[R-390] Crystal resurrection

[Glenn Little]

At what frequency does the repaired crystal oscillate.
I would suspect is lower than intended because of the additional mass 
added to the crystal.
The original crystal was probably sealed in an inert atmosphere.

I hope that you now have a fully functional crystal.

73
Glenn
WB4UIV



At 01:32 PM 3/19/2014, Mark Richards wrote:
>As I work through some issues with my R-390A crystal oscillator, two 
>crystals were identified as non-functioning: Y402, 10.5MHz and Y413, 
>9.5MHz.  Considering the cost of replacing these at the only 
>supplier I could find, Fair Radio, I figured that a repair try which 
>saves me $14 each is worth the gamble.
>
>After some digging, I found a fellow traveler:
>
>     http://home.earthlink.net/~chestnutl/Helptipspage3.html
>
>The author found in one instance the internal crystal structure was 
>touching the cover which prevented oscillation and, in another 
>crystal, that re-soldering was needed.
>
>Rather than use a torch, I set my soldering iron to around 800 
>degrees F and after a minute or so managed to carefully wiggle up the cover.
>
>In both crystals there was no obvious alignment problem, so I set 
>about to renew the soldering.  But, before that, I cleaned each 
>crystal using isopropyl alcohol applied carefully with a cotton 
>ball.  Then, with the soldering iron, touched up each lead, first at 
>the very base where it attaches to the pin, and then carefully moved 
>up to the crystal element, adding a bit of solder.  This was done at 
>around 650 Degrees F.
>
>Tacking the cover back to allow for re-insertion we have success: 
>each crystal came to life!
>
>Perhaps this is non-preservation-quality, but 30 minutes of careful 
>effort just saved me $28 I didn't have to throw.
>
>This R-390A radio is one tough unit!
>
>/K1MGY
>
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