Dick,
The problem doesn't have anything to do with freezing or being against the
stop. It never freezes here and I see the problem all the time. The problem
is bigger if it is against the stop because you can't rock it back and
forth. I imagine that your cold weather could certainly add another element
to the problem though.
Bill, W5VX
>-----Original Message-----
>From: towertalk-bounces@contesting.com [mailto:towertalk-
>bounces@contesting.com] On Behalf Of Dick Green WC1M
>Sent: Monday, February 12, 2007 10:18 AM
>To: 'W2RU - Bud Hippisley'; towertalk@contesting.com
>Subject: Re: [TowerTalk] Ham IV
>
>Nothing new about that feature. The Hy-Gain DCU-1 controller has it, as
>does
>the Idiom Press upgrade for the stock Hy-Gain controller. It's not really a
>rocking motion. Whenever you move to a preset, the controller attempts to
>turn the rotor a few degrees in the opposite direction, then proceeds with
>moving to the selected target.
>
>Hy-Gain (before MFJ bought the company) was well aware of the sticking
>problem, but was unable to fix it. I think part of the problem is that
>there's more than one failure mode. One is definitely temperature-related.
>We here in the frigid Northeast often experience a "stuck" Tailtwister or
>Ham IV when the temperature gets below freezing. It can happen anywhere the
>rotor happens to be parked. The other mode seems to be independent of
>temperature and happens when the rotor is run against a stop. Rocking back
>and forth can free the rotor in both cases.
>
>I don't know much about the second failure mode -- it's never happened on
>the two Tailtwisters and two Ham IVs I have in my system. Then again, I
>don't run the rotors against the stops very often.
>
>I experienced the low-temperature problem frequently on a Tailtwister that
>I
>no longer have, and have sometimes seen it on my two Ham IVs. It's never
>happened on the two Tailtwisters I have now (knock on wood.) When I had the
>bad Tailtwister, it would get stuck virtually every time the temperature
>dropped below 32 degrees. Most of the time, rocking back and forth freed
>the
>rotor, but not always.
>
>Hy-Gain was well aware of the temperature problem. They told me some rotors
>had it and some did not, and they had so far been unable to determine the
>cause of the problem. They, and many hams, have tried repacking the
>bearings
>with low temperature grease, but there have been mixed results. Hy-Gain
>felt
>that the brake wedge was getting stuck, and that this was caused by the
>shape and spacing of the teeth, and was also influenced by the size of the
>load. They had a new design for the brake wedge, but didn't have a test
>setup in which they could conveniently test the rotor under load at low
>temperature. Since my Tailtwister was mounted at the bottom of a rotating
>tubular tower, and we frequently have cold temperatures, I offered to help
>them. They sent me a brand new Tailtwister with the old brake wedge, and I
>sent mine to them. They fitted my Tailtwister with the new brake wedge and
>sent it back. Unfortunately, the new brake wedge did not fix the problem at
>all -- the symptoms remained exactly the same.
>
>But while Hy-Gain was "upgrading" my rotor, I discovered that the
>Tailtwister they sent me did *not* have the problem. When the new wedge
>test
>failed, Hy-Gain agreed to let me keep that rotor and I sent the bad one
>back
>to them. I think that was at least 7 years ago, and the Tailtwister has not
>frozen up even once since then (knock on wood.) Sometimes the Ham IVs are
>reluctant to start when the temperature is well below zero, but a few
>pushes
>of the preset button (i.e., rocking back and forth) has always freed them.
>Since the cable runs are very long to those two rotors, I doubled the gauge
>of the brake and ground leads to reduce the voltage drop. This seems to
>have
>reduced the frequency. I bought a refurbished Tailtwister from Norm's Rotor
>Service about 3 years ago and it has never frozen (again, knock on wood!)
>
>After the revised brake wedge failed, Hy-Gain speculated that the problem
>might have something to do with the "clutch". I'm not familiar with the
>insides of these rotors, but apparently there's a pair of friction plates
>and one of them has a surface made of cork. As I recall, Hy-Gain thought
>moisture on the cork might freeze at low temperature and prevent the plates
>from pulling apart. Never looked into this possibility.
>
>Hy-Gain rotors are OK, but I'm not wild about the brake wedge design. If
>either of my Tailtwisters ever develops chronic freezing problems, I'll
>replace them with a worm-gear rotor -- probably the big Yaesu.
>
>That's probably more than you all want to know about this...
>
>73, Dick WC1M
>
>> -----Original Message-----
>> From: W2RU - Bud Hippisley [mailto:W2RU@frontiernet.net]
>> Sent: Sunday, February 11, 2007 10:29 PM
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] Ham IV
>>
>> Bill Parry wrote:
>>
>> >Usually just rocking the rotator back and forth does the
>> trick. I have
>> >had the problem on my Ham-M rotators many times and this
>> trick always
>> >works for me....I haven't ever seen a rotator of this variety that
>> >didn't do this to some extent. Very common.
>> >
>> >
>> The Green Heron controller has a special Tailtwister "mode"
>> with this rocking motion automatically built in for just such
>> situations. In fact, one of *my* Tailtwisters was the
>> inspiration for the mode -- it has suffered from wedge
>> lock-up for years and years.
>>
>> Bud, W2RU
>>
>>
>
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