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Reviews Categories | Antenna Rotators & Accessories | Prop pitch rebuilt by K7NV Help


Reviews Summary for Prop pitch rebuilt by K7NV
Prop pitch rebuilt by K7NV Reviews: 6 Average rating: 5.0/5 MSRP: $3000.00
Description: K7NV does a complete rebuild of prop pitch motors, replacing bearings etc.

The service is listed on his website under "The K7NV Notebook"
Product is in production.
More info: http://www.k7nv.com/
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AC8DE Rating: 5/5 Mar 31, 2014 11:35 Send this review to a friend
Better than the Best by Far  Time owned: 6 to 12 months
The Prop Pitch is the “holy grail” of rotators (short of industrial gearboxes), but they have a complex install and only make sense for those that have big heavy arrays… or have plenty of money and simply want the best. The prop pitch is an interesting and unique rotator with unique requirements and unless you've went through the motions of installing one, you don't know how unique it is. Kurt’s remanufacturing work is absolutely immaculate putting this rotator truly in a class all by itself. (It’s called a “rebuild” here on e-ham, but it truly is a remanufacture.) It is a serious piece of hardware for serious hams that have pockets deep enough to spend serious money on their equipment, but has serious install requirements as well.

Their HUGE gear reduction either 7,000:1 (medium or large size) or 9,500:1 (small size) and the fact they were built for military plane propeller pitch control (hence the name) makes them pretty special in many ways. Kurt’s rebuilds are not oil filled like they were originally, but rather grease packed for rotator service. They are true triple-stage planetary gear drives and have stupid high torque capability that puts their safety margin so high that they yawn at turning a large array. But they do turn slower than most other rotators due to the high gear ratio. An interesting fact is that if you adjust for the time value of money for when they quit making the prop pitch in the mid 1950's, if they still made it today, the SMALL unit would cost about $28,000! That gives you an idea of the kind of mil-spec build quality and capability it has, as there was no corner cutting in its design like other rotators.

The normal situation for installing a prop pitch is usually a high dollar large array installation and not just for a typical tribander due to its size and cost. The small prop pitch will fit in smaller towers like a crank up. (The smallest version of a prop pitch is larger than a Tailtwister, so it won't fit in compact crank-ups.) The medium size won't fit in anything smaller than Rohn 45. Even then you have to either cut out a cross brace or drop it in from the top, as it is physically long with the big motor on the bottom. And they are HEAVY! When I took delivery of the medium sized one from K7NV I was shocked at the weight when I tried to pick up the big tube it came in, as I hadn't considered how much it weighed. Packed, it weighed about 80 lb. Just the heavy mounting plate made to take the appropriate vertical loading and a heavy duty top bearing plate for the appropriate sized thrust bearing will set you back $500, not including the thrust bearing! If you add an intermediate plate, even more money is needed. It sure ain't no Ham IV installation! hi hi

The prop pitch requires higher amperage than other large standard rotators, so not just any controller can be used. A special Green Heron RT-21pp is what is normally used and is what Kurt supplies with a rebuilt unit. I hadn't considered the high current required by a prop pitch with a 280' wire run and how that affected voltage drop and wire gauge. The minimum wire I could go with was 10 gauge, which causes a 10% voltage drop at nominal current draw of 5 amps. At the peak amps of 8, it hits 17%, but I expect that we will never see that because we will keep the ramp rate pretty low. Jumping up to 8 gauge nearly triples the wire cost and does get the drop down to 10% drop at 8 amp peak current draw, but at nominal current draw it’s only a 3-4% difference, which isn't enough in speed/torque to worry about. A prop pitch requires 3 parallel runs of the heavy gauge wire and 2 conductors of small size for the feedback.

While not really a “negative”, if there is one thing I don’t like is that it still utilizes a terminal strip for electrical connection. A nitpick, I know. I’m sure this is to keep the connection universal and to follow the practices of most other rotators, but is a throwback to days gone by in my mind and doesn’t really suit this rotator with the connector options available today. I’d rather mount a weather proof Deutsch connector on it so that all connections are hermetically sealed from the elements without any goop and I don’t have to worry about a terminal screw coming loose. But that is just my preference and not really a negative.

If you can afford or need a K7NV rebuilt prop pitch, you’ll NOT be disappointed.
 
K8GTQ Rating: 5/5 Nov 13, 2012 11:21 Send this review to a friend
great rotor-built like a battleship  Time owned: 3 to 6 months
I have a SteppIr monstir. With a S/S tilt plate and antenna there is nearly 300 lbs on the rotor. A M2 2800 was NOT up to the job. I replaced it with the smaller prop pitch rotor from, K7NV. The rotor operates smoothly, quickly and flawlessly with the green heron control box. Absolutely no wiggle or turn in the highest winds. installation and setup is a breeze. Should last me the rest of my life!
Good Job Kurt!!
K8GTQ, richard
 
KG4LRU Rating: 5/5 Apr 1, 2012 22:14 Send this review to a friend
Rock solid  Time owned: more than 12 months
Kevin rebuilt my prop pitch 4 years ago ,it was original Tri EX prop pitch . I was able to do away with all the mechinical stops , Set-up was easy I also purchased his Rotor box its built by Green Heron . Its turns two antenna 100 ft skyneedle . I cant say enough good thing about the rotor . When it came back it looked like a work art. I had some major wind and Ice . Make no mistake these prop pitch will out last me . K Rumor has it Kevin has never had a failure of one of his prop pitch rebuilds .
 
WD8NPL Rating: 5/5 Jan 6, 2011 19:18 Send this review to a friend
Great Job!  Time owned: more than 12 months
I had Kurt rebuild a small prop pitch unit a couple years ago for me. He did a great job and the unit has preformed flawlessly ever since. I wish I couls say the same about the M2 RC2800PX controllers that do not work but that problem was solved today when I ordered a K7NV/Green Heron Prop Pitch controller. I am sure it will perform flawlessly as Kurts' rebuilt prop pitch units do.
 
N6KD Rating: 5/5 Jun 30, 2009 17:00 Send this review to a friend
Great refurbishing  Time owned: more than 12 months
I had Kurt overhaul two old prop pitch rotors and to add Mast to rotor connections. Kurt does an outstanding job - he really understands these rotors and how to make them into very good, reliable units. I still use my old M2 controllers and the combination is great.
 
K1XM Rating: 5/5 Apr 10, 2006 19:03 Send this review to a friend
Like a new rotor  Time owned: 0 to 3 months
Kurt does a complete rebuild of a prop pitch motor, stripping it, replacing or rebuilding bearings, sandblasting and painting the case, building a new top seal etc.

The result is essentially a new prop pitch, only better because it is set up for use as an antenna rotor.

It is a fine replacement for my old prop pitch which has been up for 20 years.
 


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