The W1IA Web Page
(click on pics to enlarge - high-resolution - dial-ups beware)
Link Coupled "Tina-Tuner"
The secondary is made up of 36 turns of 3/8's inch soft drawn copper wrapped on a 4 1/2 piece of pvc. The center of the secondary is grounded and brought back to the SO239 bulkhead. The link is made using two pieces of 1/4 inch thick lexan (4 3/4 by 4 3/4 inch squares). By cutting a 1/4 inch slot half way through each piece and sliding them together you form an X coil form. I drilled 14 holes on both sides of the lexan about 1/4 inch from the edge. I wound 14 turns of #8 solid on a 3 1/2 inch piece of pvc and wound it onto the coil from and slid it into the center of the secondary. The difficult part was soldering the #10 teflon jacketed wire on to each loop of the center link. The teflon wires were brought out to a piece of lexan mounted on a double studded insulator in order to provide a tap-able link. The link is tapped with teflon wire and alligator clips and brought to a SO239 bulk head. The cap is a Jennings 385pf 10kv and mounted in parallel with the secondary.
Under Construction 375 Watt 160 Meter Class-E Deck
Pre-Paint
Finished 160 Meter Deck Pre-Paint
Deck Class-E Pattern H-Modulator
The heat sink was out of a Micor commercial repeater and was milled clean and flat for a smooth platform for mounting the mosfets. The power mosfets are Fairchild FQA11N90's. The gates of the mosfets require approx 24 volts p.e.p. and drive is 10 watts provided by my FT-990 and feeds the input coil (shown on upper right side of chassis). The FT-990 provides frequency control with an un-modulated carrier. The coil is a center tapped inductor (44 turns total) one side going to ground. This matches the 50 ohms to the lower impedance of the gates and feeds a pair of amidon torroid cores (type 43 material) on the RF deck. The cores are wrapped with a 6:1 ratio to further match the input impedance and are out of phase with each other to drive each 5 fet module. The gate and drain leads of the fets are connected using 3/4 inch brass strips The double sided copper board provides a solder-able ground plane for the source leads. Each 5 fet module require 2000 pf of shunt capacitance (2 -1000pf ceramic doorknob caps). All fets are mounted on Sil-Pads for d.c. isolation and heat-sinking. The output of the modules are connected out of phase to the tank circuit through 2 transformers made up of 6 Amidon 43-1020 cores and are a 1:1 ratio. The 46 volts modulated dc from the class-h modulator is applied to the drain buss of each module and is bypassed with .15 pf 400 volt mylar caps. The inductor for the tank is tapped approx 16 uh made up of an edge wound silver plated coil. The series tuning cap is a Jennings 10kv 385pf vacuum variable padded with a 500pf doorknob cap for as total of about 900pf. The loading cap is a receiver type that is tied to ground and padded with 2000pf of doorknob cap for a total of approx 3000 pf. T/R switching is done with an open frame relay and provides connection for the ft-990 and redirect for receive to gate drive in transmit. Shown next to the deck is a picture of a perfect class-E wave pattern on the scope.
The New 375 Watt Class-H Modulator
Finished Pre-Paint Pictures
The modulator will run 375 watts carrier and easily 1500 watts P.E.P. Included in this design is negative peak limiting, over current protection, HI/LO tune, band switching for 160, 80 and 40 meters. The class-H modulator board is a prototype from WA1QIX and will be available in a few months. The power-supply is made up of a transformer from "Toroid Corp. of Maryland" and produces 62 and 124 volts D.C. after full-wave rectification and two 59,000 uf 75 volt caps (center tapped for the 62 volts D.C.); required for the two banks (5 per bank) of IRFP260N modulator fets. A step-start circuit reduces in-rush current to protect the full-wave bridge. The over-current protection circuit samples the modulator current through a .1 ohm 25 watt resistor to ground. The over-current relay is wired in series with the sequencer ptt and provides lock-out in case of a fault. The sequencer by W2DRZ is used to simplify the keying circuits. The sequencer allows 4 stages of keying: 1) RCVR mute 2) driver 3) antenna relay 4) B+ to modulator. The Class-H design modulator provides a modulated 46 volts D.C. to a 10 FET Class-E RF deck. All power to generate RF comes from the modulator. Frequency of operation and gate drive for the Class-E RF deck is supplied by any solid state transceiver or synthesized driver. Typically 30-35 watts is required to drive the gates of the Fairchild FQA11N90 mosfets on the RF deck.
The Finished Rigs in Service
 |
 |
 |
 |
 |
 |
A complete treatise on Class-E designs by WA1QIX - http://www.classeradio.com/
The Class-E Forum - A home for Solid state builders by N1GTU - http://classe.monkeypuppet.com/
E-MAIL --w1ia@comcast.net--
remove dashes for e-mailing (spam harvesting)