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Re: [TowerTalk] Prop Pitch operating characteristics

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Prop Pitch operating characteristics
From: Danny K5CG <k5cg@hamoperator.org>
Date: Tue, 19 Mar 2024 08:38:44 -0700 (PDT)
List-post: <mailto:towertalk@contesting.com>
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@contesting.com>
To: leeson@earthlink.net, "towertalk" <towertalk@contesting.com>
Cc: npalex@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@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@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 |  | 
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