[Towertalk] Tribander anomaly

[Bill Hider (N3RR)]

Before you blame or compliment an antenna, determine the complete loss/gain
including feedline losses.

Be sure you're not overlooking something in the system.
Are all three antennas pointing in the proper direction?
Is there additional feedline loss in the A4S antennas?

Also, as I read your posting:

402CD @ 70 ft above ground on roof-tower
A4S @ 58 ft on same roof tower (closer to the roof - too close? how close?)
A4S @ 52 ft on another mast not on the roof.

Is it possible that the proximity to the roof of A4S #1 and the 18 ft lower
position of A4S #2 causes both antennas to be
6 dB (1 S-unit) less in signal level from the 402CD?  Again, check the line
losses to be sure we're apples-to-apples.

Is there anything in the system? - antenna relays?  different antenna
switches?

Bill, N3RR





----- Original Message -----
From: "W4ZW" <w4zw@comcast.net>
To: <towertalk@contesting.com>
Sent: Wednesday, May 08, 2002 4:01 PM
Subject: [Towertalk] Tribander anomaly


>
> I have an antenna/tower question for a change of pace.
>
> I discovered quite by accident that 15M signals are better on my 402CD
> CC 40M beam  than on either of the A4S tribanders I currently have up.
>
> I was listening  to a pileup the other evening on 15m and realized I was
> on the 402CD.  Switched to the A4S which is 12' below it and the signals
> dropped a full S unit.  Wow, that's strange.  I just recently rebuilt
> all the antennas that were pretty much destroyed in a tropical storm.
> New aluminum, hardware and feed lines.
>
> The 402CD is rebuilt and on a Glen Martin rooftop tower about 70' above
> ground which is about 18' above sea level in my back yard.  I'm ocean
> front directly on the Gulf of Mexico on the southern tip of an island
> with ocean and bay in all directions except NNW.
>
> I switched to my second A4S (not rebuilt, but one I kept in the garage
> for Field Day) that is on a Rohn mast about 6' lower than the first A4S
> and about 35' away  to the SSE.  Same signal level as the first A4S.
> Switched back to the 402CD and the DX signals pop up out of the noise.
> Does the capture area of the 402CD make that much difference?  My wire
> antennas are still down so I can't compare there, but as soon as the 80M
> Bob tail and the full wave delta loop are be back up I intend to explore
> them as well.
>
> SWR on both the A4S's are essentially flat 1:1.  They are super on 10
> and 20 compared to the 402CD, but on 15M the 40CD2 is clearly the better
> receiving antenna.    The 402CD has a 2.6:1 SWR on 15M and is easily
> loaded with the auto-tuner on the FT-1000D.  Of course it loads pretty
> well on 12M and 17M as well.  Maybe the 402CD should be called a
> quadbander, hi!
>
> Any ideas?
>
>
> Jon Hamlet,  W4ZW
> Casey Key Island, FL
>
> "A little bit of Paradise in the Gulf of Mexico"
>
>
>
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk



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