[Milsurplus] Re: Plastics turning to cheesecake

[Bob Camp]

Hi

A number of plastics get used in equipment. The band switch drive train 
on the 8640 looks a lot like nylon to me. Of course I am no expert. 
Nylon is interesting stuff. It dries out and shrinks over time. I have 
always assumed you could fix the problem by simply boiling the 
offending parts for a while.

	Take Care

		Bob Camp
		KB8TQ


On Apr 17, 2005, at 9:17 PM, Al Parker wrote:

> Hi guys,
>     Hue, maybe you, living out there in the great NW (I think), know
> something abt this, but I heard it today & was a bit alarmed.  
> slightly on
> the same topic--
>     I told a friend, at the Raleigh, NC, 'fest today, that I was kinda
> looking for an HP 8640 sig. gen.  He told me that he'd had a few (he 
> has a
> small commercial repair shop) but was steering away from them based on
> info from knowledgeable sources, and reports he had on failures, that 
> the
> plastic used for the bandswitching mechanism (a turret?) was reaching 
> the
> end of it's expected life and they've been failing.  Strictly a 
> mechanical
> problem, and difficult, if not impossible, to remedy.
>     Anybody have more input on this?  BTW, he said the 8654's don't 
> have
> the problem.  I'm not familiar with the construction of either.
> 73,
> Al, W8UT
> New Bern, NC
> BoatAnchors appreciated here
> http://www.thecompendium.net/radio/
> http://www.hammarlund.info
>
>
> Message: 5
> Date: Sat, 16 Apr 2005 20:13:20 +1000
> From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
> Subject: [Milsurplus] Re: [The WS No.19 Group] Plastics turning to
> cheesecake
> To: <Wireless-Set-No19 at yahoogroups.com>, <milsurplus at mailman.qth.net>,
> "Hue Miller" <kargo_cult at msn.com>
> Message-ID: <011001c5426c$eb299800$0404a8c0 at brian>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Could be de-polymerisation of the poly-vinyl-chloride. Well-known 
> problem
> with house wiring = great income earner for electricians.
> Brian.
>   You wondered:
>   I wonder: what is going on here. Is the "plasticizer" which lends
> flexibility or some softness to plastics based materials, now 
> migrating to
> the surface? Or?
>   Will all plastics based components meet this fate - the still solid 
> ones
> just waiting their turn?
>
>
>
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