W7ZOI 20 Meter SSB/CW 20 Watt Transceiver
         
 
 
This is a example of a my version of W7ZOI's 20 Meter QRP Transceiver. My modifications include the addition of an internal a 20 watt RF Linear Amp, a VFO Stabilizer (EI9GQ Design) and semi-break in CW. I have worked many DX stations with this radio. The AGC is super smooth and is not subject to overload
 

W7ZOI

 
With the EI9GQ VFO Stabilizer this radio has held the frequency constant within 10 Hertz over a 24 hour period. This addition enables an analog type VFO compete with a DDS without the noise. The only short coming is that the frequency must be locked every time you QSY but I don't consider this a major Inconvenience.
 
 
 

Version #2

This version of the W7ZOI design has the following modifications: The packaged IF stage (MC1350) was replaced by J310's in a cascode circuit and is similar to the design Wes provided in his book EMRFD. The power out put stage was built using a bipolar transistor a 2SC2075 to produce about 2 watts and that in turns drives a homebrew linear amp using a pair 2SC3133's to produce 30 watts output. The small linear amp is a module that is attached to the back panel of the radio. This version has no receiver RF amp stage like in the original design. But Version 1 does which I added and I can tell that it is a worthwhile addition. Version 2 now sports a Blue background LCD display --really cool!

 

Click on the Photo

W7ZOI Construction Article

Part 1

Part 2

(Adobe Acrobat Required)

 

G4GXO 80 Meter Belthorn Special 8 Watt SSB Transceiver
 
 

Belthorn Front

 

 

Top

 

 

Rear RF Deck

 
             
 
This is my version of the G4GXO designed Belthorn Special. This transceiver uses bi-lateral circuitry so that many of the circuit elements are used on both transmit and receive. It is a single bander for 80 meters and uses a 9.0 Mhz IF. and incoprporates the EI9GQ VFO Stabilizer, A nice addition is to be able unbalance the SBL-1 DBM so that a carrier is generated for tune up. The SBL-1 used for the Product Detector and Balanced Modulator
 
The main circuit board as well as the VFO stabilizer are visible in this photo. The main board is a 4X6" piece of single sided copper board and the circuit is drawn on the board and where a ground is called for the component is soldered directly to the board. All other point to point wiring connection are made on the underside of the board.
 
The Tx and Rx Amplifier Chains are based on the W1VT circuit used with his 7.0 MHz transceiver as featured in the ARRL Book "QRP Power." The transciever delivers 8 watts out. Using the same techinque as the main board these stage are exteremely stable and the ground plane has made this a solid design
 
Note: In the conversion to 80 Meters new code had to be written so that the VFO subrtracts from the IF Frequency. Contact W6JFR for the revised code. EI9GQ's standard code only works for subtraction of the IF from the VFO frequency. It also requires a redirection so that a negative drift correction is subtracted not added since there is a subtraction already in process. This was provided by EI9GQ.