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SX-140 with 6M Preamp Installed?

 
Edited

Anyone seen one like this?? I bought this off eBay years ago and it's been sitting in a box until yesterday.? Took it out for a look and was surprised to find that I had two more tubes than shown in the manual or schematic.? And a large box mounted as shown in the picture with a 6AG5 tube on it's top and a cable running from the box to underneath the chassis.? There was also an extra IF looking transformer and an additional 6BA6 mounted between the new trans can and the existing one.
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I can barely make out, scratched into the top of the box, 6M Preamp and some voltages, I'm guessing are what the cable has to pick off from under the chassis.
?
Tested the tubes and brought it up on the variac and Dim Bulb.? Dial lamps light up but no audio (or smoke).? Haven't started troubleshooting yet as I got sidetracked with the
extra tubes and transformer, not to mention "The Box".? ?Any insight on this?
?
Thanks,
?
K8NN
?
 

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Common practice back in the "good of days" when we were a lot more creative. Maybe original owner didn't want the preamp "box" hanging off the back end of the receiver and he had room inside the receiver to mount it. Over the years, I've installed homebrew preamps in receivers and VHF/UHF transceivers. Sometimes when I was selling the rig at a hamfest, I even remembered to add a schematic for the addition inside the manual.
Pete, wa2cwa
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On Thu, 05 Dec 2024 13:46:07 -0800 "John Limbach, K8NN" <john@...> writes:

Anyone seen one like this?? I bought this off eBay years ago and it's been sitting in a box until yesterday.? Took it out for a look and was surprised to find that I had two more tubes than shown in the manual or schematic.? And a large box mounted as shown in the picture with a 6AG5 tube on it's top and a cable running from the box to underneath the chassis.? There was also an extra IF looking transformer and an additional 6BA6 mounted between the new trans can and the existing one.
?
I can barely make out, scratched into the top of the box, 6M Preamp and some voltages, I'm guessing are what the cable has to pick off from under the chassis.
?
Tested the tubes and brought it up on the variac and Dim Bulb.? Dial lamps light up but no audio (or smoke).? Haven't started troubleshooting yet as I got sidetracked with the
extra tubes and transformer, not to mention "The Box".? ?Any insight on this?
?
Thanks,
?
K8NN
?

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