For those who couldn't find the N4TRB RCA Ham Tips for the Band Pass Coupler
If you have a transmitter you have to have a receiver. Early on the old wife's tale has it that the ARRL openly said Transmitters are easy, but you best buy your Receiver. Like most of these urban legends that may be subject to dispute.
No matter, as a receiver is needed and that certainly can be one of the Internet SDR receiving sites or you can build one using COTS, (Commercial Of The Shelf) assemblies.
Mostly DIY RF . Com has the COTS assemblies and can be found on Todd's (K7TFC) website. An earlier posting on this blog detailed those assemblies but now you get to see the COTS pieces fitted together in a prototype receiver.
Actually, you are being slightly misled by the "receiver" photo below because of the addition of one more piece already installed on the main board (Mic Amp) it is a complete low level SSB Transceiver. All the receiver assemblies + the mic amp give you that capability. You need to add three additional COTS assemblies (Driver, Final and W3NQN LPF) and you have a complete SSB Transceiver. Such a bonus... almost as good as having twin sisters as girlfriends and both are happy with the arrangement but do complain that the back seat of the 57 VW Beetle is a bit tight.
COTS Prototype Receiver
Let's tour our wooden board. In the upper left-hand corner is the Universal Digital LO/BFO and below that is the audio amp stage that I had. But I actually have the COTS audio amp and will install that unit. At the lower left-hand corner is a 4X16 LCD and alongside that is a small control panel housing the USB/LSB select, step tuning rate, main encoder and the headphone audio output.
The main board has the Mic Amp, ADE-1 for the Balanced Modulator/Product Detector, the IF Module which uses two BFR106's and a 4.9152MHz Crystal Filter, the second ADE-1 which is the RxTx Mixer stage and the 7 MHz Band Pass Filter. As was done in the P3ST we have relay steering. Oh, I added 500 Ohm gain pots in the emitters of the BFR106's. This enables me to fine tune the IF Module overall gain capability.
The last board in the upper right-hand corner is a diode steered bidirectional amp stage using two devices like the MAR 6 SM+ MMIC amp.
All of the devices mentioned are COTS from K7TFC.
Below is a shot of the prototype front panel. Often, we see the 16X2 LCD's but the 16X4 can be implemented by changing one line of code stating that you are using four lines and not two. While I added my stock message to the screen, these two added lines could give you an S Meter or capability to Monitor other functions.
The digital LO/BFO from Todd uses the Seed Xiao RO2040 and while it is limited in I/O as compared to a Nano, it has a lot more capability and is much faster. By using three of the remaining IO, I am envisioning using these pins to TR and key the Retro Transmitter.
Regrettably I am not even preaching to the choir here as I doubt anyone other an over-the-top avid homebrewer would build something like this receiver. I present this only to show the COTS assemblies are a catalog item and you don't have to send off to "Chine" to get them. The hardware is available but thanks to that organization in Connecticut the necessary skill set to pull it off has been neutered.
A couple of noteworthy items: The signals seem to pop out of nowhere and not a lot of background annoying hiss. The encoder (49 cents) sucks. I am trying to find a low PRR optical encoder which will smooth out the tuning that can be had without resorting to a home loan.
Them that know can make things go!
73's
Pete N6QW