[Milsurplus] Next project - LM13 type

[WA5CAB at cs.com]

Hutch,

I don't have a 74028 here at the house to look at (although I strongly 
suspect you aren't going to like the answer).  But I strongly suggest, before 
you go and dig the triple out, that you make damn certain that's the problem.  
Disconnect the wire going to the capacitor from the tube socket and do an 
out of circuit test on the capacitor.  And as a double check, tag a new 
capacitor in place right at the socket.  If that fixes it, and the unit belonged 
to me, I would be inclined to leave the external capacitor in place.  If you 
are doing the repair for someone else, you will have to get their 
permission to do that, of course.

In a message dated 5/1/2009 10:06:38 PM Central Daylight Time, 
olegerityincj at austin.rr.com writes: 
> Good evening all again -
> 
> Setting the scene:
> Found the LM13 "in a ware house" got it at a bargain price,  has Metal 
> covered calibration book and clean inside. 
> Tested the tubes - Audio tube tested real HOT, Mixer and Master 
> Oscillator tube barely good, usable on an calibrated I-177B tube tester.
> Hooked up to Heathkit IP2717A variable power supply to the LM-13. Audio 
> output weak.  Found voltage measurements pg15 of LM-13 manual NAVER 
> 08-5Q-38
> Tube 76, cathode target voltage 6 V; cathode measures less that 1V with 
> 126 V applied to, measured at the plate pin.
> 
> Problem -
> So the stink'n three section capacitor 110(a,b,c) is located [[under the 
> tuning capacitor] in the  tuning capacitor  housing]  ...Argh ...
> 
> Please provide a solution on how to remove - C110  Help help ....
> 
> Thanks
> Hutch
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480