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

[Edward R Cole]

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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