From: Garey Barrell 
Subject: Re: [drakelist] TR7 display


Garey Barrell  made an utterence to the drakelist gang
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Mike -

Start by sticking a piece of wire into the "CNTR" input on the back 
panel under the "NORM EXT" switch and switch to EXT.  Key an HT or some 
other source from 1-150 MHz and see if the counter counts reliably.

If it does, but is still squirrelly on NORM, check the VCO input to the 
counter on Pin 13 of the U9010 (MECL 10116) IC, second chip to the left 
from the right rear corner of the DR-7 board.  You should see ~0.4 V 
p-p.  If this is ok, then check Pin 3 of the same chip.  Should find 
~1.5V p-p on a positive DC offset. 

Results?

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
http://hr99.home.mindspring.com/R-4C_Servicez/>



Mike Williams wrote:

> After an hour or so of receive mode, the digital display starts to 
> count all over the place.  Every band and mode but the frequency is 
> stable as indicated by the same signal being present.  Looks like a 
> thermal problem of some kind. Turn the radio off for 20 seconds and 
> back on and after a few seconds the display goes wild again. I cleaned 
> the easy to access connectors but did not remove the display card.  
>  Any suggestions on this? 
>  
> Thanks for the input!
>  
> Mike W4DL

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