Receiver Page -
I've had a lot of great and not-so-great receivers over the years. A few examples include a Hammarlund PRO-310, Collins R-388 and a National HRO-500 with pre-selector. Additional receivers can be seen on the "Shack Pics" page. Shack Pics
Hammarlund PRO310 - this receiver is featured on the intro page to the website. It's quite unlike anything Hammarlund had done up to and since this was made back in the early 50's. There were less than 1000 made, mainly because they were too expensive for what they offered the average ham operator. It is an SP-600 that was commercialized. It has the same rugged turret tuning system as the SP-600 along with like structural integrity (and weight). The interesting case style was pure "retro"; but, things like knobs were designed almost as an afterthought. They are pretty flimsy. Another example was that the Hammarlund logo was put on the front panel with double-sided tape. That's why few remain attached.
Its a very nice AM receiver that takes advantage of a 6V6 for that rich, full sound. The dial system is unusual but quite accurate after you get the hang of it. The cylindrical dial reminds a person of the Gonset GSB-100 transmitter and the National NC-300 receiver. Unfortunately there are "1st generation" printed circuit boards in the rf stages of this dual conversion heavy-weight. Those first boards didn't have the expansion coefficients quite figured out so they constantly expand and contract, sometimes tearing "traces" apart. Its quite a receiver, though, and will always be in my collection.
For more detail, please visit Jim Garland's website, W8ZR. He really delves into this receiver and its workings as well as many other fine receivers. He has done a terrific job.
Collins - R388
This is my favorite Collins receiver. It has a great 1 khz dial readout and is as stable as it gets.
I put this into an old Heathkit Warrior/Apache/Mohawk case. Additionally I installed a 6.0 khz mechanical filter in the #1 Crystal Filter position. It was taken from a subchassis available from Fair Radio. There are consecutive ER magazine articles that I combined to guide in this installation.
I also take a sample of the audio output to one channel of the monitor scope as well as feed the audio tape deck for recording.
HRO - 500
National's last hurrah.
This is the HRO 500 along with the LF-10 lo-fer preselector
These receivers are solid state radios made with "point to point" wiring. There is little use of printed circuit boards. It is a fine receiver though. The receiver incorporates phase lock loop tuning which is extremely accurate.
Contrary to popular notion, the readout dial is NOT digital. What appears in the window is the bottom frequency of a particular 500 khz frequency segment which is printed on a drum. The band switch is marked in band segments. Each band segment has 5 - 500 khz frequency segments, the bottom of each one appearing in the window. Within each segment, you turn the "synthesizer tune" control until the bottom of the particular 500 khz frequency segment you want "locks in", the red light goes out, and the proper bottom band segment frequency appears in the window. For example, if you want to listen to SSB on 3890 khz, you would turn the band switch to the 1.5 - 4.0 position. Then rotate the "synthesizer tune" control till the number 3.5 appears in the window. The red light should go out somewhere near this point which signifies that the receiver is "locked". Then just peak the signal with the preselector knob.
When the phase lock circuit gets out of alignment, which happened quite often on the earlier serial numbered units, the red light never goes out, or the tuning never "locked". Many problems people encounter are due to poor seating of the many transistors that are in sockets rather than hard wired. Simply reseating those can cure many ills.
The familiar looking HRO main tuning knob is, however, very functional. The digits on the knob are VERY accurate and track perfectly, unlike all other HRO receivers I have had that do not.
The LF Preselector is essentially a paper weight, albeit a very valuable one. It is only used to tune in VLF stations and must incorporate the HRO-500 to function. Because so few were sold, it is more valuable than the radio istself. I do NOT have a matching speaker, though. If anyone has one they'd like to part with, please let me know.
NC-400
National NC-400
This receiver was built from 1959 thru 1963. It is 18 tubes and double conversion. The design seems to be intended as the general coverage version of the NC-303, with a sharp design departure of the front panel from that receiver but the case and case color scheme are the same. This one has the original speaker and manual. Its got several RF tuned circuits and many IF tuned circuits. It has a lot of functional opportunities including having several external oscillator crystals. Another unique feature is that the entire crystal filter unit can be unplugged and an optional mechanical filter unit plugged in. It is a very nice band cruiser.
NC-100X
Started a Revolution - National NC-100X
built in 1937 NC-100X Broadcast - 30 mhz
Requires an external "doghouse" power supply and external National Speaker
This will team with my Utah UAT-1 Transmitter
This is an early variant of the venerable NC-100. James Millen designed this to address the sometimes maligned HRO series with its many loose coils. Just as with the HRO, there is no band switching switch per se. This NC-100X utilizes a nifty flat cast aluminum compartment (called a catacomb) that glides left to right along rails under the chassis. This compartment contains a section for each band. Each section contains all of the coils and capacitors needed for each band's tuning. The big knob under the PW dial has a gear attached to its shaft which engages a linear gear attached to the catacomb. As the knob is turned, its gear moves the catacomb along the rails until the proper band is in place, as seen thru the holes on the red stripe. Pretty clever.
Hallicrafters
SX-73 / R-274/FFR
This is the Hallicrafters SX-73. The story goes that Uncle Sam gave both Hammarlund and Hallicrafters the same specifications to come up with a receiver. Hammarlund presented the SP-600 and Hallicrafters' offering was the SX-73. The SP-600 was chosen as the primary vendor and there are 1000's out in the market today. Hallicrafters DID make some of the SX-73's but their production was a shadow compared to Hammarlund. This specimen is in a nice pine wood cabinet. The speaker is the R-42 bass reflex speaker.
