Additionally, for the SSB tests what was the AF signal source? Clark Martin KK6ISP

Sorry, but you description below is akin to bad driving directions… (turn right at the green house, etc). It would be far easier and more accurate to specify where the signal was measured (and how). i

Use an RF probe or oscilloscope to trace the signal through the relays / filters. Clark Martin KK6ISP

Except that you’ll have voltage across the PA V+ and main V+. If the PA V+ is actually negative the parasitic diode in the final transistors will conduct and you’ll have reverse voltage to the main V+

Years ago I zero beat (although I didn’t call it that) an NE555 running at 60Hz to the AC line by connecting an analog voltmeter between them. As it neared zero beat the meter started swinging back an

What is the idle current into the PA with the mic PTT pressed (or the equivalent)? It should be 400 mA max. That’s measuring the power just into the PA section. The radio as a whole should be 500mA ma

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If you are in or near the US, try tuning in WWV on any of it’s frequencies. Clark Martin KK6ISP

I’m quite familiar with reactance from years of working with it. Clark Martin KK6ISP

Quite normal. The receiver input is to a mixer through a transformer. At DC the transformer shows approximately 0 ohms. And in general many RF devices will show approx. 0 ohms DC resistance for one re

Ah, you picked the good one, based on a Linear Technology chip. Many Buck-Boost converters will not operate well near unity (Vin = Vout), but this one does. I’m using one as a built in charger for a L

Power is always applied to the finals, Tx or Rx. In Tx the bias supply is activated, which, through the bias pots, biases the MOSFETs up to the idle current. If the FETs are heating in Rx it’s because

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If the output MOSFETs are heating up on power up with out being in transmit, they are toast. Clark Martin KK6ISP

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Check the supply current to the PA with a meter. If it’s significantly higher than the idle current, say 250-300 mA it’s probably damaged. To be sure, turn the bias pots to the full clockwise position

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Idle meaning PTT pressed but no modulation. Sent from an iPhone, don't ask whose.

Clark Martin KK6ISP 146°C would be the junction temperature max. According to the datasheet I’m looking at, the thermal resistance from junction to case is 83.3°C/W. Which means if it’s dissipating 1W

A little web searching shows TE is the owner of Axicom. This is very common in the industry, one company acquires another but leaves the acquired company’s name intact and prominent. Clark Martin KK6I

I live in California and Proposition 65 warnings are everywhere. They worded it so stringently that, I suspect, that many businesses put the sign up just in case. It is a totally useless law. I’m not

Don’t worry about transmit until you fix it in receive. Start tapping away, initially with a finger then a hard plastic probe. First determine if it’s on the main (RF) board or not. If it’s the main b

Make sure they aren’t shorted together. Check the encoder inputs then turn the knob a minimal amount and check them again, only one should have changed. Clark Martin KK6ISP

I’ve seen some gear where the CPU clock frequency can be changed dynamically so any birdies from the CPU can by avoided. The AVR328 internal clock can be divided down from the crystal frequency under