[Boatanchors] B&W TR Switch 381C

[David C. Hallam]

So how does this affect weak signal reception?  I haven't used a TR 
switch since my novice days when I home brewed one out the handbook.  I 
don't remember the noise floor being a problem, but then maybe I 
wouldn't have known the difference.

David
KW4DH

On 8/14/2014 1:06 PM, manualman at juno.com wrote:
> It's normal. The tube used in the TR switch acts as an RF amplifier to
> the receiver. When RF is applied, it just cuts the tube off protecting
> the receiver input. With the Johnson TR switches, the noise floor between
> roughly 3 to 22 MHz is raised a number of DB's. Below 3 MHz and above 25
> or 26 MHz, at least with my Johnson TR switches, they start to act like
> attenuators.
>
> Pete, wa2cwa
>
> On Thu, 14 Aug 2014 11:37:06 -0400 "David C. Hallam"
> <dhallam at knology.net> writes:
>> I have a B&W 381C TR switch that has been sitting on the shelf after
>> I
>> purchased it at a ham fest several years ago.  I tried it out for
>> the
>> first time today on 20M with my 73S-3 receiver.  The noise level at
>> my
>> QTH was running about S-3.  When I put the TR switch in the line and
>>
>> peaked its tuning, the noise was about S-7 or 8.  Is this normal or
>> does
>> it indicate a problem with the TR switch?
>>
>> David
>> KW4DH
>

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Thomas Jefferson


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