I’ve been back at gluing the me squares for the signals strength meter and two tone tester, components have arrived so I can get on with building them once I’m ready.
My sudden SSB TRx is long overdue some work and I’ve finally make a little progress, I’m missing a few components but got the remainder of the toroids wound and installed and added the capacitors for the crystal filter. Once the other components have arrived I’ll finish this off, I’ve also ordered the components for the s-meter driver and two-tone tester so I can make a start on them.
I’ve built the first section of the three part transmit amplifiers board, I need to test it using my VFO/BFO and scope or RF probe, but I haven’t quite got round to that yet, it seems that I didn’t quite complete the VFO/BFO, it’s missing a couple of bits and pieces including the rotary encoder!
I’ve got the microphone amplifier built although not tested yet, I need to decide what mic I’m using and attach it up to test properly, if it’s an electret mic there’s an additional resistor required to provide the required DC supply. Very little else to tell really until I test it, just happy to have another module built.
The LPF really goes together with the PA, in the GQRP Scratch QRP documents it suggests building and testing them together, however I hadn’t worked out which capacitors I was going to use so I built and tested the PA and then the relays before coming back to this. In the end I used some silver mica capacitors which I purchased from Hifi Collective, they are a little pricey compared to normal capacitors, however they had the values I required so no doubling up etc required and they more than meet the requirements.
No huge issues with this build apart from removing the enamel from the wire for the inductors, burning off with the soldering iron is my preferred method, however I still struggle to get it burnt off enough and clean enough to easily solder. My connections seem decent but I feel like either I’m doing something wrong or there must be a better way, yet scraping off with a knife or using sandpaper seems slow and a bit ’iffy’.
I’ve got moving a bit again on the sudden transceiver project, after completing the PA earlier in the week I’ve got the relay switch board sorted and tested, this switches both the antenna (relay on the left) and 12V supply (relay on the right) between the RX and TX chains and sets the D4 pin on the Arduino high to tell the VFO/BFO module when we are transmitting.
So five months on from preparing the board I’ve FINALLY got round to completing the PA, I had a couple of hiccups but no huge dramas, other than a short circuit which lead to some smoking wires!
First of all despite getting the voltages where I expected I wasn’t getting any current flow, with the help of one of the club members, Dave G8KBB, we discovered that I had a dodgy solder joint, one of the wires I was using too connect a couple of MeSquares wasn’t soldered down air one end, we then discovered that I didn’t have the threshold voltage right, once we discovered that it started working very nicely.
I’ve attached the IRF510 to a heatsink to keep my mounting options open, but most likely I’ll get a metal case and bolt it to that, if not I’ll keep the heatsink, detach the solder tag, bend the middle leg up and attach via a piece of wire.
While I’m off the air I thought I’d start preparing the PCB for the next portion of the sudden transceiver which I’m (very slowly) building, the power amplifier. I’ve not really been working on this project just due to lack of spare time at the moment as I’m focusing on CW operation while the bands are good, I know that during the winter I’ll struggle with my evenings on 20 and 40 meters, although I might try to put together an 80m compromise antenna in the loft or across the garden for the winter.
So I finally got round to uploading the sketch to the Arduino and successfully loaded up the VFO/BFO. The sketch uploaded without any issues, it was a simple process and it all works correctly, just needs properly calibrating at some point.
A little more progress on the VFO/BFO, I’ve completed the “build” and now need to upload the sketch to the Arduino, I’m just awaiting a USB C to Mini USB cable to connect it to my laptop. Once I’ve got the cable I’ll be able to setup the software and test the VFO/BFO.