Gene,
I have never had to replace the brushes on mine. Each time I serviced it, I
chucked the rotor shaft in a drill press and cleaned the commutator with
emery cloth. Then I cleaned each slot with a dental tool to get all the
brass filings out so they would not short together. It has never been
machine turned.
I anticipated the aging factor or the PPM and myself when I installed the
tower at this QTH. I'm 76 and have had both knees replaced. Climbing is now
out of the question. Hence the ground level installation.
I have the rotor transformer and antenna switching relays mounted in a box
adjacent to the rotor assembly. I only have about 3 ft of wire from the
transformer to the rotor motor. I installed two phenolic snubbers around the
mast between the rotor and the top of the tower to minimize whiplash. The
motor shaft seal started leaking, so I installed a automotive grease zerk on
the side of the gear box, and give it a lube job periodically. The light
weight grease does not leak thru the motor seal. I did drill a small hole in
the motor cover early on.
My coax and control cables run underground in PVC pipes and come up in the
wall behind my operating desk.
73's Jim - W5IFP
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of Gene Fuller
> Sent: Monday, April 12, 2010 9:04 AM
> To: Tower and HF antenna construction topics.
> Subject: Re: [TowerTalk] Fw: Prop Pitch Motor Power Supply
>
>
> Thanks Jim, it sounds like you have a really nice setup. I've
> gotten to the
> point where I should be looking at something more like that. I have moved
> the power supply to the base of the tower, but a 100 foot pipe mast still
> seems a bit daunting. There would still be te problem of the big LP up on
> top. I wasn't looking far enough ahead when I designed my system.
> e.g. the
> ppm is mounted on the top side of it's mounting platethus making
> it almost
> impossible to change it out without bringing the whole carriage assembly
> down.
>
> I'm beginning to wish I had left my system on AC. Have you ever replaced
> the brushes and/or had the commutator turned down? I didn't know
> any better
> than to fill the gat case with oil wo there's the possibility
> that the lower
> seal finally gave up and the rushes/commutator are all burned up from oil
> seepage. Someone did suggest to me that I drill a hole in the
> bottom of the
> motor can to drain any oil that made it that far. Fortunately I have an
> extra motor. Now if I could just find/teach someone who could climb the
> tower and replace the motor (and a few other little odds and
> ends). In the
> meantime I have a TH-6 on a side gate a 45 feet that does supprising well.
>
> 73's,
>
> Gene / W2LU
>
> ----- Original Message -----
> From: "Jim Hargrave" <w5ifp@gvtc.com>
> To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
> Sent: Monday, April 12, 2010 9:13 AM
> Subject: Re: [TowerTalk] Fw: Prop Pitch Motor Power Supply
>
>
> > Gene,
> >
> > I'm no expert on motors, but will offer my experience.
> >
> > The prop pitch motor is a AC/DC type motor, however it was
> designed to run
> > on 28 VDC.
> >
> > I have used a small Prop Pitch motor since the 1960's and have
> always run
> > it
> > on AC. I use a 24 volt battery charger transformer with a
> variac on the AC
> > power side. I use light weight lithium chassis grease in the
> gearbox, so
> > it
> > slows down a little when the temp is below freezing. I make minor
> > adjustments of the variac to maintain a reasonable speed between
> > summer/winter operation.
> >
> > The first twenty years I had it rotating a homebrew three element
> > tri-bander. Since that time it has rotated a HyGain TH6
> Tri-bander and a
> > 14
> > element 2M beam. I have had it at three QTH over the years and
> I serviced
> > the unit each time I moved. It has been operational for 13
> years at this
> > QTH
> > and has not needed servicing (yet--knock knock). You can minimize brush
> > arcing and prolong the life by making sure you clean out the spaces
> > between
> > armature contacts.
> >
> > I mounted the rotor at the top of the tower at the two previous
> QTH, but
> > now
> > have it mounted about 4 ft of the ground and run a mast up the
> tower. Its
> > a
> > 50 ft tower and the mast is galvanized water pipe with a section of
> > schedule
> > 40 at the top where it goes thru the tower top section. I have
> a section
> > of
> > automotive driveshaft at the bottom including the u-joint, so shaft
> > alignment is not a problem. The whole assembly is quiet heavy
> and is cable
> > suspended so there is no weight load on the rotor gearbox.
> >
> > 73's Jim - W5IFP
> >
> >
> >> -----Original Message-----
> >> From: towertalk-bounces@contesting.com
> >> [mailto:towertalk-bounces@contesting.com]On Behalf Of Gene Fuller
> >> Sent: Monday, April 12, 2010 12:18 AM
> >> To: towertalk@contesting.com
> >> Subject: [TowerTalk] Fw: Prop Pitch Motor Power Supply
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: Gene Fuller
> >> To: tips@contesting.com
> >> Sent: Monday, April 12, 2010 12:48 AM
> >> Subject: Prop Pitch Motor Power Supply
> >>
> >>
> >> AC or DC is the question. I have heard from several sources that
> >> the PPM's should be run from DC or else the brushes would not
> >> last as long as they might. I had run one for 30-40 years on AC,
> >> with small to medium sized antennas, befor any sign s of a
> >> problem. In view of the recommendatioins I added a diode bridge
> >> to give me some DC. At the same time I had the commutator turned
> >> and put in new brushes. Much to my dissapointment it now appears
> >> that after only 6 or 7 years (turning a fairly large, 7-60 MHz)
> >> LP) at least the brushes are gone. Over a period of a few days
> >> the speed dropped to about 0.1 RPM and finally quit all together
> >> (same CW or CCW). I haven't had a chance to get the motor down
> >> off the tower yet.
> >>
> >> I was recently talking with an acquaintance who is an engineer
> >> and seems to be familiar with electric motors and he was quite
> >> emphatic that AC would generally be preferable. The reason is
> >> that with DC you tend to draw an arc from sector to sector of the
> >> commutator as the armateur rotates, whereas with AC the arc tends
> >> to be self-extingushing as the wave passes through zero. I didn't
> >> think to mention to him that the motor operates at about 9,000
> >> RPM. Perhaps he is right with motors that operate at lower speed
> >> relative to 60 Hz, but with the PPM running such high RPM's and
> >> drawing less current when operating on DC, DC really is the right
> >> way to go.
> >>
> >> Any comments would be appreciated.
> >>
> >> Gene's / W2LU
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|