[Drake] R4 Problem?

[Bob Macklin]

It looks like it is a dirty band switch. I'll put it back on the bench this 
afternoon and clean it.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"

----- Original Message ----- 
From: "Garey Barrell" <k4oah at mindspring.com>
To: "Drake" <drake at mailman.qth.net>
Sent: Thursday, September 23, 2010 10:16 AM
Subject: Re: [Drake] R4 Problem?


> Bob -
>
> It sounds like your BAND oscillator, PreMixer or PTO have quit.
>
> Can you actually TUNE signals when the Preselector peaks?
>
> If not, what happens if any one of the above stages quits is that you
> are peaking the Preselector on the 5.645 MHz IF frequency.
>
> It may be as simple as dirty bandswitch contacts on the BAND oscillator
> crystal selector wafer.  Possibly just exercising the switch, or a bit
> of DeoxiT, will clear it.
>
> The setup is the PTO  at 5.455 MHz is mixed with the BAND oscillator at
> 18.1 MHz for (40M) in the PreMixer.  The difference frequency (12.645
> MHz) is selected and applied to the First Mixer where it is combined
> with the 7.000 MHz incoming signal to produce the 5.645 MHz IF signal.
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 2-C/2-NT, 4-B, C-Line&
> TR-4/C Service Supplement CDs
> <www.k4oah.com>
>
>
> Bob Macklin wrote:
>> I have not been listening to the bands for several weeks. Last night I 
>> tried to use my R4A to listen to a group on 7190.
>>
>> I could not hear any activity so I tried tweaking the preselector. I was 
>> set for 40M. But I found the maximum background noise from the 
>> preselector when it was tuned to the 80M region.Then set up for 80M. I 
>> found the maximum noise from the preselector when I set it to the 40M 
>> region.
>>
>> This morning I put the receiver on the bench with the signal generator. I 
>> can find the 80M and 40M signals just fine where they should be but the 
>> noise peaking of the preselector is not where I expected it.
>>
>> The preselector does peak a signal jut like it should. I am just 
>> wondering why I get the maximum background noise at a different position 
>> of the preselector.
>>
>> I live in a RF HOLE!
>>
>> Bob Macklin
>> K5MYJ
>> Seattle, Wa.
>> "Real Radios Glow In The Dark"
>>
>>
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