[Elecraft] DC-supply for a preamp?

[Edward Cole]

Martin,

I installed an ARR P50VDG preamp on the back side of my K3/10 using 
preamp in/out connectors on the KVX3.
photo: http://www.kl7uw.com/K3-ARR-6mPreamp.jpg

I will control the power via the ACC jack when I get a VGA jack.  For 
now it is on when the K3 is on.
Much easier and safer than using a bias tee  and remote switched 
preamp.  I agree with Lance that you will not likely see any 
improvement in sensitivity mounting the preamp at the antenna.  For 
keeping loss down use LMR-400 coax for runs up to 100-feet, and 
LDF4-50A Heliax for longer runs.  This keeps transmission losses down, too.

73, Ed - KL7UW
I run 80-feet of LMR-400 to my 3-element 6m yagi at 55-feet on the tower.
http://www.kl7uw.com/6m.htm

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Message: 2
Date: Tue, 27 Apr 2010 16:25:52 +0000
From: Lance Collister <w7gj at q.com>
Subject: Re: [Elecraft] DC-supply for a preamp?
To: DM4iM <hamradio at vr-web.de>, Reflector Elecraft
         <Elecraft at mailman.qth.net>
Message-ID: <BLU0-SMTP74DD81C59BD56FE6E1BA3989030 at phx.gbl>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 4/27/2010 2:32 PM, DM4iM wrote:
 > Elecrafters,
 > this might be a rig-killer and vy stupid, but....
 >
 > Can i power a 6m masthead-preamp by feeding dc via choke and coupling
 > C's to the KXV3A's in/out sockets (where the elecraft preamp is supposed
 > to sit), or is this a big NONO?
 >
 > Martin
 >
Hello Martin,

I think you could do better by simply installing the PR6 at the K3 
and using low
loss coax to the antenna.  Almost all the 6m EME stations around the 
world use a
good external preamp in the shack.  If your coax cable loss is 1 dB 
or less, you
will not gain anything by mounting the 6m preamp at the antenna.

You can model this for yourself in the EME CALCULATOR (accessed from 
the EME ECHO
MODE screen in the old WSJT Version 4). Because the EME CALCULATOR 
and EME ECHO
MODE were never re-written in the language used in more recent 
revisions of WSTJ,
that old version is still available:

http://www.physics.princeton.edu/pulsar/K1JT/WSJT498.EXE

I think you will find it much simpler to keep the preamp in the 
shack!  GL and VY
73, Lance

-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, 
ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728   URL: http://www.bigskyspaces.com/w7gj
LIVE MESSENGER CHAT: w7gj at hotmail.com
2m DXCC #11, 6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the Magic Band EME email!
http://6meme.com/mailman/listinfo/magic_6meme.com


73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
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