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Re: [TowerTalk] FW: UST Tower MA770 Starting Motor Capacitor

To: towertalk@contesting.com
Subject: Re: [TowerTalk] FW: UST Tower MA770 Starting Motor Capacitor
From: Leeson <leeson@earthlink.net>
Reply-to: leeson@earthlink.net
Date: Wed, 31 Jan 2024 21:22:08 -0800
List-post: <mailto:towertalk@contesting.com>
A safety point: A good motor cap can hold the instantaneous value of the alternating voltage at the moment of disconnect. It's good to short it before touching the terminals. I use a jumper, and the zap and arc at times is quite surprising.

Dave, W6NL/HC8L

On 1/31/24 1:31 AM, maflukey@gmail.com wrote:
Starting caps come in value ranges. My experience is that slightly higher
values generally pose no issue, whereas too small may not be enough to get
the motor started under load.    Try it to confirm.   If motor stalls on
startup, stop and go to a larger cap.

Hope this helps and good luck on your project.

73
Matt
KM5VI



-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Joe Subich,
W4TV
Sent: Tuesday, January 30, 2024 7:52 PM
To: Raymond Benny <rayn6vr@gmail.com>; [TowerTalk]
<towertalk@contesting.com>
Subject: Re: [TowerTalk] UST Tower MA770 Starting Motor Capacitor



  > How rigid is the 375MFD value?

Not that rigid ...

I have found on eBay a cap, 378-454 uF MFD at 250VAC. Would this meet
the starting cap value?
Easily.

73,

     ... Joe, W4TV

On 1/30/2024 8:39 PM, Raymond Benny wrote:
   I've had a MA770 tubular tower in the air for the last 15 years. I
got it second hand 20 years ago. It's probably 40 years old. I need to
replace the raising motor starting cap.I have the old cap in my hand
and all I can read is 375 MFD. The motor operates on 120VAC. The motor
name/data plate has been painted over, so I cannot read anything about
it

I have several questions:
Does anyone have the make, model number or manufacturer info for MA770
motor? And the info on the starting cap?

How rigid is the 375MFD value? I have found on eBay a cap, 378-454 uF
MFD at 250VAC. Would this meet the starting cap value? I know I don't
need 240 VAC rated, but one rating should not be a problem. The
measurements given for the cap will fit into the external cap holder.

Thanks,
Ray,
N6VR/W7YA




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