[600MRG] Additional comments to Ed's side note - was Unusual Propagation

[John Langridge]

RR!  Great info.  I may want to pick your brain a little more going forward on this experiment and preparing the presentation.  There is safety in numbers!


This is exactly the kind of info that needs to be out in the public discussions.  Here locally there is a very myopic view of emcomm that does not involve 2m FM.

73,

John XIQ  



________________________________
 From: Edward R Cole <kl7uw at acsalaska.net>
To: John Langridge <jlangridge at sbcglobal.net>; "600mrg at w7ekb.com" <600mrg at w7ekb.com> 
Sent: Sunday, January 5, 2014 7:50 PM
Subject: Re: [600MRG] Additional comments to Ed's side note - was  Unusual Propagation
 

Thanks, John.

What we found in about 3-4 months running CW one-way from my station with 100w output (ERP=4.15w) my signal was copied by Laurence in Wasilla roughly 100mi at 35 to 45 dB over noise measured using spectrum sw.  Most of the time the higher number.  If SNR=0 is taken as S-0 then 45-dB is S-7.5.

Laurence will have to comment what the noise floor ran and his receiving antenna+reciever.

Two-way CW with Roger, KL7Q, was very easy.  Roger and Laurence are only a few miles apart.

So 100w = 50 dBm, if you subtract about 30-dB then 20-dBm = 1w would have an SNR of 15-dB.

So even a low power transmitter and small portable antenna would work out to 100mi.  This is commonly the distance emcomm needs in a mass disaster.  We have a wide-area exercise coming up in March.  It would be interesting to see if our outlying HF stations could copy my 100w home station on 495-KHz.

73, Ed - KL7UW

At 03:32 PM 1/5/2014, John Langridge wrote:
> KL7UW said:
> 
> "Sidenote: at a recent ham club meeting a ham asked my opinion of using
> LF ground wave for emcomm out to about 100-mi.  I suggested 600m would
> be easier than 2200m in as far as temp antenna and I have proven 100-mi
> ground-wave is 100% reliable 24/7 x 365 in 2010 tests conducted with
> KL7Q (/28) and WE2XPQ (we enjoy absence of summer static crashes up
> here).  Currently, 80/40m SSB is used for emcomm links between our major communities, but that is too subject to variable prop.  VHF is blocked
> by several mountain ranges.  On MW we would probably look at a
> text-based digital mode for even better SNR."
> 
> I wanted to add to Ed's emcomm band selection comments above that I have been doing some testing with a very small antenna on 630m, literally a smaller than half sized - G5RV configured as a marconi T (but the horizontal parts are sloping at 45 degrees) with a variometer at the feed point and a minimal number of short radials.  Running about 10 watts from a U3 and small amp, it was heard reliably with room to spare  near Oklahoma city by K5UV and WG2XXM last week.  I'm still looking at the numbers but it seems like the ERP was somewhere between .1 and .01 mW..  Those guys are about 200 miles North of me and had copies in the low -20's... unreal...I admit that I am currently fighting a RF problem due to poor grounding but in concept its working!
> 
> 
> Anyway, I just wanted to add those comments because I am planning to give some talks on this very subject targeting the emcomm crowd regarding how a simple, average (or below average) ham system that can work on 630m this summer as I had a lot of guys comment last year that I was successful on the band because I had a large antenna, a lot of power and a lot of radials and that they could never see similar success with their existing setups... Its kinda funny how the repeater crowd gets lulled into that kind of thinking...lots of possibility for emcomm guys on MF with keyboard modes as a backup when the repeaters go down.
> 
> 73 all.. lets hope for good things this evening!  CW from here at 0200Z at 474.5 +/- for 15 to 20 minutes.
> 
> John WG2XIQ
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73, Ed - KL7UW
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