[R-390] DEAD BANDS PROBLEM

[Barry Hauser]

Hi John:

Could be Y406, the 12.5 mHz crystal which is used for both the 5 and 22 mc
bands.  30 mc must be something else as that crystal (Y403, 11 Mhz) is
shared by 3 other bands, 2 mc, 8 mc and 19mc.  Did you check those bands
also?  The crystal scheme is shown in schematic form on page 3-12 of the Y2K
manual (page 50 in acrobat sequence).  I seem to remember a chart that
showed the crystal usage, but forgot where that is.

Sometimes there's some corrosion on the xtal pins and all that's needed is
some deoxit.  I've also found some crystal decks with loose socket contacts.
These can be tightened up with a small blade screwdriver by removing the
xtal and pressing down on the flat contact stamping a bit.  This applies to
the simple contact type that's basically a dimple in the metal with hole in
the middle and one or two slits.

I have also found some R-390A's with bad crystals.  Another possibility --
the trimmers on the xtal deck have some corrosion.

Hope this helps.
Barry


>
> Just brought home a nice R-390A. Its a hot radio on all but 3 bands which
> seem dead - theres noise, but no signals, and no calibrator beat. The
bands
> are 5Mc and 22mc. 30mc  seems weak, otherwise a hot radio. Any ideas
> on what to look for before "working" on the radio would be much
appreciated.
>
>
> --- StripMime Report -- processed MIME parts ---
> text/html (html body -- converted)
> The reason this message is shown is because the post was in HTML
> or had an attachment. Attachments are not allowed.
> Please post in Plain-Text only.---
> _______________________________________________
> R-390 mailing list
> R-390@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/r-390
>