[Elecraft] Subject: Re: Is it just me?

[Edward R Cole]

Seems there are two threads dealing with the same topic (also: Re: 
[Elecraft] Advanced Receiver Research P50VDG 6M Preamp):

I have both the PR6-10 (installed at the K3) and a ARR P50VDG 
installed at tower-top of my main 6m antenna.  I run 70-foot of 
7/8-inch Heliax to the box with the ARR preamp and coax TR 
relay.  The ARR preamp feeds a run of RG-213 back to the bypass input 
connector of the PR6-10.

So I can compare directly the ARR or the PR6-10.  The ARR has more 
gain and slightly less NF so in its position near the antenna, works 
better for very weak signals, but the PR6-10 fed thru the 7/8-inch 
line is very close in performance.  Both have enabled me to copy 6m 
eme signals with the single 6-element 6m yagi.

This is largely because sky noise (which includes neighborhood noise) 
is high on 6m which limits the effectiveness of a low noise 
preamp.  Within the 6m eme community its felt that if line loss is 
kept < 1 dB, there is little advantage to placing a low noise preamp 
near the antenna.

In my particular situation I see a slight advantage (too small to 
really be quantified) in having my ARR at the antenna.  I use it vs 
the PR6-10 with that antenna.  I have a 3-element 6m yagi which I use 
the PR6-10 as that antenna is on another coax run. PR6-10 is also 
active on 10m with my triband yagi.

So if you can place a low noise preamp at the antenna, that is ideal, 
but if you run low loss cable having it at the radio is almost as good.

Not sure why anyone would run a cable with 3-dB loss for any 
reason?  Half your transmit power is turned into heating the coax 
(unless you need a cheap dummy load?).

I run 6m-eme with my KXPA100 driving a surplus TV amp (Harris) with 
11w for 1000w output.  I run the K3 at 1.7w with 3-dB attn applied on 
the KXPA100 to achieve 11w output.  I use DIGIOUT1 to switch the PR6-10 on/off.

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