[TowerTalk] Prop Pitch operating characteristics

Tue Mar 19 11:38:44 EDT 2024

As fate would have it, about 10 days ago I noticed a sub-folder on my web server named /k7nv.com and figured nobody was interested any longer so I deleted it, but here it is mentioned in this group once again. I seem to recall a long time ago I downloaded the entire website because it was going to go away and somebody was asking to preserve it.

I've restored it from a backup in case anybody is interested. http://www.hamoperator.org/k7nv.com/

If anybody is interested in hosting these files please let me know and I'll send you a link to a zip file of the whole site. There might come a time again when I forget what this is and delete it once more.

73 
Danny, K5CG 
HH 550-000-0609 
SKCC 14257

----- Original Message -----
From: "Bob via TowerTalk" <towertalk at contesting.com>
To: leeson at earthlink.net, "towertalk" <towertalk at contesting.com>
Cc: npalex at bellsouth.net
Sent: Monday, March 18, 2024 10:02:06 PM
Subject: Re: [TowerTalk] Prop Pitch operating characteristics

Looks like Dave came up with the info on the PP units. I found my file which contains a lot of what Kurt had copyrighted in 2005 and includes adapter plates, small, medium and some info on the large and extra large motors. What I have is a small, a large and two extra large PP motors which according to Kurt would be good for turning the whole tower. In the late 50's I used the small one on top of a power pole with a homemade gear driving a selsyn for direction indication. 
73Bob K6OSM 
In a message dated 3/18/2024 4:58:59 PM Pacific Standard Time, leeson at earthlink.net writes: 
For a start, see 
https://web.archive.org/web/20200711193004/https://k7nv.com/notebook/ppinfo/

See also 
https://ve3vn.blogspot.com/2015/11/choices-on-adapting-prop-pitch-motors.html: 
"On a bench test one drew 8 A and the other drew 7 A at 24 VDC."

An interesting idea for using series resistors to reduce startup surge 
is at http://www.bigskyspaces.com/w7gj/NewMotor.htm

See also https://www.eham.net/reviews/view-product?id=5837 comments by 
AC8DE: "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."

Because my towers are some 400 feet from the shack, I built a remote 
power setup at the tower with a transformer 24 volt supply and relays. 
Because the motor is a DC type, the relays are wired to present a short 
when not rotating, which acts as a brake. Kurt made me a special mast 
connector with a rubber torque isolator (I have blueprints), which has 
worked brilliantly in our storms with gusts over 120 mi/h. I run Romex 
cable from the supply to the rotator.

See also 
https://www.greenheronengineering.com/product/rotator-controller-prop-pitch/
https://www.greenheronengineering.com/product/prop-pitch-28vdc-motor-rpu/
http://www.zs6p.com/PPM_gearbox-sketches_and_notes.pdf

If I have more info, I'll dig it out and provide it. I had a physical 
copy of the Section 12, Curtiss Wright 1943 Hollow Steel Blade Propeller 
(3 Blade) Service Manual that I shared with Kurt K7NV, but I don't have 
a scan. See 
https://app.aircorpslibrary.com/document/viewer/11a5e262-f115-4949-bbe5-8d3ab3803e59 
and https://www.ebay.com/itm/275383055212

73 de Dave, W6NL/HC8L

On 3/17/24 6:40 PM, Bob via TowerTalk wrote:
> Hi Norm,
> This is Bob Schaefer K6OSM and I used a PP motor on a Hornet tri-band beam back in the late 50's. I will look in my files to see what I can find on these motors. I do recall that the elapsed time for a complete turn was close to a full minute. I live in Gardnerville and Kurt lived in the adjoining town of Minden, I never made personal contact with Kurt but exchanged info with him when I lived in Idaho. I still have four PP motors and will see if I can find anything that will help you.Bob K6OSM
> In a message dated 3/16/2024 10:29:49 PM Pacific Standard Time, npalex at bellsouth.net writes:
> Hopefully there are some TowerTalk participants that are using PropPitch rotor systems.  I am looking for some operating characteristics relating to supply voltage, currents and rotation speed (time to do 360*).  I have been a prop pitch user for many years and my 'go to' in the past on such questions would be Kurt K7NV now SK or Joel K2QVB also a SK. My prop pitch dates back to W0MLY Dick Mckercher, DXer of the 50's and 60' and creator of Antenna Mart products.  That is the background - Specifically I am look for the DC voltage at the 'controller' and the voltage underload at the PP motor.  What is the 'start-up' surge current and the steady state 'run' current.  Those using Kurt's Green Heron controller, results may be different as it supplies is PWM ramp up and down, but the 'run' levels will be "DC" and useful data.  Finally is there anyone who has the working knowledge of Prop Pitch assemblies, or maybe have access to the information that Kurt accumulated the could be made available us PropPitch users?Looking for some help --Norm W4QN |  | Virus-free.www.avast.com | _______________________________________________   _______________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk
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