From: Garey Barrell 
Subject: Re: [drakelist] R-4 Noise Blanker


Garey Barrell  made an utterence to the drakelist gang
----------------------------------------------------------------------
This is a multi-part message in MIME format.
--------------070905090900090807080306
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Stephan -

First, have you put in a "known good" tube at V3?  The 12BE6 is one of 
the less consistent tubes even new.

The grid voltage on this stage is a function of the crystal activity, 
among other things.   Possibly the crystal itself.

I have attached a revised Noise Blanker threshold adjustment procedure 
that may address this part of your question.

Let us know what you find!

73, Garey - K4OAH
Atlanta

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



Stephan Sever wrote:

>Stephan Sever  made an utterence to the drakelist gang
>----------------------------------------------------------------------
>This is my first posting to the drake list, hope I get
>it right! I am having a problem with an R-4 receiver
>in the noise blanker. The receiver has had a full
>alignment done, and is working very well except when
>the noise blanker is turned on. Signal strength is
>reduced considerably and the incoming signals are very
>distorted, the same effect as if the blanker threshold
>was up too far. By doing some signal tracing with a
>scope it seems the NB is working but is being
>overdriven (for lack of a better term). All
>resistances check good, but upon doing a voltage check
>I had about +3V on pin 1 of V3 (12be6) instead of -11V
>as the manual called for. I found C62 
>(12 pf) was open, but after changing it the voltage is
>now at -.7V or so, not -11V. Still doesnt seem like
>enough negative bias on V3 and the noise blanker still
>isn't functioning properly. If anyone has any
>suggestions or have had this problem before I would be
>happy to hear from you. Many thanks and 73
>                           Stephan Sever II  KG9BV
>
>  
>

--------------070905090900090807080306
Content-Type: image/gif;
 name="NoiseBlankerTuning.gif"
Content-Transfer-Encoding: base64
Content-Disposition: inline;
 filename="NoiseBlankerTuning.gif"
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---