[Boatanchors] Fw: Fw: [Milsurplus] R-390A Help Needed

Mon, 10 Mar 2003 09:10:38 -0600

Signals will be low if the 9Mhz crystal (used on both 7 and 24) isn't 
oscillating up to snuff. Low levels into the mixer reduce mixer 
sensitivity. Check the E-402 point (especially relative to the others), 
the trimmer cap may not be peaked or the crystal may be weak.

How is 15Mhz ?

73  Kees K5BCQ 

--------- Forwarded message ----------
From: "Brian Jeffrey" <[email protected]>
To: <[email protected]>, <[email protected]>
Date: Mon, 10 Mar 2003 07:00:40 -0500
Subject: [Milsurplus] R-390A Help Needed
Message-ID: <001801c2e6fc$ad40d710$0601a8c0@hp1>

The original problem was the receiver being dead below 8MHz. Both V202
and 206 checked out OK so I opened the crystal oven and cleaned the
contacts on the 17 MHz xtal. The receiver came back to life but still has
one problem. The sensitivity on the 7 and 24 MHz bands is pathetic. The
sensitivity for most bands (except 7 & 24 MHz) is less than a microvolt
for 10 db s/n ratio. The 7 & 24 bands are about 30 microvolts for 10 db
s/n ratio.

I know the 7 & 24 MHz bands are tied together but I don't know why the
sensitivity is so low. Can anyone offer some insights?

Thanks.
Brian
VE3UU

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