If the ts-520 doesn't pick up the ignition noise and the bitx-40 does then it is shielding in the radio's that are the difference. A hole cut in the front panel for an lcd is a *big* hole for ignition

#bitx40

Evan, IIRC this is how the old Collins KWM-2 used to do CW. Injection of an audio tone. Again, IIRC that's how you did the spot function on cw, turn on the audio osc and zero beat it with the received

If on CW we are truly just using a square wave for a signal then Jim is correct, the LPF for 80m is just not sufficient. The 3rd harmonic on a square wave is what, about 10db below the fundamental? So

#ubitx

Odd order harmonics are typical of a square wave. f, 3f, 5f, ..... This tells me somewhere in the amplifier chain there is a stage that is being overdriven significantly and the output of the amp is f

#ubitx

Jim, These graphs don't show much more than the earlier ones. 2nd harmonic on 80m and 3rd harmonic on 40m/20m need to be investigated. A low pass filter for each band could fix these but it would be b

#ubitx

Not a problem, Jim. When I get mine I'll do the test. For spurs you shouldn't need a two-tone generator, just a simple audio oscillator. You might want to make sure you aren't seeing some kind of weir

#ubitx

Nice job. It looks like all the bands except 20m are pretty good. I assume this was straight cw. I don't see any spurs. It would be interesting to see the same sweeps with an audio tone feeding the mi

#ubitx

Andy, I've always used 450degF with my smd stuff and have never had a problem soldering anything. I don't use a pointed tip but one with a small flat on the end, a *very* small flat. Don't remember wh

I am marked to get individual messages under Subscriptions. I show nothing from bitx20 in the spam folder at my email provider. The "No Email Deliveries" under "Last Unsuccessful Attempt" is what real

I am not getting any messages from the bitx20 group. My last message was #61157. Under "Most Recent Unsuccessful Attempt" it shows: "No email deliveries" Do I need to change something under the Subscr

IMD can be caused by two things, saturation at high power and cross-over distortion near idle conditions. I suspect the high standing current prevents cross-over distortion which is why you get better

iz, 3rd order and higher IMD can occur in *any* stage in the RF transmission path. It can actually happen in audio stages but that only affects the quality of the audio, it doesn't generate RF interfe

Back in March, 2018 I tried building up an amp section using an HP mmic I have in the junk box. It worked very well on the desktop. Flat from 3Mhz to 30Mhz. No oscillation. I simply could find no way

I don't think paralleling the filters will impact the nominal input impedance of each filter. If you have a SA and have something to generate a 45Mhz signal you could sweep the filters in parallel and

Should the pad after the balanced modulator be changed to add more loss? That should be easy to do. tim ab0wr

Allison, I agree with everything you have said here. I really don't have anything new to offer at this time. I've moved on to other, more pressing projects. Perhaps I'll get back to the ubitx as the w

Yep! That's the whole point of a single point ground! Run the negative lead from the radio to the battery! tim ab0wr

Respectfully, having fought noise problems in several different cars and trucks, dependence on the dash to provide a ground or even depending on the floor pan of the vehicle is a good way to introduce

Allison, The scope is perfectly usable when used as intended and you know what it is telling you. The known problems? I was the first to try adding an mmic after Q90 to help with making output more co

That's my whole point. It's why I say find the compression point under CW generation and don't go past it with peak SSB loads. A scope works fine for this. It's far easier and cheaper to do than with