SG-85 URM-25D HF signal generator Military 1-60MHz test teardown

vintage military HF signal generator 115V ONLY, transformator only got that one mains winding ! unit seems to be working, the only thing i found missing was 400-1000Hz modulation osc, but it works fine with external modulation AM only.
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#military
#vintage
#teardown
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I use auto generated subs, I go thru them my self, but i am far from perfect at finding all errors, so if you find errors worth fixing, please comment (or PM) with the TIME in the video you saw the error, i will be happy to fix it. This also apply to the Danish version.
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(Thanks to all my Sponsors / Traders / Swappers / Sellers / Buyers, without your support and constant flow of cool items in/out, none of this would be possible)

[@IMSAIGuy]

Had one once. Thanks for opening it up. I sold mine and never got a look inside.

[@elext9q]

The Dallas Lankford guide pdf (available online) was an absolute necessity for teardown/restoration, extremely helpful.

[@barryschwartz567]

This generator dates to the early 1960's. You have the D version. There are versions from A to F. Note that the large adaptor on the cover is used with the crystal calibrator. It allows headphones (phone jack) to connect to the XTAL CAL output (BNC). You listen for the zero beat tone on the headphones. To calibrate the output level, set the MICROVOLTS control to maximum and adjust the SET LEVEL control for a reading of 10 on the meter. Then you adjust for the desired level with the MICROVOLTS control. The attenuator setting shows how much to multiply the meter reading to get the output level in microvolts. You have correctly noted that the output level varies considerably with frequency so that the calibration adjustment needs to be done whenever the frequency is changed. You set the modulation control correctly so the modulation oscillator is probably not working. The specified frequency accuracy of the generator is 0.5%. If you use the crystal calibrator, the accuracy improves to 0.25%.

[@elext9q]

Thanks for the info!

[@TheGmr140]

Wow, that's a beast

[@redneckways1933]

I have this but it came with no top so i do not have any of the goodies. If you need parts it is here. All tubes seem fine when i booted it up.

[@elext9q]

Mine came with the lid but with all accesories missing. I might have to build my own attenuators etc