a very fine article on Repeater Builders web-site on Duplexer theory by Jacques ve2azx. Theory and Testing of Duplexers. Jacques is working with us on converting the existing high band VHF duplexers to 224 MHz. This is the graph duplexergraph.jpg (105398 bytes) Jacques sent me. I would like to thank him for his knowledge, expertise and time. de k7iou

Been looking at power modules and the idea of running 2 of them. 30 watts each. This is one that I'm considering using. Model # RA30H2127M, Frequency range 210-270,  12.5 V , 30 Watts,  40% Efficiency,  50 mW drive,  H2 design. Check it out at  RF Parts. I also saw talk of a Wilkinson divider on Repeater Builders. I would like to thank Gary nz5v for sending it and explaining its construction. "A Wilkinson power divider is just a standard 75 ohm 1/4w phasing harness with a special modification... a NON-INDUCTIVE 100 ohm power resistor across the center conductor of the two output ports.  Be sure the 75 ohm cable is a 1/4 wave at the transmitter frequency...  remember the MFJ is 50 ohms and you have to correct for it, or since I have an HP S-parameter 75 ohm test set, I can use the vector display on the network analyzer to "measure" 90 degrees at the desired frequency." wilkpowerdivider.jpg (25748 bytes) 

  6/12/05 John (wd7f) and I worked on the tone problem today. We checked all the jumper settings on the F1/PL card, and the Squelch gate card. Set them for PL. Transmitter wouldn't key with the tone from the Marconi. John took the schematic and used his "intellectualism" and discovered that there was no PL indicator coming from pin 14, or PL indication coming from pin 4 on the card. He followed the circuit on the backplane and discovered there was nothing connected to the circuit. We discussed the possibility of another card controlling it also. I dug threw a box and found a Code detector card. I inserted it, tested the receiver with the Marconi and Walla! We now have a working tone on the input. I also aligned the receiver, and the exciter today. Everything looks good. Will be starting on to the 220 MHz modifications this week!

  6/13/05 Pulled the RF/IF board today. Then removed the RF preselector. rfpreselector.jpg (325317 bytes) 

  6/14/05 Removed L 102 and L 103 and modified them for 220 MHz. L102.jpg (89808 bytes) L105.jpg (134665 bytes) modified pre-selector preselectormod.jpg (327888 bytes)

Ordered the Crystals today from Bomar as they were recommended by Scott Zimmerman (n3xcc) of Repeater Builders. He said, "we have been using Bomar for the past few years because of some quality issues with JAN. The other reason is that Bomar will temperature compensate the crystals for a reasonable fee. Jan will not temperature compensate at all." The crystal cost is $25 each plus $10 shipping UPS. Total cost of $60. Receive 223.14 KC1005/12 Transmit 224.74 KXN1019/18. I will keep you informed on the quality and service from Bomar.

RF/IF board receiver.jpg (418988 bytes) and the area of modification Receiver2.jpg (578803 bytes) enlarge and look close for parts I.D.

  6/15/05 Purchased most of the components (caps) from Elliot Electronic Supply in Tucson today. Was short (4) from the parts list. Will have to locate from another source. Converted the duplexer to chassis "N" connectors for testing.  Notice the small hole between each chassis "N" connectors. This is the access for the capacitor adjustment on the "notch" stub. Craig kd7txo picked this beauty up this am for testing. He will check the notch and the resonance frequency.

  modduplexer.jpg (236313 bytes) Pulled the exciter today and we have a different model. TLD5803B tld5803b.jpg (1881517 bytes) tld5803b1.jpg (825914 bytes) tld5803b2.jpg (214822 bytes)

  6/16/05 Craig (kd7txo) played with a duplexer today. This is what he got with the initial test. Passes at: 201.75 MHz the top left hump, reject at: 204.67 MHz Span of : 2.83 MHz,  with -43 db rejection, from peak to valley. Insertion loss of: -3.3 db. More work needed.

 dupspecan1.jpg (72602 bytes) dupspecan2.jpg (64130 bytes)

  6/17/05 Craig (kd7txo) played with the duplexer again.  "Today after some playing with the cap and adjusting I got an
insertion loss of: -0.5db ( 1/2 db loss ! )  Which is real good! The Max to
Min displayed is 1.635 MHz with 43 db isolation measured with the Spec AN.
This makes me a lot more hopeful that there may be a solution. We're
definitely not out of the woods but it looks much better." de kd7txo

dupspecan3.jpg (70275 bytes) dupspecan4.jpg (60822 bytes)

  6/18/05 A BIG special Thank You to Larry wa4fob  of Magnolia KY for emailing the schematic on the TLD8262B exciter. 

  6/19/05 John (wd7f) came by today and worked with the schematics from the TLD8262B and compared it to our TLD5803B. He worked up a conversion for the 220 MHz conversion so to speak. For the conversion of the TLD5803B. We will give it a go when we get the crystals from Bomar and try the alignment of the exciter. He also looked at the PA and the power module specifications. He thinks possibly we can make the SWR / power fold-back protection work also. He borrowed the manual and thought maybe he would have a "epiphany or something" if he studied it hard enough. 

  6/22/05 John (wd7f) and I (k7iou) tore into the PA today. First we removed the assembly from the rack.  Then we removed the input bracket and cable assembly,  power set board, harmonic low-pass filter, lowpassfilter.jpg (147199 bytes) and the 100 watt PA board, (don't forget to un-solder the power connections for the feed through capacitors before removal on the red and black wires where they feed through the board). I then ground down, filed, sanded off the raised bosses for the power transistors on the heat sink. I would like to direct mount the power modules to the heat sink. heatsink.jpg (214872 bytes) 

Also removed the helical band-pass filter from the exciter location. helicalbandpassfilter.jpg (175556 bytes) Then I modified the harmonic low-pass filter. I cut 1 turn out of each coil & re-soldered. modifiedlowpassfilter.jpg (115446 bytes) (note; this mod in this picture is incorrect). I tested the filter and it didn't pass the proper frequency. I went back to repeater-builders web site and re-checked the modification instructions. At the bottom of the page there was a obscure link and then I found this. harmonic.gif (61911 bytes) So be careful on this modification as the instructions call for 1 turn out of every coil to be removed. But according to the .gif above L1 @ L6 is only 1/2 turn and L2 through L5 remove 1 turn. So I repaired the 2 coils to 1/2 turn only and then checked the filter. Its still rejecting the frequencies up at 220 MHz. Craig kd7txo will take it and play with it with his equipment to see if he can solve the 90% loss problem. 

  6/24/05 Worked on the TFD6102A harmonic low pass filter today. I made up a test cable with a RCA and a PL259 on each end. Assembled the filter in the case and re-tested. On low power into a antenna and through my Bird watt meter it passed 4 watts, on high power it did 20 watts. I then removed the filter and connected the radio (IC-37A) direct to the Bird. It did 5 watts on low and 19 watts on high. So I think we are in the ball park. I believe the problems occurred during the original testing after the correct mod was done due to not having the cover installed. The cover has cavities-shields built into it for RF reasons. The second problem was the cable I was using had alligator clips instead of the RCA connector. 

Craig (kd7txo), John (wd7f) and I worked  late into the evening on the duplexer. We unsoldered the internal had and cut 1/2" off it and retested with the Spec An and Marconi. The specs went crazy. I then had a epiphany and discovered that its relationship to the dual loops are important. So  we enlarged the hole in the top of the hat so it would slide down the internal tube 1/2 "from the end of the tube and retested it. The frequency moved up to about 218 MHz. We started about 8 pm and called it a night at 11:30 pm.

  6/25/05 I (k7iou) worked on the duplexer today. Cut the internal hat another 1/8" and retested. the frequency moved to 224 MHz. I cut another 1/8" and retested. It went to 228 MHz. I then soldered it back on the tub at 3/4" up into the cavity from the end of the tube. Retested again. Was on 229 MHz. I then took a piece of 3/8" copper tubing inserted into the top of the duplexer (where the adjustment rod was) and found with a 1 1/2" protruding out the end of the tube into the cavity the frequency dropped to 224 MHz. I then removed the copper tubing and reinstalled the fine adjustment shaft and retested. The frequency lowered approximately 1 MHz.  I then cut some copper tubing 1 1/2" long and inserted on the end of the shaft and retested. The frequency moved to far. I tried 1" and it went to far the other way. I found 1 1/4" was perfect and adjusted the fine tuning on the shaft for 224.74 MHz. I then called it a afternoon. I thought about this adjustment later that evening and think I'll try using home made washers and clip them on the end of the shaft with the original clip. Testing of this will follow.

Special thanks to Keith (kr7rk) for donating to the project a Communications Specialists TP-3200 controller! Found their web site Com-Spec and downloaded the software and manual.

tp3200e.jpg (11205 bytes) Thanks Keith!

  6/26/05 John (wd7f) and I (k7iou) played with the duplexer today. I cut several copper washers to achieve the desired pass frequency. Our preliminary test show this is going to work with about 38 dB. Which will be fine with a 1.6 MHz separation. I will give it to Craig (kd7txo) for the final tweaking on his spare time at work. I will ask if he can test it with power / load. Setup2.jpg (148617 bytes) Notch1.jpg (57208 bytes)

  6/27/05 Got this from a admirer and couldn't resist posting it. "wow what a whippin, I did a Micor to 220 about 10 yrs ago.... still have sleepless nights over that one" de kb5wb

  6/28/05 Ran a power test on the duplexer today. My IC-37A through the Bird meter into a dummy load, 23 Watts. Next ran the IC-37A into the modified duplexer, into the Bird meter and the dummy load, 20.5 - 21 Watts. Wow, less than .49 dB loss. I then Put the IC-37A in (- duplex) and keyed the PTT to check the reject frequency (223.14 MHz)  0 Watts out! Ye Ha! Almost home on these. In about 3 weeks we will modify the rest of them. de k7iou

  6/29/05 Got the power modules yesterday. John (wd7f) came down and we combined our brains and came out with this layout. dualpa.jpg (687177 bytes) Dug into some boxes of old gear and pulled out several junction strips. I did some drilling and taping on the heat sink and behold our initial layout.  I also modified the exciter band pass filter TFD6112A per the Micor mobile instructions on the repeater-builder web site. I tested it and had a 4.77 dB loss. No-go on the filter. Need to adjust the slugs but Motorola used some type of epoxy and glued them in place. Tried chipping, dissolving the stuff with no luck. Another day on the filter.  de k7iou


  6/30/05 WD7F's proposed PA Schematic PAschematic2.jpg (20120 bytes) Note: we didn't use this design, check the PA link at the top of the page. UPS delivered the Hustler G7 220 MHz antenna today. Thanks Tom!

  7/01/05  I modified the exciter helical band pass filter TFD6112A. John wd7f came down and we tuned it. Ended up with 1.02 dB loss on 224.74 MHz! If you have one out of a repeater station the slugs are glued in place with epoxy. I couldn't loosen up the epoxy enough and the slug tool slots were stripping out. John (wd7f) came up with some coil forms. For instructions  on the TFD6112A hbpfilter4.jpg (63095 bytes)

Also adjusted the PA pass band filter TFD5102A today .23 dB loss! Pretty darn good if I have to say myself. papassfilter1.jpg (284238 bytes) papassfilter4.jpg (185493 bytes)

  7/02/05 The crystals showed up last night. Installed them in the elements. Very simple process. Use a small screwdriver and push out the 2 indents on the sides of the metal cover. Pull cover off, remove rubber cushion on end, remove plastic envelope. Unsolder crystal. Solder in new crystal. Install plastic envelope, and rubber cushion. Straighten out indent in metal cover and reinstall. Indent cover to secure and mark cover with new frequency. I used white out and cover old frequency and a pen to write in the new frequency. I also cut out the specs on the envelope Bomar sent and taped it to the cover. elements.jpg (139072 bytes) elements2.jpg (87037 bytes)

A very special thank you to Larry wa4fob  of Magnolia KY for mailing the capacitors we needed and couldn't locate.  This is what ham radio is all about. 

  7/02/05 We had a antenna assembling party today. Tom ab7ic got a pass from the war department. John wd7f and I tried to help also. Way to go Tom!

ab7ic3.jpg (68777 bytes) ab7ic_k7iou.jpg (72646 bytes) ab7ic2.jpg (73024 bytes) 

  7/05/05 Finished installing the capacitors in the receiver and exciter today. Then reinstalled them in the machine. Just need the Marconi to align and set them up.

220receiver1.jpg (358508 bytes)

  7/014/05 Started the alignment of the receiver but need the Marconi. The exciter is a different story as it wouldn't align properly. Off to the bench with the Spec-An. We will review the 220 MHz modification and updates will follow.

  7/015/05 Special thank you to Tom (ab7ic) for purchasing the "N" chassis connectors for or duplexer project. We found some locally at Elliot's Electronic supply. Amphenol 203/743-9272 $3.30 each.

Craig, John and I had a repeater session. We hooked up the exciter on the bench with a 12V & 9.6V power supply. And did some basic checks. Didn't resolve anything but we learned allot. exciterbench1.jpg (204157 bytes) exciterbench2.jpg (396352 bytes) exciterbench3.jpg (184791 bytes) exciterpeak4.jpg (138551 bytes)

  7/16/05 Went to Elliot Electronic Supply after the BART breakfast and loaded up on some capacitors.

7/17/05 John and I aligned the receiver today. Worked fine. We were thrown for a loop though for a few minutes as we were on a second peak on some of the adjustments. Tested the receive with the 220 rig in the mobile. Sounded good. Craig also came by and we played with the exciter some more. John and Craig worked out the math craigjohnmath.jpg (186121 bytes) and got the tripler working and we are getting close. davecraigjohn.jpg (139280 bytes) Maybe another night and we should have it working. We temporally solder some capacitors to the back side of the board for testing. 

  7/29/05 Been working on the exciter. We got about 180 Mw out of it with the wd7f conversion. We do have a problem as it starts dropping off on the Mw as it warms up, and stabilizes about 114 Mw. The TX crystal also is low on frequency. Its was running at about 224.55 and with a capacitor change (in the element) directly behind the 3.5 pf adjustable capacitor is only came up to 224.58. It had a 27 pf npo and tried a 22 pf npo with not much change. Then tried a 18 pf npo and it increased to 224.58  So we are going to send this back to Bomar with the element since the frequency is low.

n7kp writes "Just want to thank you folks for your "how to" articles on your 220 MHz Micor conversion." Thanks, de k7iou!

  7/30/05 wd7f and I worked on the exciter today. Took a can of cold spray and isolated Q406. When we hit it with the cold spray and it  jumped up to around 250 Mw. Replaced Q406 (M9390) with a mil spec (2N2222z) metal transistor. Then tested the exciter. It went close to the 300 Mw range. So we took all the caps and resistors and returned them to the component side of the board. We tested each one separately after we moved them. By the time we were done we had 368 Mw out of the exciter. This showed us the Mw loss with components mounted on the solder side of the board. So the wd7f conversion is good to go. kd7txo came by and checked the 450 MHz harmonics with the Marconi. DSC_0001_2.jpg (95721 bytes)  DSC_0002_2.jpg (92709 bytes) For our exciter conversion TLD5803b

  8/13/05 Last night and today wd7f and I (k7iou) spent about 4 hours combined working on the PA with the dual modules. I had previously cut and installed the perf board on 4 studs with risers and star washers. I bent the wire connections on the modules 90* to extend through the board. I extended the power and grounds to extend through the perf board also. We installed the capacitors and wired the assembly. Used a piece of 3M body side molding tape to install the TU-50 power divider. The input (TU-50) will extend through the shield for the SMA connector from the exciter. dualpa.jpg (687177 bytes) dualpa2.jpg (891323 bytes) We need to make the Wilkinson power combiner and test the gate voltage. Bomar shipped the TX crystal back to us and we should have it soon. They confirmed it was off frequency.

  8/15/05 A special BIG Thank You to Steve N7KP for donating a TLD8262B exciter and TFD611A filter. I wanted to experiment with the exciter and needed another filter for the 2nd conversion. Thanks Steve!

  8/16/05 Got the crystal back from Bomar today. Its on frequency, 224.74 MHz. Don't understand why they send them UPS orange when US Priority mail is faster and cheaper?????? It took 2 days for priority mail on the shipping of the crystal to Bomar and 7 days return including the weekend for UPS. 

  8/21/05 Last Friday night kd6txo, wd7f and I (k7iou) worked on the pa. solderingpa.jpg (76927 bytes) We tested the modules separately and had 31 -34 watts out of each. We also restricted the output of the exciter with a 180 ohm resistor at R436 for 110 mW output. We then worked on the pa power combiner for both modules. Our design doesn't seem to be doing the trick, so back to the drawing board. patest.jpg (371644 bytes) patest2.jpg (370650 bytes)

  8/24/05 Craig (kd7txo) called last night. He talked to Stanly (wa7wnm) about our Wilkinson combiner. Seems Stanly thinks ours isn't working because we aren't using phase stable cable like RG-400 or heliax. Stanly also suggested a better design for the 2 modules using phase stable cable, 50 ohm, and a 5 watt dummy load. You build a bridge with the output at 12 o'clock, the modules at 3 o'clock and 9 o'clock. At 6 o'clock is the dummy load. The cables are cut as follows: from the dummy load clockwise to module 1 (9 o'clock) cut it @ 90, from module 1 to the output,90, from the output to module 2 90, from module 2 to the dummy load 270 (yes 270). This design gives you protection in case one of the modules goes caput. He also recommended BNC connectors with T's at all the junctions. This way all the cables could be cut accurately.  We will try this one in a week or two. de k7iou

10/8/05 Well its been to long since an update. Success today with the PA! The new job, vacations, school, business and the family kept us until today from  working on the project. Craig (kd7txo) and John (wd7f) built some cables today. Craig had previously built the bridge. I worked on brackets and cleaning up the PA today. Then the 3 of us went to work. As you can see by the pictures we did it! pabridge.jpg (69347 bytes) pabridge2.jpg (89093 bytes) pabridge3.jpg (80709 bytes) pabridge4.jpg (67796 bytes) pabridge5.jpg (70037 bytes) pabridge6.jpg (40394 bytes)

We had many attempts and failures trying to combine the 2 modules. The 73 watts is out of the PA harmonic filter. We got rid of the perf. board and directly mounted everything to the heat sink. Bonding was a issue so we bonded each base of the modules. I will post the PA design and instructions at a later date. Special thanks to Craig, John, and our wives and families for putting up with our mess and hobby time! de k7iou

  10/25/05 Well we had a productive couple of days last weekend. Saturday wd7f and I worked on the PA and got the power set and SWR protection wired up. John came up with 2 - 4.7k ohm resistors to lower the gate voltage and we tapped them in the middle for the correct voltage. We adjusted the watts with the power set for 55 watts and I tested the SWR protection. I disconnected the dummy load and momentarily keyed the PTT. The power out dropped to 18 watts. We will play with this later to see if we can get it to go to 0 watts. We used the repeater for about an hour Saturday and it quit transmitting. I checked the gate voltage and it was 0. I suspected the exciter and pulled it for a check. I found a cap bent over and touching pin 15. It ran us around for about 5-6 hours and finally I was pushing on the exciter and it took off. So Sunday I tried an original exciter at 172 MHz and it worked fine. I took the 220 MHz exciter and went to the bench with a magnifying glass. I touched up some traces and joints and its been working since. I also checked the controller with the software. I have to admit the software isn't user friendly as its in DOS. But we were able to program it. For instructions and pictures of the PA we built <click here>.

  10/28/05 John (wd7f) and I (k7iou) worked on the controller today. John wired up the squelch gate card Controller1.jpg (297155 bytes) as you can see in the picture. We tried to cut the controller into the back plane but our version of repeater had no discriminator audio on the back. So for ease we decided to do the squelch gate card method. Here is a picture of the repeater with the controller attached and running. controller3.jpg (216100 bytes) more to follow, de k7iou

  11/05/05 John (wd7f) and I have been trying to program the controller for several weeks as the carrier delay wouldn't go below 3 seconds. I emailed Com-Spec and they replied I had to have it in the tone squelch mode. When I did this the PTT would drop intermittently and some tones would work and others wouldn't. I took it out of the tone squelch mode and we lost the CW id. It went to Morse code heaven and was never seen again. So the process began looking for another controller. I wanted a RC-110 kit but they are out of stock until the first of the year. So we were looking at the RC-210. Its a Cadillac of controllers but was out of our price range in the factory built model. So we were considering the kit form at $250. Then John found Echo Station http://www.synergenics.com/sc/  Its a windows based computer program that lets you use a computer as a controller. It has a voice synthesizer so you can add recorded wave files. So we are currently using this on Windows 2000 Pro. The audio is similar to Echolink as its not the best, but it is ok. We will be using this until we get the controller kit assembled and hooked up. We will post the interface we made on the quick links above. de k7iou

  12/9/05 Sorry for the delay in updates. Had a problem with Comcast and had to rework this site as it was full to the maximum limit.

 Ordered the new controller kit. Yes I decided to save the $100 and build it myself. WHY? Because it is fun and challenging! I don't like being an appliance operator. You know, plug and play devices. I ordered the kit from Arcom. Ken is very helpful in assisting you with any of their products. I highly recommend Arcom. This was the first evening of building rc210r.jpg (435694 bytes) the second evening rc2102r.jpg (492234 bytes) the third day, (Saturday) about 4 hours rc2103r.jpg (419034 bytes) rc2104r.jpg (414902 bytes)  I found this fun to build. The assembly manual is very good. In all it took me about 8 hours. I did double check all resistors for proper resistance and used a magnifying glass to id all components. Ken even has a email reflector which you can join for questions and comments.

I also finished converting the duplexers. See the quick links above for the conversion. On Saturday 12/3/05 kd7txo, wd7f and I (k7iou) went down to Craig's (kd7txo) work and cut in the cables for the duplexers. We used Jacques ve2azx for more info on cutting the cables. He sent me this in a .pdf file which I converted to jpg. coax.jpg (102779 bytes) coax2.jpg (182883 bytes) coax3.jpg (197126 bytes) coax4.jpg (205991 bytes) coax5.jpg (224590 bytes) coax6.jpg (123709 bytes) We used the formula's for cutting the cables. This took about 4 hours and we did a quick adjustment of the pairs. We got 58 db isolation out of the receive side and 52 db isolation out of the transmit side. We used a Vector volt meter a Marconi and a HP Spec-an. We will try to peak these after the antenna is up during the final tune up of the repeater. 

I also noticed a problem with the repeater in the early AM with my drive to work. The receive was horrible, Couldn't key it from 1 mile away, but in the afternoon it was good 25 miles away. I played with the squelch and the receiver alignment and all is well again. 

Here are some pictures John wd7f took of the duplexers after we got done with them.  duplexerpk6.jpg (102498 bytes) duplexerpk1.jpg (82042 bytes) duplexerpk2.jpg (105433 bytes) duplexerpk3.jpg (105342 bytes) duplexerpk4.jpg (82770 bytes) duplexerpk5.jpg (124526 bytes) John and I checked the loss on transmit. We had 50 watts into the duplexers and 42 watts out @ 0.75 loss. Pretty darn good if I have to say so. 


  12/11/05 ANTENNA PARTYI decided to put the 220 MHz Hustler antenna on the tower behind the garage and to move the repeater to the back of the garage. I prepared the tower for lowering and John wd7f came by to help and to take all the pictures. Later Craig kd7txo and son Clint came by to lend a helping hand. Thanks guys! Here is a picture of the winch I used to lower the tower winch.jpg (174354 bytes) and the lowered tower, notice the vertical pipe with a pulley in the top. tower2.jpg (148048 bytes) Dave removing the 5 antennas. tower3.jpg (134569 bytes) tower4.jpg (142995 bytes)  view of the tower from the end. tower5.jpg (177129 bytes) Moving the repeater. tower6.jpg (100311 bytes)  The hustler goes on. tower7.jpg (78455 bytes) Add on the surge control box with the Polyphaser. tower8.jpg (121932 bytes) Craig and Dave adding the coax. tower9.jpg (165387 bytes) Craig finishing the connection. tower10.jpg (85400 bytes)  Supervisor "Clint" of antenna installations. tower11.jpg (64617 bytes) Ah up in the air! tower12.jpg (26736 bytes)  The back view. tower13.jpg (105861 bytes) Whew! 45' to the base of the antenna. tower14.jpg (92217 bytes) 

  12/17/05 John (wd7f) and I (k7iou) tuned up the repeater today. We got a little more out of the receiver as a injected 1 KHz tone would disappear @ -106 dB.  "To align the deviation, we first injected a 1000 Hz tone at 3 KHz deviation into the receiver.  With the Repeater Level adjustment on the squelch gate card set to near maximum CW, we set the voltage at TP1 in the controller to 0.75 V Pk-Pk (0.265 RMX) using DISC1 in the controller.  Then we checked the exciter output and adjusted the deviation to 3 KHz with controller TX1. We found that the PL deviation was too high, approximately 1700 Hz, so we increased TX1 until we had 3.5 KHz deviation and then decreased it to 3.0 at the exciter IDC.  We repeated until we had about 1 KHz of PL deviation and the exciter deviation was linearly tracking the receiver input deviation from 1 KHz to 4 KHZ and at 5 KHz it rolled off to 4.5 KHz.  We noticed that the deviation was becoming non-linear at that point and didnt attempt to reduce the IDC and PL deviation  any more." de wd7f

A big Thank You to Bob (n7zqk) for donating a Motorola Service Monitor to the BART group! We used it for the tune up of the repeater today. motoservicemtr2.jpg (96896 bytes)

  12/20/05 Noticed during the tune up the other day L-104 on the pre-selector had a funny spot in it on adjustment. I believe this was the problem with the COR light on the controller also. We would loose the squelch and receiver when we hit this spot and the COR light would illuminate. Then the next morning the COR light was on again, so I tweaked it and the light went out. Returned home after a days work and it was on again. So I pulled the receiver and the pre-selector and L-104. I checked it and didn't see any problem. I went ahead and re-soldered the modification L102.jpg (89808 bytes) and reinstalled. I then retuned the receiver. The bad spot disappeared. The next day on the way to work the receiver didn't receive as good as before so today I retuned it again. This time after the alignment procedure I injected a 1000k tone at 3000k deviation into the receive duplexers and tweaked the pre-selectors until the tone audio passed through the speaker the best as possible without paying attention to the Motorola test meter. I also did this with L-108, 109, 110, 111. I kept lowering the injected signal (dB's/micro volts) as I tweaked the adjustments listening to the tone in the speaker. When I was done I had -115 dB's or .397 micro volts. This was as far down as the Marconi would inject the signal and still passing the tone! The true test will be in the AM on the drive to work. Will update the test results. de k7iou

  12/28/05 Ordered a preamp the other day. Its a P220VDG. Will let you know how it works. http://www.advancedreceiver.com/page5.html

  1/15/06 Got the preamp installed and it works great. Made a big improvement. got over -132 dBm sensitivity out of the receiver. Mounted it close to the receiver using 2 existing holes below the receiver. I also used a short bnc cable from the preamp to the receiver.

  1/22/06 Installed a fan on the PA. Its a nice squirrel cage type with a rotate able motor. I made a mounting plate out of scrap metal, used 2 existing screws and some 3M body side molding tape to secure it. A relay was used to control the 120v and 12v to supply the relay. The RC-210 uses the ground for control. Timing for the fan is set in the RC-210 program.  pafan.jpg (60184 bytes)

  7/20/06 Well we had problems with the duplexers again. Seems they just won't hold steady on the receive side with temperature variations. So Craig purchased a set off eBay. So Craig (kd7txo), John (wd7f) and I installed them last Saturday. We had to change some cables and ends but it seemed to go well. That was until Monday morning. There was a big problem with the receive. So Monday evening we got back together and re-tuned, tweaked and adjusted the deviation of all the systems including the links. Craig and John came up with a better way for tuning and it seems to have done the job. Here are some pictures. Special thanks to Tom (ab7ic), John (wd7f), Craig (kd7txo) for your donations! newdup.jpg (120369 bytes) newdup2.jpg (106034 bytes) newdup3.jpg (137157 bytes) newdup4.jpg (119918 bytes) and here are the specifications, wow! newtune2.jpg (76619 bytes) de k7iou.

  10/07/07 I have been lacking in my updates so here goes. The RC-210 controller has had some problems. I have a love / hate relationship with it. I love the features especially the L.E.D.'s as they let you see with a glance the operations in process. PTT, COS, DTMF. The hate part are the problems with the firmware. Especially the Time Out Timers with the ports running only links. They affected also the repeater port so if one link stayed PTT the repeater wouldn't time out causing a duty cycle test of our PA @ 100%. The good news is the PA has held in there like a champ. So I guess our design is a good one.

Next problem was the Bomar crystals. I had a problem with the TX side right out of the box and Bomar corrected it. Then after about 1 year of service the RX side started going low in frequency on us. I changed the element and it corrected it for awhile but 4 weeks ago I noticed DTMF was no longer being accepted. I tested the RX xtal and it was 10 kc low. I tried contacting Bomar about the crystal problem with no response. So I am no longer recommending them. I made a query on Motorola-Micor@yahoogroups.com and an overwhelming number of responses were to use ICM (International Crystal Manufacturing Co.) I mailed them 2 elements (1 as a back up) and 3 weeks later I received the crystal installed with a full compensation. Before you have your crystals made for any project please read this great article. http://www.repeater -builder. com/tech- info/temperature -compensation. html 

I received the new crystal from ICM and installed it in the receiver. All is working fine now. Audio is again crisp and clear and the DTMF is being accepted. Special thanks to Tom

  03/20/08 Its been awhile since I have done the updates so here goes. WD7F (John) and I (K7IOU) successfully adapted a CAT RLS-1000B to the Arcom RC-210 controller. We first actually designed and built an extra port but then I blew it by buying a IRLP embedded node. So we looked at the CAT and we both came to the conclusion that we couldn't build a 3 port switch for the price they sell the RLS1000B for. 

So here it is. repeater controller1_2.jpg (162443 bytes) Its working great and thanks to Craig KD7TXO for the loan of the Marconi and a 3rd set of hands for adjusting the audio on all the ports. The finished product. repeater controller1.jpg (166613 bytes) Here are some pictures of the V.O.I.P.'s Echolink Node.jpg (91309 bytes) IRLP Embedded Node.jpg (95664 bytes) Special thanks to WD7F for donating the monitor switch and AB7IC (Tom) for the cash donation. I still have some house cleaning to do but its all working A-OK. 73 de K7IOU

09/13/08 Last Thursday night we had a monsoon blow through town and on Friday the system started acting up. After playing with the controller for several hours re-flashing and loading the firmware I realized the problem was RF related when the link on the 146.940 was receiving. The controller started acting funny then the 224.740 transmitted when it shouldn't have causing the link to drop the receive and go into TX.  I also noticed while using the local microphone on the repeater the DTMF led and the COR lights would light up with an intermittent PTT on port 1. With the transmit switch off on the repeater the problem ceased. So I left it over night with the 224.740 repeater disabled but the links up and running with the voip's. This morning I decided to try my spare squelch gate card in the repeater and the problem disappeared. Knock on wood! I also redesigned the cart that holds the computers and moved the links to a shelf below the computers. Here is a recent picture of the system. 224.74repeater.jpg (133988 bytes) I would also like to thank Keith kr7rk for the donation KVM switch to the B.A.R.T. system. I am using it for the IRLP and Echolink computers which allows the use of one keyboard, monitor and mouse with both systems. Thanks Keith!

Contributors to the project
Tom ab7ic, Bob n7zqk, Craig kd7txo, John wd7f, Dave k7iou

Bart Repeater Fund    
Summery of activity    
Total funds donated 685.00  
Total Receipts $ 1241.88
Elliot Electronics 12.89  
RF Parts 119.05  
G7-220/donated/est 170.00  
RG-142 15.00  
Bomar Crystals 60.00  
Back-up battery/donated ?  
controller/donated ?  
Manual/donated ?  
Micor repeater/donated ?  
Capacitors wa4fob 10.00  
N chassis connectors/donated 31.96  
Elliot Electronics 5.00  
Anzac TU-50 23.00  
tld8262b donated n7kp ?  
tfd611a donated n7kp ?  
RC-210/software/shipping 288.95  
Elliot Electronics 64.46  
Elliot Electronics 5.70  
Elliot Electronics 11.09  
Elliot Electronics 5.86  
Elliot Electronics 14.42  
Elliot Electronics 15.49  
Radio Shack 6.42  
Duplexers from eBay 320.99  
Shipping 5.15  
ICM rx crystal 56.45  
Total Disbursements $ 1039.92
Balance Available $ -233.41

More to follow, so check back often.

Thanks to all.

de Dave k7iou

The following manual is a must; 68P81036E40-C Micormanual.jpg (318119 bytes)

Email the Webmaster:


Arcom  503-678-6182

Bomar Crystal Co. 1800-526-3935 No Longer Recommend them due to no response from the company

Channel Element Headquarters 1-800-237-9654

Computer Automation Technology  Controllers-Cat-250 & RLS-1000 

K7CC  B.A.R.T. Border Amateur Radio Team.

ICM  International Crystal Mfg Co. 1-800-725-1426

MSR-2000 Amateur Radio Conversion website by Dave k7iou

NKX, Inc. 1814 Hancock St.  Gretna, La. 70053  Talk to Pam at 504-361-5525

Radio Wrench; Kenwood Sales and Service. Skipp May

Repeater Builders; Scott Zimmerman and Kevin Custer

Squelch Gate Module to External Repeater Controller Conversion  Special thanks to Skipp for your help and expertise! 

WD7F Homepage