Version II of 15 Meter / 10 Meter SSB Transceiver - Update, Finalization, DX Results

Рет қаралды 606

Күн бұрын

Пікірлер

@M0NTVHomebrewing 7 ай бұрын

Hi Bill! Thanks for watching the video of my 15:10 rig and it's great to see yours. You're absolutely right about space - I had to shoe-horn everything in to what for me is quite a small enclosure. I much prefer the large metal bread bins that have housed at least a couple of my creations or even the plain wooden board of the Shelf-17. But having set myself a challenge I was determined to rise to it. My main concern was how the modules would interact with one another and I feared for amplifiers turning into oscillators. In the end it all worked pretty well. All I need now is for conditions to improve so I can really start working some DX on 10W! Thanks again. 73, Nick M0NTV

@tcarney57 7 ай бұрын

It's cool the TIA amps can be recognized on sight, hand-built or otherwise. I think it's the trinity of 3904s that is the give-away. A few other thoughts: 1) Pete has a method for setting the bias on the final MOSFET by looking at a sample of the actual final-amp output rather than shooting for a particular gate voltage/drain current. I haven' t tried it myself, but it makes sense to look directly at the results and set the bias accordingly. 2) Regarding the need for shielding, I think much has to do with a person's particular RF/EMI environment. Apartment dwellers can't control most of the digital and impulse noise that sometimes floods in from the ever-growing number of noise sources. Also in my case, I have three 100KW FM towers glaring down on me from Portland's west hills, and I can hear one of them--KINK 102 (yes, that's its real call)--with just a little wire on the input pin of an LM386. I don't know how it's being discriminated, but I can hear it. Unrelated to that, my RX noise floor is around S5 on 20M, with gusts up to S7. It's pretty damn noisy around here. I've got to keep circuits pretty buttoned up to keep that out (and a deep FM notch filter on the antenna feedline), and to keep out the noise from the upstairs-neighbor's digitally-controlled (why?) washing machine. Anyway, in addition to definite need in my case, I'm rather fond of prophylaxis. I take a low-dose aspirin every day, and I also use a lot of that copper shielding tape. --K7TFC

@matthewmcdevitt6792 7 ай бұрын

Those are some rare, precious POLYSTYRENE caps you got there. You can only get them secondhand now. Great for ham radio projects but not necessarily to replace electrolytics ;) The different capacitor types each have different specifications, different pros/cons, that's why they make them out of different materials. I'm really not shocked your polystyrene caps didn't make good electrolytics.

@4youian 7 ай бұрын

Nice build Bill. I noticed there are a couple of those Kemet caps laying on the audio amp and the crystal filter. Watch out for those! 73, Ian, VK7IAN

@soldersmoke 7 ай бұрын

Ian: Do you have any info on what the problem might be with the Kemet caps? 73 Bill

@soldersmoke 7 ай бұрын

Oh man, I found them! Good catch Ian. They must have fallen out of the box! 73 Bill

@4youian 7 ай бұрын

@@soldersmoke Hi Bill, I can only guess that they might have high leakage allowing DC to get into the mixer. Just a guess.

@MirlitronOne 6 ай бұрын

Glad I'm not the only one who spotted that! It bothered me all the way through!

@technishn 7 ай бұрын

Those capacitors may be a axial Tantalum (either wet or dry) Sounds like leakage. Try measuring with a series resistor such as 10 -100k. Apply a suitable DC voltage across both. Measure DC across the resistor with applied voltage and you should measure nothing, after a short period of time. (perhaps 1 minute) If there is substantial leakage, it may be a bad batch.