Electronics > Metrology

Gertsch Ratio Transformer - maintenance

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Rax:
I just acquired a Gertsch PT-5 in good cosmetic shape. It seems very precise - just about on par with my RV722 DC divider (within the bounds of the expected accuracy of AC vs. DC of my meters, but frankly it is a bit surprising how exact it is).

The switches, though, are a bit fussy. This must have sat for decades. What have others done with this in terms of maintenance? Just work the switches to get them mechanically clean, or open it up and condition with some Deoxit? Unsure what would be advisable, though can't imagine the second option harming anything.

Thanks!

Vgkid:
Have you read this yet:
http://www.ciphersbyritter.com/RADELECT/RATIOTRN/RATIOINS.HTM

Conrad Hoffman:
I'd use a small amount of Deoxit, using a toothpick or something, rather than spraying it everywhere. That should do it. FWIW, most of those ratio transformers are more accurate than similar resistive dividers. General Radio was able to specify them within 200 ppb!

Rax:
I used a cotton swab moist with Deoxit (but excess wicked away), and then I placed the rotor contact "leaf" in between positions (so I'd have access to it) and wiped it. Mind you, the top and bottom deck don't have the rotor contact in the corresponding place - so I had to switch to different positions top vs. bottom to gain access to the rotor contacting leaf.

It seems all good now to me.

Thanks both!

guenthert:
Google finds: http://manuals.repeater-builder.com/te-files/MISCELLANEOUS/GERTSCH%20RadioTran%20Instruction.pdf

If I understand the nomenclature correctly Gertsch PT-5 is the Gertsch Products RatioTran model 5, listed in their catalog as RT-5.  Or perhaps the renaming of the models happened when Gertsch became part of Singer?

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