[Elecraft] [K3] RX-settings w/ preamp?

[Edward R Cole]

Message: 21
Date: Tue, 01 Jun 2010 12:41:29 +0000
From: "Lance Collister, W7GJ" <w7gj at q.com>
Subject: Re: [Elecraft] [K3] RX-settings w/ preamp?
To: DM4iM <hamradio at vr-web.de>
Cc: elecraft <elecraft at mailman.qth.net>
Message-ID: <BLU0-SMTP57B2093CA643484B79326B89EF0 at phx.gbl>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 6/1/2010 11:07 AM, DM4iM wrote:
 > Elecrafters,
 > i have a masthead preamp for 6m with 18db gain wich i will install
 > today. I would like to query the VHF people ...
...snip...
 > I feel the right answer is PRE OFF in combination with ATT ON
 > for maximum performance, but i'm not sure.
 >
 > Martin

Hallo Martin,

Others may have other suggestions, but I I usually run it with BOTH 
and external and
the internal preamp on.  However, here at my location, almost 
everything I am trying
to work on 6m is very weak.  When the band opens up and signals 
become strong on Es,
I have to completely turn off the NB, and then I also can turn off 
the internal
preamp.  I have not needed to use the attenuator, but I suspect your 
strong signal
environment over there is a bit more challenging.

As far as the tower mounted preamplifier is concerned, most of the 
weak signal 6m
operators I know opt instead for low loss feedline and put the 
preamplifier in the
shack next to the radio.  A receive-only preamplifier arrangement is much less
expensive (and flexible, since you can easily add an amplifier) and 
the money saved
can be put toward low loss coax, which will help also on transmit.

GL on the Magic Band!  VY 73, Lance
-----------------------------------------------------------------
Lance and Martin,

I have my 6m preamp directly connected to the RX ANT/IN and /OUT 
connectors and powered from the 12vdc out Jack on the lower left side 
on the back of the K3.  To activate the 6m preamp (per page 39), you 
tap RX ANT button.  I see a S3 noise level when I do this and another 
S-unit of noise if I also turn on the internal preamp.  I chose to 
get the ARR P50VDG GasFet preamp with 0.5 dB NF and approx. 24 dB 
gain.  This preamp may overdrive the K3 if strong 6m signals are 
received so in that case I would use either the internal preamp or 
the ARR, but not both.

But most of my 6m operation is weak-signals and using both is 
indicated.  I currently have a 3-element yagi at 55-feet with a 
80-foot run of LMR-400 coax (~0.5 dB loss).

There was an opening from Alaska to PNW (BC/WA/ID) on Sunday evening 
(0340-0400utc) where I needed 100w of my FT-847 to make contacts as 
the 8w of my K3/10 was not enough.  The K3/10 did receive very 
nicely.  I will eventually add a linear amp to the K3/10 for 6m.

73, Ed - KL7UW
http://www.kl7uw.com/6m.htm