[AMRadio] Progress report on my DX-100

Peter Wittenberg SR k2lrc at k2lrc.com
Tue Mar 11 20:55:18 EST 2008

Bob, you should use Simple Green 50/50 water to do the cleaning. It just runs off.
-73- Peter K2LRC
From: amradio-bounces at mailman.qth.net [amradio-bounces at mailman.qth.net] On Behalf Of Bob Bruno - K2KI [k2ki at starc.org]
Sent: Tuesday, March 11, 2008 6:52 PM
To: amradio at mailman.qth.net
Subject: [AMRadio] Progress report on my DX-100

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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