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

The output filter relays in the uBitX are double pole double throw, one pole switches the input of the filter, the other switches the output of the filter. The original relays have too much capacitive

i thinking there might be something wrong with the IC. I’d try a different LM359. Clark Martin KK6ISP

Every time I run into resistors with ambiguous color codes I grab the DVM first thing to check them. Clark Martin KK6ISP

I should have said you need to subtract the Tx idle current instead of the Rx idle current. Sent from an iPhone, don't ask whose.

You also need to subtract the Tx idle current. You can find this by keying up the mic with no audio input. This current is mainly the bias current in the finals but also the relays and some other thin

Per the Axicom and Virtual spec sheets, the Axicom draws about 20% more power. That could mean a larger gap and thus lower contact to contact capacitance. Clark Martin KK6ISP