[amsat-bb] Re: Polarity Switcher Relay - repost

[Bob Stewart]

--- Bruce Robertson <broberts at mta.ca> wrote:
> Bob:
> 
> An important factor you don't mention is the coax to your antennas. If you
> are not using preamps, the losses of the cables decrease the noise figure
> of your reception by the same ratio, and this can add up very quickly to an
> unworkable situation. 

Hi Bruce,

Sorry, about that.  I'm using wireman's #106 which is a low-loss foam
RG-8 type with both braid and foil shielding.  Also, there's only about
35 feet of it, so the loss should be be very low.

> I think most of us also believe from experience that mast-mounted, low
> noise preamps (from ARR or SSB USA) do far more for a station than polarity
> switching. These are not inexpensive additions, but, especially  on 70cm,
> they are indispensable. 

Here's what's happening.  From about 20 degrees up to about 30 or so, 
reception is iffy.  After that, I sometimes have full quieting and sometimes 
nothing.  I suppose I need to do a real study of it on one satellite, but 
it just seems that it should be a polarization issue.  I do have a spare
coax going up there, so I guess I could just make a LHCP version to 
be sure.  Getting it out on the roof means that I have to make a much
more robust version.  I was hoping to put that off until I was completely
sure that I've got a configuration that works properly.  It's much easier
for me to just move the antennas to the back yard when mowing season
is over  (I'm disabled).  Fortunately, I have a semi-finished attic with easy 
access.

Another thing I've been thinking of is that once I'm comfortable with
messing around with relays etc on 70cm I might be able to use a DEM
preamp with my own switcher.  Thus my question on the relay.

Bob - AE6RV