[TowerTalk] Perplexing Antenna Problem
wtrone at comcast.net
Sat Aug 28 21:38:20 EDT 2004
The tower is folded over. The antenna is almost vertical and the
measurements are made in the 180 degree mode. If I tune in on a strong
signal, say on 20M, and then do a calibrate, you can see the signal strength
go almost to zero and then build back up.
----- Original Message -----
From: <kk9a at arrl.net>
To: <towertalk at contesting.com>
Sent: Saturday, August 28, 2004 6:58 PM
Subject: Re: [TowerTalk] Perplexing Antenna Problem
> The problem appears to be in the antenna. Are the received signals strong
> and does it appear to have a proper beam pattern when you rotate it?
> (callsign) KK9A
> ----- Original Message -----
> From: "Bernard(wtrone)" <wtrone at comcast.net>
> To: <towertalk at contesting.com>
> Sent: Saturday, August 28, 2004 19:40
> Subject: [TowerTalk] Perplexing Antenna Problem
> I posted the following message on the Yahoo SteppIR board and thought
> that I might also get some ideas on this board.
> I have an interesting problem for all of you antenna experts out there.
> you have been reading this thread (Yahoo SteppIR board), you know that I
> have been having problems with my new SteppIR 3 element beam. I was able
> borrow a MFJ-259B this morning and made a relatively extensive set of
> measurement, which taken as a whole, just do not make sense.
> In summary (2 measurements on 20, 1 on 17, 2 on 15, 1 on 12 and 2
> 10M for each series of readings):
> 1. Set of measurements using the MFJ with a 20" length of coax
> to the SteppIR. Measured from 20-10M SWRs of from 1.5:1 to 1:1 (also have
> the R and X measurements but won't go into those just yet).
> 2. Set of measurements using the MFJ in the shack using the
> length of cable to the SteppIR. Measured from 20-10M SWRs of from 1.4:1
> 3. Using MFJ to measure Coax Loss from 20-10M showed 1.3 to
> dB. Probably about 135 ft of cable.
> 4. Put the cable in the shack directly on the antenna
> of a Daiwa NS-660PA SWR and Power Meter, and the SWR is 5:1 from 20-10M.
> The reading on the TenTec Orion is high VSWR. Take the PL-259 off the
> SteppIR and put it on a 50 ohm dummy load and the SWR is a flat 1:1 across
> 20-10M both on the Daiwa and Orion.
> 5. Tried varying the "tune" power of the Orion from about 1
> to 50 watts. No difference.
> 6. Tried taking the Daiwa out of the circuit. No difference.
> Orion still reads high VSWR.
> 7. Swapped out a complete set of coax cables to insure nothing
> was common. No difference.
> Anyone out there in radio land have any ideas? I am going to talk to
> Jim on Monday, but this is really a STRANGE set of data. I am a bit
> perplexed with what I am seeing!
> Bernard, WA4OEJ
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> questions and ask for Sherman, W2FLA.
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