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Reviews Categories | Antennas: HF: Yagi, Quad, Rotary dipole, LPDA | Mosley Pro 67B Help


Reviews Summary for Mosley Pro 67B
Mosley Pro 67B Reviews: 13 Average rating: 4.5/5 MSRP: $$955.00
Description: 40 thru 10 Meter Beam, 7 elements on a 24 foot boom
Product is in production.
More info: http://Mosley@mosley-electronics.com
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AA9HX Rating: 1/5 Jun 18, 2001 17:10 Send this review to a friend
poor design, very bad company !!!  Time owned: more than 12 months
Product Review: Mosley Pro67B 7 element 6 band trap yagi antenna

By Pedro M.J. Wyns ON7WP-AA9HX

Preface: after having used a TH3JRS by Hygain for about ten years, I moved to a new house and while waiting 2.5 years for a tower permit I restored and used a Cushcraft A4S. When the license arrived I wanted a single multiband antenna for HF as my tower is already loaded with 8 beams for VHF-UHF and 4 omnidirectional antennas...
Another Ham had to sell his 4 year old PRO67B because he lived in the middle of the city of Gent and his new neighbours didn't appreciate the faeces of the multiple birds residing on the beam...

Primary inspection:
Upon arrival the antenna looked OK except for the two plastic rings of the gaying cable attachment to the boom. I also discovered that in contrary to the brochures of Mosley not all the parts were stainless steel, and the penalty for this significant error is heavy corrosion at all lockwashers and at the feedline and phasing line connection.
I also checked all connections and first I must say that Penatrox is a great product inhibiting the typical aluminium-on-aluminium white powder corrosion rendering all connections bad. The alu joints were just perfect after 4 years in our polluted sky. The traps however showed BIG resistances, traced to the joint between the coil and the rivet inside the trap. Alu-on-alu without Penatrox. Perhaps it would have been a better choice using a SS bolt instead of this rivet. I replaced it anyhow. I decided to write the guys at Mosley a letter using E-mail, perhaps too progressive for a company that calls itself conventional...

After these findings, I did send the following letter to Mosley and did not get any response until now...

From Pedro M.J. Wyns, July 17th 2000

Moutstraat 7
B-2220 Hallaar
Belgium Europe
Fax +3215409696
E-mail aa9hx@arrl.net


Some comments on your antennas is order to improve your products:

I recently acquired a pro-67-B ser. 563001 that was up in the air for about three years in a Belgian urban area. Before reinstalling it at my home I thoroughly checked the whole thing and the results were frightening...

The antenna is sold as being all stainless steel however al lock washers were totally oxidized and also completely contaminated the surrounding screws and U-bolts. Please use only similar materials, DO NOT MIX stainless steel with ordinary zinc-stuff.

Checking the traps with a milliohm meter revealed two major defects. First the contact between the trap and the element is only made with a single self tapping screw. Slightly moving the element revealed transfer resistances between 0.5 and 15 ohms, sometimes completely losing contact. Hard wind makes the antenna completely useless. I would suggest replacing the self tappers by a completely through the element bolt, or better two spaced 90 degrees apart with a slight offset.
The second frightening experience was the trap resistance of the rear driven element itself, one was 27 ohms the other 13. The problem was in both cases isolated to the 17 meter trap side. The trap looked fine inside but apparently there was a bad contact between the coil and the rivet, the rivet itself gave good contact to the carrier-tube. I replaced it by a stainless steel bolt, although I have no explanation why I only found this problem at BOTH 17 meter trap-sides.

In Europe every serious operator is using for these antennas 60 mm tower tubes. Please use a decent tower plate not just for toy 2 inch tubes...

You should also include a European code II setting, this is identical to your manual except for the two elements working on 40 meter. The 40 meter end tip must be set here for the longest option as our band stops at 7.100 and nobody can use an antenna that is resonant at 7.200.

I hope my comments are useful for you in order to improve a nice design that however has some serious mechanical/electrical defects. German designs and even the new Cushcraft is much better on the mechanical side so don't stay behind.

I am planning to publish an article on my findings and would appreciate your feedback to include with the article.

One final question perhaps. Why is the manual stating that one should NOT use a balun. I see no harm in using for instance the Radio Works current balun, in contrary. It can my opinion only improve the radiation pattern. Air coils are in recent findings completely turned down as ineffective.

Thanks for your time, and keep up the GOOD work, improve the bad...

Pedro M.J. Wyns
ON7WP - AA9HX

As I got no reply I decided to put up the repaired antenna temporary on my testing-tower. (yes we are so lucky to posses an ex-military 18 meter steel crank-up tubular tower.) I rose the antenna up to the 10 meter level and got the following results:
To check the pattern for F/B I parked my car containing a very old IC-706 and a Comet CA-HV 40-20-10 meter antenna about 300 meter from this tower and used my bicycle to travel back and forth in order to adjust frequencies...
There are no results for 12 meter as the antenna did not resonate on that band. However the traps were checked with my Autek RF-one, a hell of a great tool...
My FT-1000D was relocated to the garden table as a field measuring tool. SWR was measured by the on-board meter as well as an external Daiwa device, but these were almost indicating similar values.

The 12 meter VSWR problem was solved after changing the cable length...apparently I was just unlucky to have an uneven multiple of quarter waves between the antenna and my trx. I suppose impedance was slightly offset from 50 ohms and worse due to cable transformation. Since it is on the tower the problem of high VSWR moved to 10 meters probably due to the close proximity of the VHF array. I'll check the impedance on all bands at the antenna terminals when I'll be up on the tower again.
The first contacts are promising but I still suspect the antenna of poor F/R performance. I'll make a test setup at my other QTH 2 miles further away and will redo the tests with this signal source.

 
K0PZ Rating: 5/5 May 11, 2001 17:23 Send this review to a friend
Good Investment  Time owned: more than 12 months
I have had my PRO 67B for almost ten years. I purchased it when the ?B? version first
came out. I previously had a Cush Craft A3 with the forty meter kit. When the antenna
arrived, I took a inventory of the parts that came in the two boxes. To my pleasant surprise they were ALL there. There are a lot of parts so I laid them out in order of which element , section of boom and so on. Next I checked for burrs and deburred as necessary.
Assembly took about five or so hours. I assembled one element at a time and set it in order of boom location. This antenna is BIG when it is setting at ground level.
It weighs about 110 lbs. The manual was well laid out and the tuning went by the book.
With the antenna at 60 ft. the SWR are very close to the book. Front to Back seems about book also. When listening on 40 meters you can tell the gain is about book also by rotating to peak and rotating 180 deg. I am very impressed with this antenna.
The performance is as published on all bands that it is designed for. Quality is superb.
This was a very good investment and I am still happy with it.

73
Bob
 
WT8Y Rating: 5/5 Feb 21, 2001 09:41 Send this review to a friend
Good All Around Performer  Time owned: more than 12 months
I have used the Pro67B for 5 years and been pleased with it's performance. At 70 feet I never take a backseat to the neighborhood "Mono Banders"
There are 4 Pro 67B's in the local area and we all have good words for the product. Strong and reliable.
 
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