[TowerTalk] Problems with YAESU Rotor
Mike Holley
mholley@quik.com
Mon, 15 Feb 1999 19:37:29 -0800
Thank you Richard and all others that responded to my request for input on in
service reports on YAESU 800 series of rotors .
The one important factor I seem to have derived from all the data is that I
should have allowed all or part of the (HAM-PRO) antenna (20 mtr 4 element full
size)
For those that may be unfamiliar with the "HAM-PRO" series of antennas, I saw
them first being domesticated at the ARRL PNW convention in Sea Side OR in 1992
.The company had some 30 years of commercial TV and FM Broadcasting antenna
experience and decided to expand the high degree of expertise in the Amateur
Radio Antenna field.
They produces only mono band full size antennas for 3/4 mtr down to 20 mtrs.
The one very unique feature about the there design was a new type of driven
element feed method which they called a "Double Gamma Feed System" which in
reality produced a relative very low SWR over the entire band without the aid of
any external antenna matchers . Also the unbalanced feed point was terminated
in a "N" connector at the centre of the boom directly above the pipe clamp.
The mechanical Specs of this antenna are:-
Boom length
.........................................................................33.58
ft
Boom OD .....................................................................
2.5 X .083.
Tapered elements section dia.......................................
.1.25/11.0/.75/.50
Tensile strength boom, elements extrusions ............... 45ksi
Turning Radius
..............................................................24.4 ft
Wind survival with 1.4inch of ice coating .......................87 mph
Wind ,max. gusts without ice coating 112 mph
Total wind catch area at max. wind pressure direction 8.27 sq ft
Wind load at EIA 87 MPH wind velocity ,worst wind 248lbs
Net weight completely assembled antenna 69 lbs
-------------------------------------------------------------------------------------------
I should point out that this antenna (The only one attached to the G-800SDX was
mounted directly above the thrust bearing which was 6 feet above the rotor which
in turn was mounted on a plate inside the tower.
Several comments were made in respect to the way I installed the rotor
relating to the antenna downward weight distribution . Thinking it would be best
to relive the rotor of much downward weight as possible (About 80lbs) All the
weight was placed on the thrust bearing (A commercial grade ball race bearing )
This means that the rotor had no downward weight at all even though YAESU specs
for the G-800 indicates good to 450lbs . I t was explained by several
contributors to "Towertalk ' that this could have caused the destruction of the
rotor due to excessive fishtailing action during high winds in addition could
also account for the two failures on the control indicator motor and the carbon
film resistor . I did in fact register a very small amount of fluctuating
indication +/- maybe 1deg but could hear the indicator motor starting and
stopping while trying provide a new indicated setting .
What ever rotor I replace the destroyed G-800 I think it would be wise to allow
the antenna weight to rest entirely on the rotor (Comments please)
One comment I would like to pass on in respect to after sales support on the
YAESU rotor that I had . First I tried to get repair service from the local
YAESU authorized dealer and was advised they did NOT service any of the Yaesu
rotors and suggested that I deal directly with Yaesu in California.
My next approach was to try and get a full shop manual for the rotor (Not just
the operators /Installation manual that came with the G-800 . I am quite aware
that schematics are provided but if you have ever had to open the controller you
will see that with out a pictorial component layout it is very difficult to
trouble shoot .
This resulted in me having to return the controller to Yaesu repair department
on two separate occasions to have the same repair ie the indicator motor and one
carbon resistor replaced at a cost of over $80.00US plus S&H .Although the
repair invoice catalogued the defective components (And returned them) No
indication as to the cause of the failure was given .
With respect to the rotor proper (G-8000) as mentioned before with the
exception of the upper and lower outer housing, the ball bearings and the 24dc
motor all gears ,limit switches and a potentiometer were destroyed almost beyond
recognition.
The internal assembly consisting of the gear train ,limit switches etc. very
obviously are bench assembled prior to being installed in the lower housing .
What I wanted to purchase was just that ,but Yaesu repair department advises
that such an assembly is NOT available only a replacement G-800 rotor at
$329.00US plus S&H .
For those out there that have had no problems with the YAESU rotors I respect
your comments and appreciate why you like the features in particular the450 deg
rotation and the pre-set function ,but, if you ever do have to get repairs done
I hope you get better dealer support than I did .
Thank you Richard and all that came to my
request for help
Mike Holley VE7AVM
Richard Thorne wrote:
> Mike:
>
> Just a quick note on the Yaesu's and square footage ratings. They really
> don't tell you a lot.
>
> They use a a K-Factor to determine load. The K Factor is the turning radius
> of the antenna multiplied by its weight. The K Factor rating of the G-800
> is 1299 ft-lbs. Not sure what the dimensions or weight is of the ham pro
> but go through that calculation. The K Factor is more important than the
> square footage of the antenna.
>
> I have a G1000SDX and its currently turning a 30' boom C4XL. The rotor is
> doing a good job.
>
> Mike Holley wrote:
>
> > Hello ,
> > My Name is Mike and I am looking for reliability data from
> > present and past users of YAESU Antenna rotors ,in particular the
> > G-800SDX model .
> > I have had one in service for the last five years during which I have
> > had two failures of the control unit and the most recent (This month
> > Feb.) of a total destruction of the rotator unit due to gusts of high
> > winds (50/60 mph)
> > A brief history of the Yaesu G-800SDX
> > Purchased in 1994
> > Installed in a 70 ft Self supporting tapered tower on a rotor platform
> > 6ft below to top of the tower ,
> > The antenna (One only) is a 4 element 20 mtr monoband (HAM-PRO) which
> > has a published wind surface area of 8.4 sq.ft. (well below the maximum
> > capacity of the Yaesu rotor specs of 15 sq.ft) .The antenna was attached
> > to the rotor with a 2 inch schedule 40 seamless aluminium heavy wall
> > pipe (10')and weight supported by a commercial grade ball race thrust
> > bearing which was installed to absorb all the vertical weight of the
> > antenna .
> > weight and balance was addressed at all times during the installation .
> > FAILURE No. 1
> > In 1995 (Less than one year after installation the controller failed to
> > operate and because of it's complexity (Electronic/Electrical) and No
> > Service manual obtainable ) had to be returned to YAESU repair
> > department in California .
> > A small DC motor and one carbon resistor were found defective and
> > replaced
> > at a cost of $80.33 Plus S&H
> > Failure No. 2
> > In 1998 the same two components failed again and had to be replaced at
> > a further cost of $81.40 Plus S&H
> > FAILURE No.3
> > IN 1999 within the last two weeks (Jan.Feb) it was noticed that the
> > antenna was wind milling during relative high wind gusts ,it was also
> > observed that the co-ax feed line had broken away from the feed point on
> > the antenna .
> > When the rotator was brought down an opened it was discovered that the
> > total electro/mechanical assembly with the one exception the small DC
> > drive motor was completely destroyed beyond any possibility of repair .
> > The only salvageable parts were ,the upper and lower housing and the
> > ball bearing races .
> > With an e mail to YAESU with a brief history of what had taken place
> > and to enquire if a complete internal sub assembly was available or do
> > I have to purchase a whole new rotator minus the controller . The reply
> > was that complete sub assemblies were not available but that a
> > replacement Rotor less the controller was .
> >
> > A decision I have to make now is to I replace the Rotor or install
> > another brand of rotor . which will entail a lot of tower work .
> > I would be most interested to hear from any other YAESU G-800SDX users
> > that has experienced any form of problems as this will help me decide on
> > the next route to take .
> > Thank you one and all for taking the time to read this .
> > Respectfully
> > Michael Holley VE7AVM
> > e mail address <mholley@quik.com>
> > 73 - Michael, VE7AVM @ VE7KIT
> >
> > Message timed: 11:28 on 11 Feb 99
> > Message sent using WinPack V6.4
> >
> > --
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>
> --
> 73,
> Richard Thorne - N5ZC (Ex. KA2DSY, N2BHP, WB5M)
> Amarillo, TX
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