[Heathkit] DX-60 Problem

[Gary Pewitt]

Harry, I wouldn't be surprised if there were wiring errors.  One sure way 
to fix it would be to get a manual and strip it down to a bare chassis 
before rebuilding it.  Check each component before wiring it in  and 
replace anything out of spec.  Works every time and it's fun.
73  Gary



At 10:56 AM 3/11/2006, Harry Vaught wrote:

>I bought a DX-60 at a local antique mall a couple of weeks ago.  I paid 
>too much, but it was nearly mint, cosmetically, and I had gotten a really 
>nice HQ-170C at the same booth last year.  I should have known...
>
>Both bandswitch wafers were broken and the shaft was frozen at the panel 
>bushing.  I got the shaft freed, epoxied the wafers and powered up. There 
>were fireworks from the 6DE7.  I replaced it with a 6EW7, since AES was 
>out of 6DE7's.  Since then I've rewired and recapped the power supply and 
>replaced a charcoaled R13, the 8.2 ohm resistor in the 6146 cathode circuit.
>
>The voltages on the modulator tube are a mess.  I get 500-600 volts on pin 
>6, the first section plate and on pin 2, the second section grid. Same on 
>pin 9, the second section cathode.  I've isolated the modulator tube by 
>disconnecting incoming and outgoing connections.  Nothing makes any 
>difference except disconnecting the high voltage, or removing the 
>tube.  I'm lucky I haven't cooked the new tube.
>
>Screen voltage on the 6146 is ok for CW, but high for AM.  Key-down bias 
>on the driver is about -24 volts instead of -85.
>
>The documentation has no resistance chart, only voltages.  I've checked 
>voltages and connections through the various switches 'til I'm exhausted, 
>but I'm no good at deducing problems from voltages alone.
>
>Does any DX-60 guru out there have any suggestions as to where I should 
>look?  If I don't fix it pretty soon, someone's going to get a nice 
>looking bargain.  I don't like things that don't work and I can't fix.
>
>Harry Vaught, KT4AE
>Maryville, Tennessee
>
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Gary Pewitt  N9ZSV   n9zsv at cei.net  479 675 4376
1500 French Prairie Rd. Booneville, Arkansas  72927
Sturgeon's Law "Ninety percent of everything is crap"