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Try using the 29 to get input tune right. Most of the 955’s I’ve seen on a scope and a spectrum analyzer are ugly.

You got something weird going on. It’s not this complicated. I’ve never had a problem like this. Why is the black wire going out past resistors? What is that ceramic cap right by trimmer? It should tune easily. Why is that alligator clip on there? I’ve helped all I can. Without having it...

You may wanna do about 5-6 turns on a 3/8” form. Then just use the piece of unshielded coax and start about the 4th turn and solder to. See what you get. May or may not need to move trimmer to other end of coil.

Just out of curiosity, did you try tuning input with no capacitor across input transformers? Worth a shot!

I’ve found both Motorola volumes on eBay Year’s ago. The Norm Dye book is very good as well. Worth mentioning, Radio Handbook by Bill Orr 22nd and 23rd editions have some good transistor info as well.

With trimmers across input transformers, I adjust for lowest vswr on input. Then I remove and measure. Sometimes when I pull they aren’t the same. So I add the 2 values and then divide by 2. Then whatever that number is, I try to use closest or exact value and solder the fixed value across both...

Anymore testing? Should be around 230-240pf for input tune. But with it being biased, may affect input tune slightly. Back in my early days, I put a 4610 trimmer across input transformers and tuned it properly. No guessing on values. Did this across output transformers as well. Tuned the amp for...

A 464 or 465 trimmer would be perfect for input.

It sounds like amp is more stable now. Not going into oscillation or full conduction?

Input should need 240pf roughly. On the HG2879, it needs a 470pf or 500pf across input transformers. HG have different perimeters than Toshibas. They are not drop in replacements.

I was wondering if you had gotten any further on project. Have you tested it yet?

I’ve have good luck using 1N4007 diode. I have used a file and file down 1 side of diode just to give it a little more area that touches heatsink. Tracks temperature a little better. I then use a small piece of strap or brass and solder across/ over diode to clamp down onto surface.

Good to see you on here Bob. Been awhile. Yeah the 723 design would be great. But I have a bunch of boards made up using the 7808 and transistor design. Solder together and go. For me anyways.

443, your bias circuit after looking is very close to what I use. I suggest that 7805 regulator has some kinda of dropping/ current limit going to. If in mobile or on a power supply at roughly 14v. That’s 9v roughly the regulator has to drop. So yes, it better be heat sinked. I have opted to...

It’s been awhile, there is a decent bias design in Motorola Application Notes. Just don’t remember which one at moment. Bob85 and I discussed it somewhat years ago. If I get time in next few days. I’ll have to look it up.

I like using the old RMC stuff. Also, instead of trying to find a 170pf which is extremely hard. Try paralleling 2 x 82pf or 3x 56pf which are common values.

I have always found it better to independently bias each two pill section. Then depending on circuit, you can thermal track each 2 pill/ transistor section independent of each other. Also just a heads up, bias voltage is a lot different on Toshiba transistors versus the new HG. Setting the HG at...

Ok, just asking on the matched set. I don’t know if rf parts tests or if from HG testing. I know of 1 guy that bought 100 to truly match 32 for his box. I’ve had regular HG going into oscillation by what I think was power supply issue. Had to upgrade power supply and problem went away. Issue in...

Are all 4 Rfp transistors matched?

One of those little caps are a 104 / 0.1uF cap. The ones I have are yellowish orange. I bet the green is a 1000pf. Using different values to filter out any RF. They are not inductors