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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 25th Nov 2020, 8:37 am   #1
LA9CHA Thorvald
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Default Contact disks for HP8640B.

Looking for information of where to order spare plastic disks for HP8640B signal generator. The contact disks are for the FM-Range unit and are the circular disks with small contact lips, all parts of the gear assembly.
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Old 25th Nov 2020, 10:19 am   #2
LA9CHA Thorvald
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Default Re: contact disks for HP8640B

Actually, the contacts are perhaps called contact nipples!
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Old 25th Nov 2020, 6:32 pm   #3
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Default Re: Contact disks for HP8640B.

This is the later version of the 'A9' range/deviation assembly and you will find many posts on it within this Forum. I have not found a supplier for replacement discs other than picking up 'donor' 8640B's (also known as 'spares mules').
The main problem with these is loss of the spring-loaded contact wipers due to the plastic carrier becoming brittle with age / heat ... and sometimes the small white plastic 'pips' that are positioned opposite each contact set and which provide a counterbalancing force to keep the disc parallel to the A9 printed circuit board.

Forgive me if you knew this already.

Best wishes
Guy
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Old 25th Nov 2020, 7:54 pm   #4
LA9CHA Thorvald
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Default Re: Contact disks for HP8640B.

Many thanks Gui, I tried to make two wipers from a discarded switch, and I was lucky and managed to glue them to the disk and it now function fine!!
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Old 25th Nov 2020, 8:51 pm   #5
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Default Re: Contact disks for HP8640B.

Is it the clear plastic disk? If so then there is one on ebay, not sure if it's OK to post a link as it's an auction listing.

David
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Old 25th Nov 2020, 11:14 pm   #6
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Default Re: Contact disks for HP8640B.

The second part of Rule C3 says that you may post an eBay link in response to a request for spares. As this is a wanted post for that part you can post the link.

You must not discuss the seller or the listing.

Cheers

Mike T
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Old 26th Nov 2020, 8:53 am   #7
Jon_G4MDC
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Default Re: Contact disks for HP8640B.

PLease can someone post dimensions of these contacts?

Are they similar in size to 8558/9 Spectrum Analyser. I note they are a pair of split fingers rather than 4 wider fingers.
Material is 5 thou thick for 8558/9.
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Old 26th Nov 2020, 12:18 pm   #8
factory
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Default Re: Contact disks for HP8640B.

Quote:
Originally Posted by Cobaltblue View Post
The second part of Rule C3 says that you may post an eBay link in response to a request for spares. As this is a wanted post for that part you can post the link.

You must not discuss the seller or the listing.

Cheers

Mike T
Thanks for confirming it's OK to add a link for the wanted post.

Here is the auction for one of the clear contact rotors, I bought one a while ago just in case, they may have more.
https://www.ebay.co.uk/itm/184545564987

David
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Old 28th Nov 2020, 7:10 am   #9
LA9CHA Thorvald
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Default Re: Contact disks for HP8640B.

Hello David, I made a bid and WON the disk! Many many thanks! Merry X-Mas!
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