[TowerTalk] Telrex Monoband matching

[Paul Cassel]

The 3 antennas I have purchased and am currently assembling are Mono Band
antennas and not the tri-band model.  The model numbers are 10M-532, 15M-532
and 20M-436 - however I appreciate everyone's comments and feedback and
believe the following info to be the answers I was seeking.

What I have learned is the 20m 20M-436 antenna has fixed bolts securing the
first and second portions of each element in a factory fixed length leaving
the tip measurement as the only available variable.  Since the 20m antenna
was totally disassembled this bolt solution rather than a clamped slip
joint, was not obvious looking at the pieces.

Now for the matching - the consensus for the T match is something in the 200
ohm range requiring a 4:1 balun which makes sense based on the type of 1/4
wave coax balun shown in the 10 and 15 metre manuals.   I assume a
commercial ferrite 4:1 balun could be used in place of the 1/4 wave coaxial
originally specified?

I feel very comfortable now using the tip measurements for the various parts
of each band however if anyone feels the feed impedance comment is off-base
I would like to hear from you.

After cleaning all joints and applying conductive grease to all joints. the
10 and 15 beams are fully reassembled so now off to sort out the 20.

Thanks again to everyone who replied on and off the list

Paul VE3SY




> -----Original Message-----
> From: David Jordan [mailto:wa3gin at comcast.net]
> Sent: Monday, July 02, 2007 11:08 AM
> To: NPAlex at aol.com; towertalk at contesting.com; paul at ve3sy.com
> Subject: RE: [TowerTalk] Telrex Monoband matching
> 
> ...the wire is actually inside the balun box (not the 10m trap), but it
> was
> stated to me that the wire was added to improve 10m matching.  I have an
> open one in the country if anyone wants to see the picture of it factory
> untouched let me know.
> 
> 73,
> Dave
> Wa3gin
> 
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of NPAlex at aol.com
> Sent: Sunday, July 01, 2007 11:29 PM
> To: towertalk at contesting.com; paul at ve3sy.com
> Subject: [TowerTalk] Telrex Monoband matching
> 
> Paul,
> 
> A multiband beam and T match are incompatible as the T match is frequency
> specific.  I am not sure what the reference to the 10m gadjet wire is, but
> there was a technique of adding a wire to the inside terminal of the 10m
> trap and "tuning" the trap to adjust the center frequency of the 10m
> driven
> element. This is the "gimmick" approach to small values of capacitance.
> 
> Regards,
> Norm W4QN
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