[K3] RX-settings w/ preamp?

[Martin-2]

Elecrafters,
i have a masthead preamp for 6m with 18db gain wich i will install
today. I would like to query the VHF people : What settings do you use
with an external preamp in line?

ATT ON or OFF?
PRE ON or OFF?

I feel the right answer is PRE OFF in combination with ATT ON
for maximum performance, but i'm not sure.

Martin

--

73, DM4iM
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[Martin-2]

I should have added that the cable used is H100, about 30m long
and has an attenuation of 2.8 db per 100m on 50Mhz.

--

73, DM4iM
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[W7GJ, Lance]

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 : What settings do you use
> with an external preamp in line?
>
> ATT ON or OFF?
> PRE ON or OFF?
>
> 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 Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: [phone]
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the MAGIC BAND EME email reflector!
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[Edward R Cole]

Message: 21
Date: Tue, 01 Jun 2010 12:41:29 +0000
From: "Lance Collister, W7GJ" <[hidden email]>
Subject: Re: [Elecraft] [K3] RX-settings w/ preamp?
To: DM4iM <[hidden email]>
Cc: elecraft <[hidden email]>
Message-ID: <[hidden email]>
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


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[W7GJ, Lance]

Hello Ed,

GL and I hope to work you on 6m soon! Both KL7NO and KL7/KB7Q were in here quite
nicely on SSB the other night :-)  Sorry I missed you!

I don't know how many K3 owners are in your situation, but the Es season sure would
be a good time to add another 10 or 20 dB on 6m!  I have a little 300w solid state
amp (6M300PA built by Down East Microwave), that might be of interest.  I had been
hanging onto it as a spare, but I do also have an 800w Harris TV XMTR that I could
use as a spare.  Both amps run on 48 VDC.

I have not pushed the 6M300PA because there may be no good way to get replacement
transistors for it anymore, but with 46 VDC on it and a little less than 2 watts
drive, I got 200w output.  3 watts drive took it up to 300w output.  A person sure
would want to be sure they didn't overdrive it or have any power spikes on XMIT, but
a low power K3 should really work FB with it.

I would consider parting with it for $400.  I can provide a power supply for another
$25.  Shipping would be extra. GL and VY 73, Lance



On 6/1/2010 7:56 PM, Edward R Cole wrote:

>
> 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
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

--
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: [phone]
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the MAGIC BAND EME email reflector!
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[Martin-2]

Elecrafters,
thanks for all the input.
So far, the preamp does a good job, now stations are readable i
don't even hear with the preamp off.

Cu on the Magic Band.


--

73, DM4iM
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