Re: Another 7D20 attenuator question


Hi Dallas,
Tek began making their own parts out of necessity in the late 1960s. Some parts such as timing capacitors had to have exceptional characteristics for the instruments they went into to meet specifications and to hold calibration over long periods of time and environmental conditions. Timing capacitors that were part of sweep circuits are a good example of a component Tek made themselves. Tek also had to make the ICs that the on-screen readout of the 7000 series used. Later they were making their own high frequency analog ICs.
I do not know what it was about other manufacturer's relays that Tek did not like but at one point they decided to make their own relays. The "relay expert" they put in charge wasn't an expert after all. The Tek made relays that went into the 7000 series instruments have been a huge problem ever since.
I have removed lots of them from plugins I reduced to parts. I must have had about 100 of them in several configurations. I manually tested a few of them before giving up on that strategy because it took so long. Instead I built a little test fixture to test them and went through them all much faster. I must have tossed about half of them as not working or not reliable.
If you send me the part numbers of the ones you need I'll see if I have any of them.
Send it to me off list at dennis at ridesoft dot com.
Dennis Tillman W7pF

-----Original Message-----
From: [] On Behalf Of Dallas Smith
Sent: Tuesday, July 07, 2020 10:33 AM
Subject: [TekScopes] Another 7D20 attenuator question

My second 7D20 attenuators started acting up. Cleaned relays and substrate to no avail. I noticed that the 'A12 & A13 substrate PCB has tarnished relay contacts. there are a dull gray (lead?). I thought Tek gold plated PCB contacts for non corrosion and good contact resistance? Is there a way to gold plate the contact areas. Were they ever gold? I think this is the root problem with these plugins, cleaning seems to have no effect. Reluctant to buy another unit with this factory design error.

What do you say?

Dennis Tillman W7pF
TekScopes Moderator

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