The AM Forum

Acquired an Eico 720 in the Spring for $25: replaced the PS caps, the 6CL6 Osc tube, and 6146 final it was working FB on all bands.  After trying to get a homebrew PP 807 modulator to work with it (I need to do a little on the modulator) I put it away in storage until now.  Tried resurrecting it yesterday and it has several problems:
- Bandswitch is so stiff that it can barely be turned: any suggestions on how to loosen it up?  I can't remember if it was this stiff or not when I but it away in storage
- I get full 3 ma grid current (both in Tune/Transmit modes) on 20M with a 14.286 mhz crystal; but oddly with out pressing the key I get 0.5 ma grid current on both 80M (with a 3.885 crystal) and on 40M (with a 7.290 crystal), and when I press the key the meter deflects down to 0 ma.  Drive or Drive Tuning does nothing to move the meter
- I get no plate current on any band in either Tune or Transmit no matter what I do

I haven't had a chance to do voltage measurements as my digital VOM gave it up last week; and my RCA WV77e VTVM is apart waiting for a new battery.

Any suggestions on where to start?

73  Alex

Put the WV77e back together. I don't think you need the battery to do voltage measurements.

Spray or dab some WD-40 or equivalent at the front of the switch on the shaft where it enters the switch mechanism. Work the WD-40 in while turning the switch back and forth through its positions. Depending on the type of rotary switch, you might need to also do the same thing at the rear of the switch. Make sure the wiper contacts on each switch wafer make contact with each fixed contact position.

WD-40 worked great on the bandswitch, and I started to do voltage measurements having got the VTVM back together.  Haven't finished all the testing but definitely strange stuff going on as voltages are good on the PS, but way down on the Osc.  Hope to finish up tomorrow.


73

Alex