[Milsurplus] Fw: NVIS vs Ground Wave again

[Al Klase]

Hue and the Group,

Take a careful look at the half-wavish end fed "reel" antenna in the 
GRC-9 TM, then try to tell me they weren't using NVIS.  That wasn't what 
they called it, but it's what everyone did for regional coverage on, for 
instance, the 80 and 40-meter ham bands.  This mode of operation of the 
Angry-9 was exploited by the US Army in cold-war europe as the developed 
the Long-Range-Reconnisance-Patrol doctrine.

Al

On 5/13/2012 3:46 PM, Hue Miller wrote:
> [ FWD from Armyradios group ]
>
> -----Original Message-----
> From: Hue Miller
> Sent: Sunday, May 13, 2012 12:45 PM
> To: armyradios at yahoogroups.com
> Subject: NVIS vs Ground Wave again
>
> A discussion group for those who collect>>  Gang,
>>> Subject header says it all. I'd really like to understand why
>>> transmitters
>>> chirp when they send code, and if anybody has ever been successful in
>>> modifying an AN/GRC-9 to make it legal.
>>>
>>> Thanks in advance.
>>>
>>> By the way, I know this has been said on the group before, but I'm pretty
>>> sure these radios were not used to send NVIS signals. I think it was
>>> sometime after our involvement in the Vietnam War that the concept came
>>> into vogue. I do know that the division operating area was much smaller
>>> during the Korean War and I suspect they just used groundwave propagation
>>> with the long wire antenna and counterpoise set. (Dennis, care to correct
>>> the self-appointed "expert"?)
>>>
>>> Sean
> Sean, you didn't really mean to use "legal", did you, unless for humor and I
> missed
> it?
>
> A tidbit for you: a former military user of the SCR-131 told me that on
> field
> maneuvers they would sometimes use a wire dipole with the SCR-131 to
> gain more distance. The wires were tapped onto the SCR-131 loop antenna
> using something like battery jumper clamps, on one side of the loop, and
> spacing adjusted for best impedance match. I think he said something like
> 35 miles range, day, with this.
>
> An anecdote re NVIS and ground wave: on a recent walk around the bayfront
> of Newport, Oregon, I discovered the city had installed new sidewalks where
> there had previously only been a dirt trail next to a road by the the USCG
> station. ( U.S. Coast Guard ). At quite a bit of expense I imagine, the city
> had
> made part of the sidewalk wheelchair accessible, via ramps beside the
> stairs,
> even on part of the walkway that just seemed to deadhead to a beach walkway
> that is really too rocky for wheechair travel - but maybe I'm wrong on that.
> Anyway the new walkway is higher on the hillside, and you can see better
> down into the parking lot area of the CG station. And the small building
> on whose roof is the USCG information radio on 1610 kHz.  The antenna is
> about a 15 foot mast. The transmitter apparently is contained in a box about
> 12 x 12 x 6 inches - my guess. ( This story DOES have a point. ) Now with
> the
> raised walkway, you can better see what's going on with the antenna, and
> how it's grounded - you can see the ground network on the roof, and it's an
> 'umbrella' pattern of wires radiating out from the transmitter box over the
> roof.
> The roof is not that large, I think maybe 20 x 20 ft. At the transmitter
> end,
> the wires all attach to a hoop wire about the diameter of a basketball hoop.
> I'd guess maybe 20-30 of those rather short ground radials. I think I'm
> going
> to try to later get a photo for Popular Communications magazine because
> it's rarely that you get to see what's going on with the ground system of
> such an operation.
> I don't think these stations run much more than about 10 watts, but I don't
> know whether that's in or out.
> Anyway, I found on my work truck radio, I can copy this broadcast out to
> about 8 miles, and that includes over the coastal hill range. It's not
> broadcast quality for the usual civilian but DX-able level for a radio
> fanatic.
> CW of course would increase that range and make copy at this distance
> 100%. The terrain is hilly and rocky and very thickly forested.
> Now the payload.  As I was DXing this, seeing how far I could hear it, I
> was reminded of German WW2 vehicular communications in the 1 - 3
> MHz range. I had read this was to exploit ground wave coverage in
> typical rolling European country. I also recalled reading in QST
> antenna book a comparison of signal strengths of mobile 160 and 80
> meter transmitters. The article said 160 actually gave better range,
> due to ground wave coverage, even with the substantially greater
> antenna inefficiency at 160 meters. I do NOT at all believe my
> experience had anything to do with NVIS propagation - if it did,
> I believe the signal strength would not obviously fluctuate with
> the lay of the land. I was quite impressed with the distance range
> I heard the USCG station at, especially as it's at sea level and
> the landward route is all uphill, shaded by steep uphill grade.
> -Hue Miller
>
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/