[TowerTalk] About to pull the trigger

[donovanf at starpower.net]

If you search the Towertalk archives, you'll find some hams (e.g., K7SV) had problems with stacking the KT36XA and the 40M4LLDD.

I'm not sure that the smaller Prosistel is a good choice for turning two large Yagis.  Perhaps some Prosistel owners will comment.

Google is a much more effective search tool than the native contesting.com search tool.

Just do the following Google searches:

KT36XA 40M4LLDD site:contesting.com

and

KT34XA 40M4LLDD site:contesting.com

Good luck!

73
Frank
W3LPL

---- Original message ----
>Date: Fri, 25 Jan 2008 04:43:43 -0800 (PST)
>From: Tom McDermott <tom.mcdermott4 at yahoo.com>  
>Subject: Re: [TowerTalk] About to pull the trigger  
>To: towertalk at contesting.com
>
>> 1. AN Wireless tower, 90', heavy duty, rated at 36 sq.ft
>>   2. M2 40M4LLDD at 90'
>>  3. 2 x KT36XA at 100' and 60'
>>  4. Prosistel PST61D + Green Heron to rotate the 40m beam and the upper tribander
>>  5. K0XG ring rotator + Green Heron for the lower tribander
>>  6. W3NQN bandpass filters sandwitched between 2 SO2R switches to provide SO2R filetring
>>  7. BIP/BOP stack controller for the KT36XA tribanders
>>  8. SO2R switch for all antennas
>>  9. On 80m, Comtek dipole 4sqr as in http://www.comteksystems.com/4square6.html
>>  10. On 160m, shunt feed the 90' tower
>>  11. RX antennas- 2 two-way beverages
>
>
>Built almost this same setup in 1984 using Rohn 45 (different rotators). Comments:
>
>2. I don't know if there have been mechanical improvements in the 4M40 since 1984. Referencing
>the older design: the element clamps on the 4M40 came loose. Use 3 stainless hose clamps.
>The clamps usually have a small hole, drill a matching hole in the boom and pin one clamp of each
>element to the boom with a #6 sheet metal screw.  Most of the linear-loading insulators broke. Replace
>them.
>
>3. The 4M40 at 90' heavily detuned the KT34XA at 102' on 15m. The 34XA was poor on 15m to
>begin with, near the 4M40 it became totally useless. A 15m dipole at 20 feet was 30 dB better, literally.
>I added a gray (UV resistant) PVC dummy element near the front end of the 34XA to balance the wind
>torque, worked great. Rebuilt the 34XA with the rebuild kit in 1996 to fix the 15m problems, but they
>got worse instead. The 36XA may have these issues dealt with, I'd check it carefully before putting it
>up on the tower.  The 34XA at 102' worked great on 20M and 10M. Had a 20' 3" steel mast (210 
>pounds). It was 8' inside the tower and 12' outside the tower. Used a chain hoist to raise and lower
>the mast to get to the top antenna, recommend using a high quality one for positive control. Added a
>second clamping arrangement inside the tower to hold the mast while raising or lowering. It was loose
>when the rotator was in place.
>
>4. First rotator (HDR-300) lasted 14 months, as totally destroyed as a rotator can get. Second rotator
>was an Emotator 1300 and a home-made torque isolator using a BMW transmission-to-drive-shaft
>rubber donut described in the Dave Leeson's Physical Design of Yagi antennas book.
>Good idea, worked great.
>
>5. Did not use the lower antenna much at all, finally removed it. I was not trying to operate SO2R
>however. It did not provide any benefit working the Carribean from North Texas compared to the
>high yagi.
>
>9, 10 Shunt fed the tower on both 80 and 160. Worked well for DX on 80, not as good stateside. Very
>good Tx antenna on 160m. Ended up with a 15kv vacuum variable and stepper motor combo to tune the
>antenna. On 80M it would tune 3.5-4.0, on 160M I added a 4:1 transformer and used the same tap
>point (12.5 ohms on 160 => 50 ohms on 80) it would tune 1.8 to 2.0.  Transmitting variable breadslicer
>style capacitors with 3.5kv rating arced over at 1500 watts.
>
>When I moved a couple of years ago, the neighbors were concerned I might remove the tower. It was home
>to red-tailed hawks, large owls, etc. and most of the neighbors liked the bird watching and did not want to
>see the antennas or towers go. The buyer wanted the towers and antennas, so they remained.
>
>Would I do it again?  You bet.
>
>    -- Tom, N5EG
>
>
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