The box with the two grey knobs on the left is the Herring Aid 5, the receiver that took me 38 years to complete. The box on the right is a VFO I originally built for my first BITX40Module — it started out around 4 Mhz but I pulled turns off the coil until it was in the 40M CW band. The Altoids in near center has the buffers — a 40673 MOSFET and a 2n3904 BJT. The box in the back holds the Tuna Tin 2. There the oscillator has been reconfigured as an amp. A relay switches the output from the buffers between the receiver and the transmitter. That big switch in the center switches the antenna and the 12 V for T/R. The circular black thing is piezo buzzer used for CW sidetone — I have it glued to the board upside down to keep the volume down.
The whole thing is mounted on a kitchen cutting board. A breadboard!
The most difficult part of all this was getting the needed 800 Hz drop in TX freq on transmit. You need to do this with a rig like this or else you won’t be in the other fellow’s passband. I did a lot of cut and try — in the end I put a 5 pf cap across the coupling cap from VFO to buffer. This 5 pf cap switches in on transmit via a small relay. It works. I just spoke to N8AFT out in Columbus, Ohio and I was in his passband.
So five transistors in the receiver, two in the transmitter and three in the VFO/Buffer. So it is the Fish Soup 10.
It puts out about half a watt. On CW. I am feeling virtuous and vaguely superior. I’ve made several more contacts. It all works very well and is a lot of fun.
I would love to hear more about the need for the frequency shift on transmit – never encountered that before.
Royski: Peter VK3YE explains it very well here: https://www.youtube.com/watch?v=pdaEj9DGXCw 73 Bill N2CQR
Your 40673 based SDR front-end popped up in Mike’s video from yesterday: https://www.youtube.com/watch?v=ZWEgjIG2yf4
Love it! Operating rigs of that sort is as close as we get to having a direct physical connection to the magnetosphere. Ride that ether, my friend. Ride it like you stole it!
Thanks Bill, that was a great explanation
Nice working you yesterday. Super impressed with this setup. W1ND