[amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE

[Art McBride]

To All,
The Diplexer also acts as a filter. All solid state transmitters have "White
Noise" contributions. If you receive while transmitting the White Noise from
the 2M side will desense the 70 cm receiver. The amount of noise typically
60 dB down from the carrier varies with the type of output filter used in
the transmitter.  Of course this does not apply when working the satellite
simplex. 
A bad diplexer can also be the problem. Soldering is poor in some of these
overseas units, also excessive power in a former life will cook the parts
inside. A good test with 50 loads and a power meter will tell the condition
of the diplexer.

Art,
KC6UQH

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Joe
Sent: Friday, September 25, 2009 6:43 PM
To: Gary "Joe" Mayfield
Cc: 'AMSAT-BB'
Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE

as in the texts below,  there is something else going on here.

That Diplexor can not be all that bad. two reasons.

How many db down is the front to side of that antenna?

and I can not imaging someone would sell a diplexor that has greater 
than 20 db of losses.

because of the statement that how criticalpolarity was with the 
original, and now the antenna has to be nearly 90 degrees cross 
polarized to make it drop out  uhh

that close to 30 db,

at least 20,,

something else is going on here

Gary "Joe" Mayfield wrote:

>>
>>Another issue I came across was how wide the beamwidth is of the Arrow
>>Antenna between the Arrow diplexer and the new diplexer.  I was wondering
>>    
>>
>if
>  
>
>>this was going to happen and it did.  The reason that this happened was
>>    
>>
>with
>  
>
>>the old diplexer, the signal attenuated so much that you had to be pointed
>>right smack dab on the bird, a few degrees off and you lost the signal.
>>Now, with the new diplexer, you can point the beam in the general
>>    
>>
>direction
>  
>
>>and still copy the bird.  In most cases I had to turn the beam 90 degrees
>>before I completely lost the downlink!  Twisting the antenna to make
>>polarization changes makes absolutely no difference now.  This also
>>attributes to the fact that now I'm copying the entire pass without
>>    
>>
>dropouts
>  
>
>>or fades.  Makes sense.  What I've regained over the lossy diplexer makes
>>    
>>
>up
>  
>
>>for any polarization differences, etc. for a better copiable signal.
>>
>>Next weekend I will have to try more passes and get a feel of how much
>>    
>>
>this
>  
>
>>system has changed.
>>
>>
>>73,
>>
>>Jeff  WB3JFS
>>Las Vegas, NV
>>DM26
>>
>>
>>
>>
>>
>>
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>>    
>>
>
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