[TowerTalk] antenna choices for K4XS

[Stan Stockton]

It is worth reading the post with full text below from N0AX, one of the report authors, from a year and a half ago written during another round of opinions regarding Mosley antennas.

I've read all these posts and have a few observations.  I don't own a commercial antenna and don't plan to buy one anytime soon.  I'll stop short of calling it bashing but will say that it appears there is a lot of unfair bias in regards to Mosley.

W4TV wrote:  

>K7LXC and N0AX published two widely respected *scientific* studies
>of tribander performance using validated measurement techniques to
>directly compare the performance of the tested antennas against a
>standard (dipole).  

N0AX wrote:

>The main issue with the Mosley PRO antennas we tested was on 10 meters 
>where gain and pattern were definitely below spec.  It is quite possible 
>that the manual's instruction not to use a balun at the feed point 
>allowed significant feed line interaction to the point of upsetting the 
>radiation pattern.  All other antennas did use a ferrite bead balun made 
>by Force 12.  We did not test the Mosleys with and without a balun - 
>there wasn't enough time and energy.

And VE7RF wrote:

##  Oh this just cracks me right up !   Megabuck Mosley PRO 57 / 77
has essentially no gain on any band.  
The kicker is.... the PRO-57/77 has LESS  gain on 10m  vs the paltry
TA-33 !!!     WTF ?    

##  I mean..come on folks.   LESS than 1 db gain on 20M.....vs a dipole  for the 57/77 . 
57/77  has NEGATIVE GAIN on 10M.....by > 1 db.....vs a dipole. 

N0AX wrote regarding the Mosley PRO series:

>On the other bands tested (20 and 15 meters) they performed more or less 
>in line with what you would expect from their boom length as did other 
>tribanders such as the KT34XA, C31XR, TH11DX, Skyhawk, etc.

For W4TV......While taking a huge amount of time and effort to do "two, widely respected "scientific" studies" of TEN different triband antennas in order to publish a report that is still being sold sixteen years later, according to N0AX there "wasn't enough time and energy" to put a choke or balun on even one Mosley antenna when feedline radiation would be or was suspect in causing the performance to be less than that of a dipole that DID have a feedline choke installed.   As VE7RF would say...WTF?

For VE7RF..... Does the report really say the 55/77 has less than 1 dB gain on 20m as compared to a dipole when Ward says the issue was on 10m and like the C31XR, SkyHawk, etc they performed more or less as expected according to the boom length on 20 and 15? If what you and Ward say are both true, what does that say about the C31XR and SkyHawk?  

For K9YC....  If, like the C31XR, SkyHawk, etc, the Mosley antennas performed as expected for boom length on 20 and 15, I wonder how they might have performed if they had one of your chokes instead of having the coax directly connected to the driven element?

73...Stan, K5GO


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Ward
Silver
Sent: Mittwoch, 4. Dezember 2013 05:12
To: towertalk at contesting.com
Subject: [TowerTalk] Clarifying on Mosley

As one of the report authors, I thought I should jump in here.

The antennas were working models, borrowed from their owners for the 
tests, and assembled following the manufacturer directions to the 
letter.  The antennas were returned to the owners and reinstalled, 
continuing to be used on the air with no reports of significant 
failures.  After a first test indicated problems with a PRO-57 we 
offered to test a new antenna from Mosley in the second round but they 
declined for whatever reason.

The main issue with the Mosley PRO antennas we tested was on 10 meters 
where gain and pattern were definitely below spec.  It is quite possible 
that the manual's instruction not to use a balun at the feed point 
allowed significant feed line interaction to the point of upsetting the 
radiation pattern.  All other antennas did use a ferrite bead balun made 
by Force 12.  We did not test the Mosleys with and without a balun - 
there wasn't enough time and energy.

On the other bands tested (20 and 15 meters) they performed more or less 
in line with what you would expect from their boom length as did other 
tribanders such as the KT34XA, C31XR, TH11DX, Skyhawk, etc.

It would not be fair to characterize Mosleys as chronic underperformers 
across the board - numerous stations report good results from them.  For 
example, K4RO has a pair of PRO-57 beams and does quite well (his QTH 
has some rather dramatic topography to work with).   I don't see a lot 
of Top Ten stations using them and you can read into that whatever you 
want.  Although the electrical designs are pretty long in the tooth, the 
antennas are sturdy and robust - they stay up and withstand the elements 
pretty well.  There are other considerations such as operating bandwidth 
or wind speed rating that might be more important than forward gain to 
some customers.  Antenna selection is a complex situation with a lot of 
moving parts.

All of the data and the methodology is published in the report. I've 
wished another group would tackle reproducing the results but this is, 
after all, a leisure activity :-)

73, Ward N0AX