[amsat-bb] (no subject)

Edward R Cole kl7uw at acsalaska.net
Tue Aug 2 17:42:06 UTC 2016


I would guess most use RF sense switched mast-head preamps since they 
are using radios with a single antenna connector.  But some folks 
modify the radio so the Rx has an independent antenna input isolated 
from the Tx so they can run a separate coax line to a simple preamp 
and use a coax relay on the antenna side of the preamp.  This 
requires a separate coax run to the Tx output.

This second approach is not uncommon approach for those involved in 
serious weak-signal VHF+ operating (which includes eme).  I have both 
approaches at my station.  I have several DEMI transverters that 
provide separate Tx and Rx antenna connection so a simple remote 
located preamp with TR relay can be used.

But I also have a FT-736R (unmodified) which can use a yagi with Rf 
sense-switched preamp and only requires one coax run.  I do have 
external switching control line to that preamp which will require 
adding ext. PTT from the FT-736R.  I originally used preamps for 144 
& 432 with separate TR relays for my AO-40 era satellite set up and 
will be restoring that this summer.  This will require modifying my FT-736R.

I use a station control panel with integrated sequencer, but that was 
done for eme and other weak-signal operation (not specifically for 
satellite).  My satellite control ckts will utilize the sequencer 
(which provides extra protection to the preamps - but not normally 
used by satellite stations.

73, Ed - KL7UW

From: Fred Castello <fredcastello at gmail.com>
To: "amsat-bb at amsat.org" <amsat-bb at amsat.org>
Subject: [amsat-bb] RF Sensing Preamps, Sequencer, or both?
Message-ID: <579fe396.e928c80a.c54fd.4af3 at mx.google.com>
Content-Type: text/plain; charset="utf-8"

Hi folks,

I am in the process of trying to set up a station here and have been 
researching equipment.  While I suspect there will be a fair amount 
of variety, I am curious to the responses to my question:

Do you use the relatively less expensive ?indoor? NON RF switching 
preamps in an enclosure near the antennas (on the tower)  with RF 
relays and with a sequencer in the shack (do the preamps holdup up on 
the tower even if protected?)  OR

Do you use RF sensing preamps mounted at the tower  OR

Both (for those that are extra careful)?  I suspect operators that do 
other VHF/UHF low signal work tend toward sequencers (one for 2 
meters and one for 440), i.e. moon bounce, meteor scatter, etc.

Also, I am curious what type/brand/model of RF relays folks use?

As usual, I really appreciate your time.
Fred Castello, KF4FC

73, Ed - KL7UW
     "Kits made by KL7UW"
Dubus Mag business:
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