[AMRadio] Progress report on my DX-100

Bob Bruno - K2KI k2ki at starc.org
Tue Mar 11 20:52:10 EST 2008

Hi all,

I just thought I would share what I have been doing to the DX-100 
transmitter that I got the other day.

The whole radio looks like it was dipped in a nicotine vat and left to sit.

First, I removed the chassis from the enclosure which BTW does not have 
any holes drilled in it but it too was brown and sticky.

I noticed right off that the 6AU6 VFO tube was cracked and was white 
inside. I then tested all of the tubes and found the 5763 Driver tube 
had an open filament. The 12BY7 Xtal Oscillator tube was also bad. My 
tube tester (B&K Dynajet 606) does not test 1625's. I have 21 NOS and 5 
used but working 1625's so I can replace both without breaking a sweat 

I then inspected the topside of the chassis. There are numerous places 
where the chassis is rusted. It looks like something dripped down into 
the rig. Other than that, a good cleaning will make it shiny-new. The 
Final tank will need some attention but not too much.

I then inspected the underside of the beast. It looks just like the day 
it come out of the box. All shiny and new. There are a few bad solder 
connections and the caps need to be replaced. The .1 MFD 600V cap has a 
crack running from one end to the other. The Power Xfrmr was clipped out 
of the circuit and reconnected. I would say that it probably died and 
was replaced with a Xfrmr from a donor.

Other than the above, all looks extremely promising.

Now to the fun part... The front panel...

I first removed all of the knobs and felt sick just holding them. All of 
them were caked with hardened hand oils and nicotine. I couldn't even 
scrape them clean. So, I soaked them for about 3 hours in a hot soapy 
water mixture with some vinegar mixed in. After I scrubbed them with a 
toothbrush, they came absolutely clean. Oops. I think I used the XYL's 
toothbrush. Shh don't tell her :-)

While the knobs were soaking, I had at the front panel. The paper towel 
that I used for the first pass was brown and stank. It took me 3 hours 
to completely clean and degunk the panel.

After reinstalling the knobs, I stepped back and realized that I 
actually made progress. Seeing that thing turn from a brown box-shaped 
turdlet to a shiny vintage xmitter, made me feel better about the whole 

Next installment will be the chassis cleaning and capacitor replacement.

I took pics along the way. I posted them on my Photo Bucket acct. Here 
is the link:


Until next time...
73, cul...
Bob de k2ki

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