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Re: Reception improvements for Oscar Echo



Patrick,

Very good!  You apparently understood that your reception suffered from
cable loss between the antenna and first stage of amplification.  Although,
your reception would benefit from a low-noise preamp, you have optimized
everything else to get the best performance (only direct connection to the
antenna would improve it more).

I wonder if grounding the antenna actually has much effect (on its
pattern).  You might try disconnecting the ground and observing how much
difference it really makes.  I suspect the feedline improvements are what
is really helping, most.  But grounding may quiet the antenna from static
noise pickup in certain wx.

The answer to your question on a RF switched preamp is that it will pass
whatever Tx RF that is sent (most likely).  RF detection is usually not
freq dependent.  But you would not be able to receive during transmission
(not operate full duplex).  It is better to have full duplex for satellite
operation so that you can confirm hearing your own signal (and avoid
transmitting over another station).

The only solution to using a common feedline would be the use of diplexers
to bypass the preamp.  Not very cost effective.

Not knowing the FT-8800, I assume it has a single antenna connector and
uses an internal diplexer for full duplex, or it doesn't operate cross-band
duplex.  In the latter case the RF-sensed (switched) preamp could be used
to improve your reception with no impact on operation (be sure to mount it
directly to the antenna for maximum benefit).

73's Ed - AL7EB 

At 05:57 AM 2/22/2005 -0500, McGrane wrote:
>Greetings; de N2OEQ Patrick, LI NY
>
>I made some changes in my station setup that improved reception of Echo
>without a preamp:
>
>Moved diamond 500 Vertical closer to shack, replaced 50 foot of 9914 with
>21 feet of 9913. Antenna is mounted on 12 foot aluminum mast. Attached
>short ground wire from bottom of mast to 8 foot ground rod. These two
>steps resulted in sequential improvements in reception.
>
>I also removed watt/swr meter from circuit and ran coax direct to ft-8800
>dual band rig. Meter was rated .2DB loss at 430 MHz. Tried weak signal
>test with friend about 10 miles away running 300 MW into unity gain
>vertical. With meter in line, he was in the noise and not readable. With
>meter out of line he was readable.
>
>These steps were taken over the last few days while Echo was transmitting
>at 2 watts. Reception was greatly improved. I heard CU2LX below 3 degrees
>elevation and several stations below 10 degrees elevation which was new.
>
>I'm trying to do what I can to avoid spending 230 dollars for a mast
>mounted preamp. Another question: Can one transmit VHF through an RF
>sensing UHF preamp? 
>
>As stubborn as I may be, I am trying to prove that someone with a standard
>home station can work the satellite.
>
>Hope this helps.  73, patrick N2OEQ 32323
>----
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