Technical information

Front View
I would then download the user and alignment manuals and all the N4PL files plus the 3 flavors of
sprocket repair. The annotated schematics are excellent. Use these in combination with the User
Manual module schematics.
After all this fun, I strongly suggest not attempting to work on this rig unless you have RF circuit lab tech
experience and a pretty robust set of lab equipment with a calibrated VTVM like and HP-410C and a
quality frequency counter. Replacement parts are all pretty “unobtanium” except for NTE replacement
matches, caps and resistors. Buying a parts rig is also highly recommended.
Suggested First Steps
1. Power up for 48 hours with a variac or 100 watt light bulb in series with the AC mains to re-from
old electrolytic capacitors. I have not had to replace any high or low voltage capacitors after this,
fingers crossed.
2. Verify/adjust all AVR board voltages. I adjusted 8.2VDC and 5VDC no problem but my 6VDC
output for was a low 5.3VDC (should be 5.5-6.5VDC and is used solely for VFO. After
considerable research, I discovered that the 2SC372Y transistors are very poor fab/materials
and the 6 volt regulation was horrible resulting in a 50Hz transmit-receive delta. I replaced Q658
with an NTE85 and I now have 6.2VDC with very good regulation. I subsequently changed all
other 2SC372Ys on the AVR board hoping to improve 8.2VDC regulation. This second effort
yielded marginally better improvements.