[Drake] Re-cap on TR-4

[Garey Barrell]

Mel -

Most likely a short on the filament line somewhere.  Look at the 
schematic (verify it matches your serial number) and examine the series 
/ parallel filament wiring that includes the dial lamps.  It's possible 
that it is a heater-cathode short in a tube, shorting the filament 
string to ground at that point.  Bottom line is something is shorting 
out a portion of the string, increasing the voltage on the rest in that 
string.  Measuring the filament voltage across each tube "may" help.

1.  Any electrolytic is suspect.  Lacking an ESR meter, just replace 
them.   Watch polarity!

2.  The can is not for shielding, underchassis caps are fine.

3.  It's a start!  :-)

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://hr99.home.mindspring.com/R-4C_Servicez/>



Mel Vance wrote:

>Have a TR-4 with an intermittent problem, both TX/RX but worse on TX...lights will suddenly 
>get very bright, audio goes to pot, and jumps freq...a good tap or two and rig returns to 
>normal function....
>
>I suspect bad caps or tube (all tubes except driver and finals test good...driver and finals are 
>all very weak)
>
>1) do new electrolytics need to be in the cans for shielding, or is it ok to remove the leads 
>and solder new caps under the chassis? Can get the correct values locally, but are too large 
>to fit in the cans....
>
>2) are there other caps that have a known common trend to go bad?
>
>3) am I on the right track, or do I need to look elsewhere for the problem?
>
>Am looking to get the rig up to a better value for sale/ swap for solid state rig, 160-10 
>including WARC and 60...something with extended RX that can be mod for full TX like a 
>440, 735, ect. Has other issues that I may or may not be able to deal with (1 segment of 10 
>does not work (dirty contact? bad xtal?) and missing a knob)....
>
>Mel
>N7OKL
>
>
>  
>