[A-DX] D-Day Special Ute Comms

["Thomas M. Rösner" <dl8aam@xxxxxx>]

Hi,

habe das in einer anderen Liste gefunden, ggf. für
den einen oder anderen unter uns auch von Interesse ?

Interessant ist der Hinweis 'Security restrictions prevented 
from sharing any of this information prior...', scheinbar hatten
die Allierten Befürchtungen "unseren Leuten" auf dem Atlantik Wall 
Hinweise zu geben, dass und wo der D-Day bevor steht,
wie heisst es so schön jedes Jahr Silvester "Same procedure
as 60years before" oder so ;-)

Schade für die Hard-Core-QSLers unter uns, mir inklusive 
"Ich Ich Ich - QSL mir, aber Hopp hopp", gieeeer, lechtz, geier ...hi

Vielleicht ist unser Secret Service nächstes mal erfolgreicher ;-)

73, Tom
DL8AAM

Hoffe die Mail ist noch politisch korrekt ?!?  ;-)

------ Original message:

>Message 24:
>To: <ukfivemegs@xxxxxxxxxxxxxxx>
>From: "Richard Hankins" <trh01@xxxxxxxxxxxxxxxxxxxxxx>
>Mailing-List: list ukfivemegs@xxxxxxxxxxxxxxx; contact ukfivemegs-owner@yahoogro
>List-Unsubscribe: <mailto:ukfivemegs-unsubscribe@xxxxxxxxxxxxxxx>
>Date: Fri, 11 Jun 2004 14:31:23 +0100
>Subject: [ukfivemegs] D-Day stations using NVI
>
>Folks,
>
>you may be interested to know about the military net that I took part in as
>part of the D-Day commemorations this last weekend.  Stations involved were
>using wartime equipment under wartime conditions (as far as possible).
>Security restrictions prevented from sharing any of this information prior
>to or during the event.
>
>Our main frequency used was just below FB (5280kHz) and AM was used
>throughout (this was the only speech mode available to the British Army at
>the time) - to allow members of the public to hear any traffic passed.   Any
>(UK) amateur station operating on FB could not have failed to notice our
>presence - I wonder if anyone on this list actually did?
>
>We also had frequencies near 4.8, 3.3 and 2.7MHz, plus of course 160m, 80,
>and 40m bands.   Aerials were mostly dipoles at a range of heights from 15
>to 40' agl.   Stations involved were:
>
>
>Callsign        Location                                       Equipment
>
>0                 Nutley, Sussex                                Wireless Set No.53. 
>                                             Output 250W of carrier.  Aerial Wyndom about 30' agl.
>21B             Gold Beach, Normandy.                    Wireless Set No.19.
>                                             Output 2W of carrier. Aerial dipole at ??
>22B             Gold Beach, Normandy.                    Equipment unknown.
>32               Portsmouth near coast                     Wireless Set No.19 
>                                              High Power.  Output 15W carrier. Aerial extended Zepp
>34               Monmouth, Wales                            Wireless Set No.19 
>                                              High Power.  Output 35W carrier.  Aerial dipole 37'agl.
>47               Imperial War Museum, Duxford          Wireless Set No.19. Output 2W carrier.
>48               Shropshire                                       Equipment unknown.
>60               Andover                                           Wireless Set No.19. Aerial dipole.
>                           
>
>
>Results on 5.3MHz
>
>I was operating callsign 34.  Noise levels at our station - which was
>located in a field about 1/2 mile from Monmouth town centre, were extremely
>low.   You had to wind the volume up to uncomfortable levels just to hear
>the background at all!.   This was probably typical of conditions back in
>1940, of course, with the lack of electronic widgets polluting the spectrum
>such as we have now in nearly all populated areas.
>
>Our station at Monmouth consisted of the WS19, the Amplifier RF No.2, which
>used fourt 807 valves, running with 600V on the anodes from the internal
>dynamotor which can supply up to 250mA.  It has no trouble with 40W carrier
>output - or about 150W PEP on speech peaks.   All equipment was as original,
>of course - though restored where absolutely necessary to working condition
>(this means a few Rs and Cs have been replaced).  The aerial was a half wave
>dipole, held up at the centre by a 27' mast mounted on the roof of an Austin
>K9 radio truck - giving us a height of 37' in all - the ends were at 27'
>agl.   The SWR on the aerial at 5.3MHz measured a very creditable 1.2:1 (50
>ohms).
>
>Results were that consistent communications were achieved with all stations
>except 21B and 22B.   This was also true if we switched off our linear
>amplifier and reduced power output to a mere 2 watts.
>
>Hearing the guys on Gold Beach was difficult at all times from Monmouth.
>Their signals strengths (subjective) varied from S1 to S3.   At best I could
>hear 21B reading back my mobile phone number - so communication was
>definitely possible.   On CW, comms would have been straightforward at all
>times - that is to say, we could always detect their carrier reliably.  A
>"feature" of the standard WS19 is that the modulation level is very low -
>typically 30% mod depth at best - this means that the speech power was
>around 100mW from the guys on Gold Beach.
>
>Reports from 21B and 22B (Gold Beach) for the UK stations was that they were
>mostly OK  - certainly the station at Monmouth was given good readability in
>Normandy.
>
>Only one station had reliable comms both ways on AM to the guys in Normandy,
>and this was 32.  He was located near the beach, and I strongly suspect that
>they were operating on ground wave across the sea path - which they
>estimated at 100 miles in length.   Relaying messages from 21B/22B was
>reliable via station 32.
>
>Results on 4.8MHz
>
>Communications on this frequency were the same as at 5.3MHz.
>
>Results at other frequencies
>
>I ran a test with callsign 0 on Monday 7th June, to compare the available
>frequencies.   We started at 5.3MHz and worked downwards.  Time as about
>1100 hrs BST at the start.  Temperatures were high (and uncomfortable!) -
>the sun was fierce.
>
>Results on 5.3 and 4.8MHz were identical, that is callsigns 0 and 34 were
>R5, S9++ both ways.  When I switched off my linear, and reduced power to 2
>watts, 0 gave me R5 S7.   At 3.3MHz, I gave callsign 0 R5, S6 - he gave us
>R1 S3 - in other words we could only work on AM one way.  CW was fine both
>ways.   Plainly the D-layer absorbtion was sufficient to cause problems at
>that time of day.
>
>We did not try 40m due to lack of available space, but we noted plenty of
>G-stations active on the band during the middle of the day (Monday),
>suggesting that NVIS was fine at 7.1MHz, and thus the MUF was also at or
>above 7.1MHz.
>
>Results on other aerials
>
>At station 34, we had a choice of the dipole described, plus an 88' long
>wire at 30' agl with ground radials.   A brief test was run with the long
>wire antenna - reported signal strengths dropped about 2 S-points.   As
>these were subjective S-readings, no-one should read anything into the
>magnitude of the drop - but merely note that long wires do not work as well
>as a dipole under realistic field conditions.   If we had been able to bury
>an extensive ground mat, we might have attained similar results to the
>dipole.
>
>(In due course, I will be able to report the actual difference in dBs
>between the signals levels of the 250W station on 5.3, 4.8 and 3.3MHz - once
>I get the WS19 in question on the bench and can "calibrate" its AVC meter.)
>
>
>Conclusions
>
>1.  NVIS from UK to Normandy was easy during the daytime using frequencies
>
>lines 131-153 
>
>around 5MHz, and readily available wireless equipment in 1940.  (The WS19
>was probably the "most available" set at that time.).  Use of CW would have
>overcome all the difficulties we experiences with the much less efficient
>AM.
>
>2.  You get a wider choice of frequency if you have more Tx power.   With
>35W we could have used any frequency from 4.8MHz to 7.1MHz (possibly wider,
>but not tested).   With 250W power, this choice was extended downwards to at
>least 3.3MHz - due to the ability of the higher power station to overcome
>the increased D-layer absorbtion losses at the lower frequencies).  This
>could well have been important in the congested HF bands during the war
>years.
>
>3.  Dipoles are better than long wires, if the only ground system is a
>number of wires laid on top of the ground.  (Might be better with a ground
>mat, but that was not tested).
>
>
>73s
>
>Richard
>G7RVI

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