[NLRS] 70-cm Antenna Dilemma - Part II

[Carl Estey]

Many thanks to everyone who responded.  Here is the collective knowledge I
gained from all of the responses and some answers to your comments.

The consensus is that that the unknown antenna is a KLM 440-16X.  That is
correct - and I confirmed this from a 1995 AES catalog.  I do have a KLM
440-16X.  The specifications shown are:
Bandwidth - 420-450 Mhz
Gain - 14.0 dBd
F/B - Greater than 20 dB
Balun - Coax "N" 4:1 2kW
Beam - E = 28 deg; H = 32 deg.
Boom Length - 10 ft 3 in

The 19th edition of the ARRL Antenna Book does have a large amount of info
on various K1FO antennas however the 70-cm version is only 22 elements - and
what I have is 25.  I still need data on the 25-element version.

There was a suggestion that I try a MFJ antenna analyzer to check the balun.
That would be great but I don't have one.  I do have a MFJ that covers 160 -
144 Mhz but doesn't make it to 432.  Anyone have anything I can borrow?

There was a suggestion that the connector in the radio might have a bad
solder joint.  I would guess that to be unlikely since the radio is a Yaesu
FT-897 and the same connector is used for 2-meters and 70-cm and 2-meters
works well.  

Someone else asked if I am sure the is ok?  The problem is exhibited on both
TX and RX.  The initial test was between Vince, K0VZJ and my station in
Bloomington with results at noise level to a maximum of 4 S-units.  The
second test was with Matt, KA0PQW tonight and the same results - noise level
to S-2.  Also, I noticed that the solid state amplifier SWR warning light
came on.  So the problem is mutual to TX and RX.

There were some other good questions asked - and here are my replies:
Was it the same feedline ?  No - I had the problem with a 66' run of new
LMR-400.  Then I tried a 48' run of Andrews 7/8" heliax.

Same jumpers in the shack ?  No.  A new LMR-400 ultra 15' jumper from the
heliax to the radio.  Same results with a 15' jumper directly to the antenna
at 8' above ground.

Same radio or transverter ?  No.  I did try my Microwave Modules 432-28
transverter and had the same results with Vince, K0VZJ.

Same preamp ?  No external preamp.

How good are you measurements (i.e., 20 dB above the noise) ?  Probably not
good at all as they are based on the Yaesu FT-897 S-Meter and my assumption
that a S-unit equals about 6-dB.

How do you KNOW that you're down 40 to 50 dB ?  Who/what says ?  Like I
said, somewhat guessing.

The K1FO antenna has not made it up the tower yet and the tests were solely
in the backyard from a 8' mast with a 15' LMR-400 jumper to the FT-897.  The
odd thing is that no amount of tuning the T-match got the SWR as shown on
the internal FT-897 meter to get to 1:1.  The best I got was at 430 Mhz.

Where/how did you measure the SWR ?  AT the antenna(s), or at the end of the
feed line in the shack ?  Like I said, the measurements were with the
radio's internal meter.  I do have a Bird 43 and slugs for 440 Mhz so I will
check it out.

Thanks to everyone who responded.  It has given me some things to think
about.

73
Carl Estey WA0CQG
wa0cqg at arrl.net
(952) 250-3110 (Cellphone)