DX-100 mod info wanted

[Brian Wood]

I've found quite a few mods for the DX-100, but I can't find one that was
apparently done to mine. One of the mods I have found indicates that the
drive pot is subject to failure. The circuit in my DX-100 has been modified
such that the 6.8K resistor in series with the pot has been changed to three
2W resistors in series with a total value of about 25K. In addition, the
other side of the pot, which was grounded, has been connected to a 4.7K/2W
resistor to ground. This was all probably to keep the control from
overheating, but I can't find it documented anywhere. One side effect seems
to be that on the bands with higher drive available (160/80/40), the pot is
cranked down all the way and I still have too much drive. I have to back off
on the driver tuning to keep the grid current below 6 mA, and thus I can't
peak it.

Does anyone know about this mod?

As an interesting side note, I tracked down the original owner of the rig.
His name and call were written in the manual. I found him on qrz.com still
living at the same address 50 years later! He's now 87, still going strong,
and it turns out that he's a former test tech at Collins Radio, who tested
the radios that went into the Apollo 11 lunar module. I had a great
conversation with him and he sent me a picture of himself at the controls of
that DX-100 taken in 1958. This was really an unexpected reward for me, as I
had no idea where the rig came from when I started down this path. Still
trying to figure out the rig's whole journey. He explained part of it: He
bought it from a local guy who had built it but who hardly used it. He
loaned it to his brother-in-law who then sold it with his permission. Some
of the correspondence between him and his brother-in-law was included with
the manual! Fascinating!

73,

Brian, W0DZ

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