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0v at vr16 wiper to ground, .697v at anode of (shows d51 on my board and schematic)

I hate to ask but is it possible you have cw and ccw reversed in the image? Regardless, full clockwise is .607V, full ccw is .732V with a very linear adjustment through full travel so something is still amiss. This is with mic keyed and no audio input. Not sure if this is a clue but with the...

I've got TR43 unsoldered, awaiting a replacement. It tested fine on diode check but I know that doesn't neccesarily mean it's good. VR16 tests fine also. With TR43 out of the circuit, is there anything I can check before installing new final? Also, I only eyeballed that L30 slug. If that was far...

I drill the roof and use NMO mounts as I like Larsen antennas. The NMO27 is pretty decent at about 4 feet tall. My current setup uses a Larsen 30mhz coil with their 64 inch whip cut down to about 62 inches. Works quite well on my barefoot McKinley.

I experimented a lot with electronics as a kid after getting my first Science Fair 60 in 1 kit. Got real interested in digital stuff and started breadboarding logic gates and sound synthesizers (man I miss my SN76477s) but RF circuits made my brain hurt at the time, kinda skipped over it. Then I...

Gotcha. I was wondering if the final I installed from the other radio is actually bad. A simple diode test across the junctions showed good but I imagine there could still be an issue with it. I don't think I transferred too much heat soldering it. I'll poke around a little and probably pull...

Vr16 does change it, midway was about 150mA, all the way down was around 100mA. I'll reflow the wiper terminal. Vr16 checked good, going from wiper to unused terminal and taking it through full travel shows almost zero to 290 ohms and pretty smooth for watching on digital mm. I'll certainly...

Yes sir. Every component I've checked has been isolated even if it meant removal. I'm quick with this iron and solder sucker though. I just finished checking c172, d66/d67, c169 just because they're in the vicinity. All good. Man we're on page 3 with this thing I'm probably wearing you guys out.

Ok I rechecked my work, all looks good. Voltages look good. Driver bias still good at 40mA. I'm using a different meter as the first one was showing an unadjustable .28mA at TP2 in the milliamp range but when I switched to 10 amp range and moved the lead to the correct jack on the meter, it read...

All check good. I had my leads connected wrong at TP2 by the way, I'm only getting 0.28mA at key up. VR16 still makes no change and I did retest it. I'm done for the evening. I'll recheck my solder work and check some voltages tomorrow to make sure I didn't create a problem. Sure appreciate the...

I let the power supply run for about 20 minutes with the fuse removed and it held steady at 13.8v so that's cool. Set radio to USB, keyed mic, no audio, TP4 showed about 68mA, VR15 brought it down to 40mA no problem. TP2 however shows a little over 3mA and adjusting VR16 hardly has an effect. Hmm.

All check fine. I also found my non conductive heat sink compound and got the final installed. This rig is back together and triple checked for solder blobs. I don't have a watt meter yet, would my rf volt probe tell what needs to be told at the antenna out? I'm assuming I'll need to check bias...

Roger that. I'll lift some legs and test this evening. Good stuff.

Hah, old final drops .006v base to collector, leads either way. Yep.

Sweet. Got the donor out, drops a little over .6v at both junctions and OL with leads reversed. I need to order some heat sink paste and umm a watt meter. Be a couple of days and I'll get these bits in and see where I'm at with this classic. Thanks you guys.

Hair dryer worked like a champ, slug swapped. On to C174 and TR43. I have no idea if the final in the donor radio is good but I'm going to pull it first. Would a simple transistor junction voltage drop check using the diode function on my meter be of any value before installing?

I wonder if it would be easier to swap the whole thing. I've got a good solder sucker and temp adjustable soldering station I used for the recap. The slug in the parts radio is still sealed, never been turned.

More info. I measured rf voltage through a few points in the driver and final stages on AM into dummy load. Referring to the schematic; location 150 reads .402v dead key going up to about .480v with auuuudio. 155 reads 14.8v dk up to 22.0v with audio. 158 reads 1.12v dk up to 1.35v with audio...

Ok it's transmitting, just weak. Rx into mobile sounds good up to about 1/2 mile out then quickly drops to no copy by about a mile and a half.

So, transmitting into a dummy load, the mobile in my jeep, about twenty feet away, is able to clearly hear the 458 on AM and sideband. It's weak, but very clear. I'm wondering if I should hook my vertical up to the 458 and take the Jeep for a ride. I think my wife would humor me for a few more...