[R-390] Re: [R390] R390A trimmers

[David C. Hallam]

Graham,

Can you translate paxolin to US English?

I am having a devil of a time with trimmers in a 75A4 and have about decided
I am going to have to take them apart.  A job I dread.

David
KC2JD/4

> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of Graham Baxter
> Sent: Thursday, August 16, 2007 4:06 AM
> To: r-390 at mailman.qth.net
> Subject: [R-390] Re: [R390] R390A trimmers
>
>
> I did manage to get all the trimmers working again. The problem was
> that the lower ceramic disk was no longer anchored by the rubber to
> the paxolin. I dismantled the trimmers and washed them in alcohol. I
> also polished the silvering where the spring contact will press. I was
> then able to reassemble them using a spot of cyanoacrylate adhesive
> either side of the rubber. This has worked well. One of the trimmers
> had a broken ceramic disk. I reassembled this with cyanoacrylate glue.
> I bridged the crack on the silvered part by soldering a piece of
> copper foil across it. I would have liked to use conductive silver
> paint but I didn't have any. This trimmer at least is scheduled for
> replacement when I have spares.
>
> I found my 9MHz crystal was poor. I tried a cheap HC47 wired crystal,
> just poking the wires in the holder, and it worked fine on 7, 15 and
> 24 MHz. So I opened the old crystal, removed the blank and replaced it
> with the entire new crystal. I replaced the can and it looks great.
> Interestingly there was a tiny fracture at the edge of the old blank.
>
> R390A s are not so common in the UK. I am fortunate to have a couple
> of friends who are enthusiasts. As well as two EACs I also have a
> Racal 1772.  It is good but not as good as an on-song R390A.
>
>
> Thanks for your interest
>
> Graham
> G8OAD
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