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*** I just had an interesting thought. I bet I could do an RF speech processor in software. I have a few Teensy 4.0 processor sticks - they have a very powerful audio library - with oscillators,

One of mine had a leaky driver transistor that caused all sorts of weird stuff. CAREFULLY check the voltage on the base of the drivers. It should be zero in RX. I would not measure directly at the

Selectivity of the R-4C crystal filters is better than the R-4B’s 50 kHz L/C filters. Sensitivity very similar, maybe slightly better for the C-Line. Rob, NC0B

Sometime during the production of the TR7 the 470K in series with pin 4 was added to provide the high level input. The three rigs I have all have it. It was also added by the service department to

Have been working on the TR7 CW issue and today I changed the switching transistor that turns on the 10 volts and off. Before I changed the PNP transistor when the key is up it showed 1.77 volts and

Okay, ground strap added, not much difference, but makes really good sense! Anode on CR1501 RX = close to 0Volt, TX = 11.5Volt Junction CR1502/CR1503 RX = 10.32Volt, TX = Unstable - constant cycle

this is what I’ve been using master-carr 9541k8 listed as thread stud bumper 6-32 thread size 1’4” long Mike, WB8VGE SunLight Energy Systems The Heathkit Shop http://www.theheathkitshop.com/ J e

If you go this route, be sure that you’re buying the shorter ones. There are some that are too tall to fit in the PA cage. Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana. Sent

And it’s not as important to have exactly matched tubes but it is important that they all be the same brand. Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana. Sent from [Proton

6GJ5 tubes have been used as a less expensive alternative. ?Do a search and you’ll find some info and can decide if you want to try them.

Dave, a quick review of eBay shows several 6JB6/6JU6 going for around $15 NIB + shipping. Perhaps you can find someone with 3 for sale. Dave

Yes, I failed to mention that. BIAS is at 0.1 amp. So, sounds like everyone agrees, it's the finals. That is an easy fix! But rather expensive. Where are folks finding the best deal on new finals? 73,

Mike is right about the AC-4 small rubber feet with the stud at 6-32. Steve is right about the 10-24 screw for the large plastic feet. PS [email protected]> wrote:

Yup - 10-24 Common Slot Pan Head IF you want originality. I can get the length for you later today. 1/2" or 5/8" sounds about right. 73 PS [email protected]> wrote:

If you have confirmed that your idle current is 100mA then I would agree that your finals are tired.

Ok, my readings compensating T9 de-tuning on 10m. All relatives, of course. 10m 30V 400mA 105W 15m 27V 420mA 135W 20m 28V 390mA 165W See that with more or less the same "p-p drive level" I got higher

They are not new, but they test OK, about mid-way on the output scale. Is it not a valid way to test final tubes? 73, Dave

Steve and the group those small rubber feet that screw into the bottom of the AC4 are in fact 6-32 thread. You can get the rubber feet from McMaster Carr, although I don’t remember the part number

I believe the latest manual, available at WB4HFN, shows the pinout for the two mic inputs.

These are not new finals, correct? This appears to be finals that are at their end of life. Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana.