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Re: Ruining $4 Attenuators



Note that DEM has the SSBT "Safety Switch Bias Tee" which simultaneously
protects, and feeds power to, your downconverter, for $65. US.

And <w4tas@gte.net> made available a design for a bias tee with diodes
and a fuse for protecting the down-converter.

I'm hoping to use the DEM unit as both a safety device and a switch to
a 2M antenna for older birds, but it'll be worth it as just protection.

73, doug

   From: "hasan schiers" <schiers@netins.net>
   Date: Tue, 6 Aug 2002 13:06:34 -0500

   The first thing your 2m rig should see is something like the RF power
   protector sold by SSB electronics. It's pricey, but has saved both my step
   attenuator and UEK-3000 twice so far.

   FT-847 > Protector > MFJ Step Attenuator > 80' LMR-400 > UEK 3000 d/c


   hasan schiers, N0AN

   schiers@netins.net
   or use amsat.org or arrl.net remailer
   ----- Original Message -----
   From: <BobsImsai8800@aol.com>
   To: <amsat-bb@AMSAT.Org>
   Sent: Tuesday, August 06, 2002 11:38 AM
   Subject: [amsat-bb] Ruining $4 Attenuators


   > From K5GNA:
   >
   > Putting a Radio Shack 6 dB attenuator (model 15-1257, $3.95) in line with
   > your converted MMDS type of downconverter will reduce the no signal noise
   to
   > a more reasonable level.  Although there has been some debate on this BB
   on
   > reducing excess gain and noise in the RX, Dick Knadle, K2RIW, and others
   have
   > presented papers on the benefits of eliminating this excess gain, so the
   no
   > signal noise is reduced.
   >
   > However, the main benefit of the attenuator is for you to sacrifice a $4
   unit
   > instead of a downconverter (or another expensive device) when you key your
   2
   > meter TX into the downcovnerter. You will probably key up accidentally no
   > matter how careful you are, as I have heard many stories and even done it
   > myself.  Because of the berivety of most of the accidental transmissions,
   it
   > may not burn something up every time, but it does happen. Even the step
   > attenuators can be ruined and they usually cost a lot more than $4.  The
   > first thing that your 2 meter transceiver should see is the $4 attenuator
   or
   > somthing else cheap that will can be sacrificed.
   >
   > Bob Seydler
   > K5GNA
   > ----
   > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
   > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


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