The Peashooter: "It Is Alive!"
Update March 5, 2022, ~ Happy Birthday to the US Navy Seabees
To all currently serving and former "Seabees" Happy 80th Birthday! It is with great pride that I can call myself a former Seabee! Can Do!
The Peashooter "Rocks" as I have been working DX with my new machine including the famous station from Barcelona, Lou, EA3JE. Then again, everyone works Lou. Also reports from Argentina and Chile. This is a DX Contest Weekend --time to rack up more contacts (maybe even QRP).
The Peashooter has Soul and Presence which were all purpose designed into the rig. The MMIC's have proven their worth as circuit modules.
I have a bag of Dual Gate MOSFETS --how about a new variant called the Pipsqueak using 3N209's. Even more astonishing these 3N209's were sent to me by Wes, W7ZOI.
Update March 4, 2022, ~ Trouble Shooting and the Unexpected!
There is that insatiable urge to make lots of contacts with the new rig but after just a couple it is always good plan to really explore what you have built to assure yourself that everything is 100%. Thus, that was SOP with the Peashooter.
I noted that passing my hands near the steerable amplifier and BPF that there were some strange noises coming out of the speaker! The undeniable sounds of oscillation. This is like your 14-year-old daughter coming home from school and announcing "Dad, I think I got pregnant". Panic is an understatement!
So, then I retraced my build process, a good reason to take lots of progress photos. In the very 1st iteration, I had the steerable amplifier milled out next to the BPF. That you can see below. A voice kept saying this might not be a good idea as the close quarters are ripe for feedback. But the idea of small size won out and I felt if this was an issue, I had a way to fix this.
In a short while, as found out, it was a problem when I built the transmitter section. The fix was to build the steerable amp on a small circuit board that would use a vertical mounting. That was built and installed. For Good Measure, I added some 50 Ohm swamping resistors across some of the circuit modules. Wes Hayward is SSDRA called these band aid fixes. All seemed happy.
That is until something changed, and I am not sure what it was, but I think the issue was that the small circuit board was a piece of double side boarded where I soldered both sides of the vertical board to ground.
The idea was that one side of the board was a shield to the BPF and the other side had the MMIC circuit. It was difficult to solder that board in place because of the other already installed hardware.
Following a reasoned trouble shooting process I had the Peashooter connected to a dummy load and a snoop loop installed on the LPF. This loop connected to my DSO where I spotted some "fuzz" on the signal with just the MIC keyed. Not good!
While connected to the DSO I grabbed the Vertical Board, and I could see the simple act of wiggling the board cleaned things up quite a bit but not totally. There was a grounding issue! My solder joint on the vertical board was not a good connection to ground!
So, I took a piece of RG-174U and peeled off the jacket and pulled out the inner wire and now had a chunk of braid. I soldered that to both sides of vertical board the other end to the main top board.
The other part of the solution was how I connected to the In and Out pads of the Steerable amp. I drilled two small holes through the two-sided copper PC Board. I was careful to ream out the hole on the back side of the board. Well, what I didn't think about is the MMIC is a 3 GHz device and that wire passing through the hole was like capacitive coupling the in to the out. I then coupled to the top pads. The original back coupling was to mate up with the steering relays. The photo below shows the Braid installed and the two wires (one orange) to the In and Out pads
and thus the problem was solved. The "Grounding Gremlins" and the In/Out Feedback loop were in play.
Here is a video of the output sampled with a Snoop Loop.
***
The 1st QSO was QRP with the "5" Station who has a penchant for telling you your radio sounds best to him when you make his adjustments.
I couldn't resist calling him and he came right back to me. The 1st thing he asked me what is your radio and microphone? I was jumping for joy when I said you can't help me -- pause. Then I went on to say that I was running a homebrew QRP radio about 3 watts. He then said you are 5X8 in New Mexico. This is followed by -- your signal is 2.5 kHz wide and has a lot of highs. But it sure is punchy!
He must have been terribly disappointed that he could not tell me how to make my radio sound like he wanted it to be heard. Oh, he did state he was an expert at this as he has been doing it for six years. I have been playing the electric guitar for 20 years and can't tell you a C Chord from a G Chord. But I can make a lot of noise and so does the "5" Call.
Today I finished wiring the Final Amp Stage and fixed a few issues. One of the SMD transistors went toes up and so had to replace that jewel with a through hole.
The 2nd contact was running the external amp at 100 watts with a station in Texas.
We are awaiting some aluminum plate to complete the front panel. But the Peashooter is on the air.
The next rig will explore an optical interface and use the module steering approach. This is exciting!
Read Up on SOA's (Semiconductor Optical Amplifiers). We may be modulating Light Beams. Stay tuned --you heard it here 1st!
73's
Pete N6QW