On Sat, 29 Jan 2005 20:36:13 -0600,
wrote:

I bought a house out in the boonies and I can only get tv from the
antenna, unless I spend a fortune on satellite. I dont watch it much
so the antenna is fine. The antenna has an Alliance Tenna Rotor on
the pole, but the control box is gone. I'd like to build a simple
control. I was told the motor needs 24volts, but is it AC or DC, and
how do I reverse it?. I know I wont have the pointer, so I will have
to go outside to see which way it is pointing, but as long as I can
move it. Does anyone have a schematic for this, and also know what
numbered wire screws do what on the rotor?

The other option is to buy a used control and there are some on Ebay.
The only problem is how do I know which one will work with my rotor.
Obviously it would have to be an Alliance brand, but beyond that, are
they all the same (other than appearance), or do I need a certain one
to match my rotor?

Thanks to all

The Other George (NOT Bush)


Mine is not for sale on eBay, but I have a control box that I used
with my rotor (which is now lost).

The control box says: Alliance Tenna Rotor. Model U-100, I just
tested it and it works. It has four wires at the bottom. It has
been modified so it rotates across the north and has to be reversed
from the south, in other words, you can swing past north going between
east and west, but if you go to the south, it stops at south and has
to go all the way around to get back to the south. It was an easy
change, but I had to constantly swing between north east and north
west.

write me at my call at towncorp dot net.


--
Buck
N4PGW

wrote in message
...

The antenna has an Alliance Tenna Rotor on the pole, but the
control box is gone. I'd like to build a simple control. I
was told the motor needs 24volts, but is it AC or DC, and
how do I reverse it?. I know I wont have the pointer, so I
will have to go outside to see which way it is pointing, but
as long as I can move it. Does anyone have a schematic for
this, and also know what numbered wire screws do what on the
rotor?

Alliance made several models of rotors differing in their
mechanism for indicating direction. However, the motor
requirements are virtually identical. You will find two motor
windings with a common connection. The motor is powered with
24 volts 60 Hz but in TWO PHASES. The second phase is supplied
by placing a non-polar electrolytic capacitor in series with
the transformer output. Using a center-off single-pole double-
throw switch, you can control the rotor direction.

Connect the common connection of the two motor windings to one
transformer lead. Connect each of the two winding leads to the
switch connections. Connect the switch common to the other
transformer lead. Then connect a 100 uF to 200 uF 50-volt non-
polar electrolytic capacitor between the switch connections.
[If you cannot find a non-polar electrolytic of the correct
value, two conventional electrolytic capacitors with their
cathodes (negative leads) connected together will work, using
the two anode (positive) leads as the non-polar capacitor.]

In the "off" position, obviously the rotor will not turn. In
either of the "on" positions, the transformer voltage will be
directly connected to one motor winding and the other motor
winding will be connected in series with the capacitor to the
transformer voltage. One position will provide clockwise
rotation and the other will provide counter-clockwise rotation.

This will turn the antenna. It's crude, but it works. You
will need to know which model of rotor you have to develop an
indicator circuit if you wish to go further.

73, Barry WA4VZQ

wrote:
The other option is to buy a used control and there are some on Ebay.
The only problem is how do I know which one will work with my rotor.
Obviously it would have to be an Alliance brand, but beyond that, are
they all the same (other than appearance), or do I need a certain one
to match my rotor?

Thanks to all

If you email me I can send you the service manual pages for the U98
rotor. You probably have a U100 and this should help you out.

73
Richard WB8KRN

Regarding position sensing: not that simple! The controller decides
(mechanically) when rotation is complete. When you move the knob on the
controller, one part of the dial is under spring tension and a solenoid that
is controlled by a contact in the rotor itself allows the dial tension to be
released one "notch" at a time. When the two parts of the dial again line
up (meaning rotor is now in the direction you pointed), power to the rotor
is turned off. I suggest you try to find an old control box, and make sure
that the dial spring is not broken.

73, K8AC


wrote in message
news
Hi Barry

Thanks for the info. I had originally thought there was a DC and it
was reversed by polarity. This is a more unusual setup, at least from
what I am familiar with. I find it hard to figure out how that
capacitor causes the reversal, but as long as it works. If I am
correct, this tells me that one wire is forward, on reverse and one
common (ground). That leaves the 4th. Let me guess, that one
controls the indicator position, and I would guess thru some sort of
resistance variation ???? The rest and what you explained makes
sense.

I recall trying to find some of those non-polarized caps for a speaker
crossover setup. Not easy to find. I never know about using two
standard caps in that manner.

PS. How would I determine which is the common wire? I would assume
the other two dont matter, it either turns one way or the other. The
4th, I am not sure how that one would be determined.
George

George,
wrote in message
news

Thanks for the info. I had originally thought there was a DC and it
was reversed by polarity. This is a more unusual setup, at least from
what I am familiar with. I find it hard to figure out how that
capacitor causes the reversal, but as long as it works. If I am
correct, this tells me that one wire is forward, on reverse and one
common (ground). That leaves the 4th. Let me guess, that one
controls the indicator position, and I would guess thru some sort of
resistance variation ???? The rest and what you explained makes
sense.

The capacitor, in series with one winding changes the AC phase
of the applied winding voltage. Remember I said it was a two-
phase motor.

The indicator function is not always that simple. Alliance
made one rotor where the control box had its own synchronous
motor that turned the same speed as the rotor. You turned the
knob to the desired azimuth which closed the internal switch.
The switch was opened when the position of the motor in the
control box matched the azimuth setting. However, occasionally
the two motors would get out of sync with each other. Turning
the knob to first one end of its range, letting the internal
motor stop, and then turning the knob to the other end of its
range and waiting for the internal motor to stop would
synchronize the two. This worked by having one of the two
motors reach its mechanical stop while the other still turned.

Another version used a rheostat winding in the rotor unit that
supplied a meter in the control box. This is a special AC
meter and one which is not easy to duplicate. Yet another
version used a switch inside the rotor that was attached to a
gear such that the switch was momentarily closed every few
degrees. In the control box, there was a solenoid that pulled
a ratchet that drove the indicator mechanism. The indictor
jumped in rather coarse steps and clicked loudly.

Probably the most modern system Alliance made used a five-wire
cable. The rotor had a much higher resistance internal
potentiometer than the older models. It was fed from DC and
drove a null-balance circuit. The control box had a matching
potentiometer, and the motor direction and the starting and
stopping was controlled by whether the resistances matched each
other.

I recall trying to find some of those non-polarized caps for a speaker
crossover setup. Not easy to find. I never know about using two
standard caps in that manner.

Non-polar electrolytics are two aluminum foil sheets coated
with the anodic oxide film wound together with a small moist
separator in between. Unlike conventional electrolytic
capacitors, they cannot be reformed and they do not heal.
Hooking two conventional electrolytics like I suggested forms
the same capacitor but it is physically larger.

Send me your email address and I will send you two articles on
electrolytic capacitors you might find useful. Take out the NO
SPAM in the address below to email me.

PS. How would I determine which is the common wire? I would assume
the other two don't matter, it either turns one way or the other. The
4th, I am not sure how that one would be determined.

Get out the venerable old ohmmeter. The motor windings have a
moderate resistance, although I don't remember the value (and
very old Alliance units used much finer wire too). You should
find approximately the same resistance from one wire to two
other ones. This is the common connection. To verify, the
resistance between these two other wires should be double this
resistance. Between common and the indicator wire, you may
measure anything from a few ohms to an open circuit depending on
which model is installed.

Back in the 1960's, the ARRL did some tests on antenna rotors.
When installed with the external thrust bearing bracket, the
Alliance rotor was found to be almost as strong and far more
rugged than the much larger ham rotors. The article was in QST
sometime between 1965 and 1967.

73, Barry WA4VZQ

Maybe you ought to check out "FTA" reciever on the web..several
sites...but be carefull there are some scam sites out there...


Graywolf wrote:
George,
wrote in message
news

Thanks for the info. I had originally thought there was a DC and
it
was reversed by polarity. This is a more unusual setup, at least
from
what I am familiar with. I find it hard to figure out how that
capacitor causes the reversal, but as long as it works. If I am
correct, this tells me that one wire is forward, on reverse and one
common (ground). That leaves the 4th. Let me guess, that one
controls the indicator position, and I would guess thru some sort
of
resistance variation ???? The rest and what you explained makes
sense.

The capacitor, in series with one winding changes the AC phase
of the applied winding voltage. Remember I said it was a two-
phase motor.

The indicator function is not always that simple. Alliance
made one rotor where the control box had its own synchronous
motor that turned the same speed as the rotor. You turned the
knob to the desired azimuth which closed the internal switch.
The switch was opened when the position of the motor in the
control box matched the azimuth setting. However, occasionally
the two motors would get out of sync with each other. Turning
the knob to first one end of its range, letting the internal
motor stop, and then turning the knob to the other end of its
range and waiting for the internal motor to stop would
synchronize the two. This worked by having one of the two
motors reach its mechanical stop while the other still turned.

Another version used a rheostat winding in the rotor unit that
supplied a meter in the control box. This is a special AC
meter and one which is not easy to duplicate. Yet another
version used a switch inside the rotor that was attached to a
gear such that the switch was momentarily closed every few
degrees. In the control box, there was a solenoid that pulled
a ratchet that drove the indicator mechanism. The indictor
jumped in rather coarse steps and clicked loudly.

Probably the most modern system Alliance made used a five-wire
cable. The rotor had a much higher resistance internal
potentiometer than the older models. It was fed from DC and
drove a null-balance circuit. The control box had a matching
potentiometer, and the motor direction and the starting and
stopping was controlled by whether the resistances matched each
other.

I recall trying to find some of those non-polarized caps for a
speaker
crossover setup. Not easy to find. I never know about using two
standard caps in that manner.

Non-polar electrolytics are two aluminum foil sheets coated
with the anodic oxide film wound together with a small moist
separator in between. Unlike conventional electrolytic
capacitors, they cannot be reformed and they do not heal.
Hooking two conventional electrolytics like I suggested forms
the same capacitor but it is physically larger.

Send me your email address and I will send you two articles on
electrolytic capacitors you might find useful. Take out the NO
SPAM in the address below to email me.

PS. How would I determine which is the common wire? I would assume
the other two don't matter, it either turns one way or the other.
The
4th, I am not sure how that one would be determined.

Get out the venerable old ohmmeter. The motor windings have a
moderate resistance, although I don't remember the value (and
very old Alliance units used much finer wire too). You should
find approximately the same resistance from one wire to two
other ones. This is the common connection. To verify, the
resistance between these two other wires should be double this
resistance. Between common and the indicator wire, you may
measure anything from a few ohms to an open circuit depending on
which model is installed.

Back in the 1960's, the ARRL did some tests on antenna rotors.
When installed with the external thrust bearing bracket, the
Alliance rotor was found to be almost as strong and far more
rugged than the much larger ham rotors. The article was in QST
sometime between 1965 and 1967.

73, Barry WA4VZQ