[Towertalk] Force 12 needs to do more homework

[RLVZ@aol.com]

Question- 
Will Force 12 do refunds?  I would have returned one if I'd known they'd take 
it back.
Richard- K9OM

In a message dated 5/9/02 9:27:37 AM Eastern Daylight Time, 
ve4xt@mb.sympatico.ca writes:

<< I would expect this degree of fiddling with a homebrew antenna, not
 something "engineered" to the degree of an F12.
 
 Why is this accepted? Send it back and demand a refund.
 
 73, kelly
 ve4xt
 
 
 ----- Original Message -----
 From: <RLVZ@aol.com>
 To: <towertalk@contesting.com>
 Sent: Thursday, May 09, 2002 8:03 AM
 Subject: [Towertalk] Force 12 needs to do more homework
 
 
 > Force 12 needs to do more homework.  It should not be necessary for the
 > consumer to have to do all this work (take the antenna down and modify it
 > several times) to make a mass produced factory built F12 work properly.
 > Richard- K9OM
 >
 >
 > Dink
 >
 > I have a C31XR up at about 70 ft fed with three seperate feeders.  Each
 > antenna is fed with 50m of HD100 coax and each has a choke balun of 12
 turns
 > of coax with a piece of 6 inch dia plastic water pipe as a former so the
 > turns don't bunch up.
 >
 > SWR on all bands is at 1.1:1 or better at my chosen centre frequency.
 These
 > are 14100, 21200, and 28200.  These c/f give me good swr across CW and
 > sideband segments.  To achieve this I removed the tips from the 15m
 > element,added extra length to the 20m element and used hairpin matches on
 > all three driven elements.  These took some fiddling with to achieve best
 > effect.
 >
 > The above swr readings were taken with the feeders to the other two yagis
 > open circuit.  Any kind of load placed across the 20m coax whilst using
 15m
 > messes up the SWR on 15m.  This has caused me a problem in my SO2R set-up
 > which I have worked around by putting a 15m parallel tuned circuit in
 series
 > with the 20m feed.  I used a small L and big C to minimise the effect on
 my
 > 20m SWR.  It's a compromise but it does work.
 >
 > With good choke baluns on each driven element I have found SWR to be
 > substantially independent of feeder length.  That is with 50m and longer
 > feeder I haven't tried with feeders shorter than 50 metres.
 >
 > BTW You did remove the tips from the 15m elements didn't you?  The 15m
 > elements as delivered are too long for the separate feeders option.
 >
 > I have added a Cushcraft XM240 at about 85 feet (turned 90 degrees to the
 > C31XR) and I have inverted vee dipoles for 160m and 80m hung just below
 the
 > C31XR.  None of this seems to have had a materially adverse effect on swr
 or
 > performance of the C31XR so far as I have been able to judge.
 >
 > I hope this helps.
 >
 > 73
 >
 > Bob 5B4AGN >>