[Boatanchors] B&W TR Switch 381C

[manualman at juno.com]

If the weak signal was 2 db above the noise floor without the electronic
TR switch, it will still be roughly 2 db above the noise floor which is
now higher with the electronic TR switch inline. It just raises the
entire base line.

Pete, wa2cwa

On Thu, 14 Aug 2014 13:54:31 -0400 "David C. Hallam"
<dhallam at knology.net> writes:
> 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