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## [TowerTalk] Prop pitch motor.

 To: [TowerTalk] Prop pitch motor. "Jim Thomson" "Tower and HF antenna construction topics." Mon, 15 Mar 2010 00:47:07 -0700 mailto:towertalk@contesting.com>
 ```Date: Sun, 14 Mar 2010 22:13:17 -0700 From: jimlux Subject: Re: [TowerTalk] Prop Pitch Motor Gene Fuller wrote: > What is the maximum DC voltage used successfully/recommended for one of the > "small" PPM's ? What speed was accomplished and how was the brush life at > that voltage ? > I 'm building a power supply to put at the base of the tower and can change > the voltage from about 30 to 48 volts in 6 volt steps. Cable to PPM will be > 100 feet of 3-#12's. I'm figuring about 0.5 ohms and about a ten amp demand > i.e. a 5 volt drop. > Any suggestions will be greatly appreciated. > Thanks, > Gene / W2LU Handy to remember.. AWG 10 wire is about 0.1" in diameter and 1 ohm/1000 ft. For every 3 gauges, the resistance doubles. For every 10 gauges, the resistance is x10. So.. 200 ft of AWG 10 (up and back) would be 0.2 ohms. Going to AWG 12 is a bit less than doubling (0.4 ohms) Your estimate of 0.5 ohms for AWG 12 is a bit pessimistic. (assuming a single conductor up and back) If you were thinking triple AWG 12 up and triple AWG 12 back, you'd be much less than 0.2 ohms total, since 3 AWG12s is almost twice the cross sectional area of a single AWG10. ## 3 x 12 ga wire in parallel = 9 ga wire. =.8077 ohms per 1000' ## 200' loop = .16154 ohms. With 10A... V drop = 1.6154 V ## dunno abt DC motor's but start up current on small AC motor's is typ 3 X the running current. I have measured several small ac motor's.. and typ measured 3.1 X the running current. ## I had a small prop pitch motor back in the 70's. It was 1 min, 50 secs to do 360 degs. No load Vdc was aprx 30 vdc. Forget what size wire was used. It was 175' run.. or 350 ' loop. Jim VE7RF _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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