Rhombic antenna "gain"

[Phil Kane-2]

On 9/14/2019 9:53 AM, Mike Markowski wrote:
> I took some photos as the shut down was under way in 2011. I wish I had
> taken some sooner, even a week earlier. They're at:
>
> http://udel.edu/~mm/ham/monmouth

Mike, thanks for posting those pics.  Although I was never involved in
MARS, the barracks building as shown was a carbon copy of the one that
housed my project office for the installation and turn-over phases of
the Strategic Air Command Control System at March AFB (Riverside, CA)
where I "held forth" from January 1963 to July 1964.  Our inside spaces,
though, were far less luxurious than that of K2USA.  :)  The actual
SACCS equipment, though, was in a brand-new command post building across
the street.  All gone now, I understand.

73 de K2ASP - Phil Kane
Elecraft K2/100   s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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[David Olean]

Hi Wes,

You forgot to mention that Chris VK5MC was only running 150 watts
output. His pattern dropped off drastically as the moon exited his
window. When I built my humongous 144 MHz array in 1979/80, I figured
that my window with VK5MC would be a bit wider with the added gain from
the 24 yagi array.  It hardly varied at all! He just got louder when I
could hear him. I might have picked up one minute.  Great fun thinking
about those times! Thanks.

To make this Elecraft related, I wish I had a K3 for my EME receiver
instead of the Collins 75A4 that I was using back then. The APF would be
fantastic on CW EME. It would have saved me a lot of time modifying the
A4 to make it better!!  I replaced the 6BA7 mixers with 6DJ8s. I took
out an IF can and dropped in an R-390A 2.0 kHz mechanical filter. I had
to add a 2N4416 FET to account for the added loss in the filter. The
last big mod was to add another Collins 300 Hz crystal filter in the CW
fillter position. I jury rigged it underneath the chassis on a bracket.
I still have the 75A4 and did a cap replacement last winter. It had not
been fired up since about 1992. It needed work. After it was all working
fine again, I checked MDS  (-138 dBm) and close in dynamic range at 2
kHz. I saw 92 dB which is not too shabby and in a different league than
a stock A4. Still it is a good 10 dB below the K3.

Dave K1WHS

On 9/14/2019 12:09 PM, Wes wrote:

> I completed my 2-meter WAC by working VK5MC on December 3, 1982. Chris
> was using a rhombic, IIRC, 50 wavelengths on a leg and more-or-less
> fixed on his rising moon.  I believe with some ropes he could "steer"
> one end to get a few minutes more on another couple of days a month of
> use.  Otherwise it was a pretty short window.  Modern Yagi designs
> blow these away.
>
> Wes  N7WS
>
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[Lyn WØLEN]

Don -

Thanks for your input.  I should have gone into more detail.

We did sustain a direct (yes, direct ...) lightning strike on our house in March, 2012.  A freak storm after a week of 80F+ temps in Chicago.  Lightning struck an attic roof fan, followed the wiring to the basement, and did nearly $100k damage to the house.  I had NO antennas of any type up at that time.

But I did subsequently have lightning protection professionally installed, consisting of a number of lightning rods on the roof all connected inside along the ridge line with 00 gauge stranded copper, running to 10 foot ground rods at both ends of the house.

This wire runs well above the G5RV in the attic ... far enough to protect it and also far enough to 'not' act as a Faraday Cage.

Would another direct strike still cause issues? Possibly, but I feel much more secure with that antenna in a storm than the outside EDZ.

73,
Lyn, WØLEN


-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Saturday, September 14, 2019 8:51 AM
To: [hidden email]; 'Elecraft Reflector'
Subject: Re: [Elecraft] Rhombic antenna "gain"

Lyn,

Hopefully you do not trust that an antenna in the attic will not be
susceptible to lightning.
I would not use ANY antenna during a thunderstorm.
Shut down the station and ground all feedlines.

73,
Don W3FPR

On 9/14/2019 8:27 AM, Lyn Norstad wrote:

>
> Prior to the HOA changes, I was limited to a G5RV Jr. in the attic.  It
> worked fairly well, but nothing like this.  I still use it as a backup
> during thunderstorms when the EDZ is disconnected.

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