REMOTE Tuning Vertical

[flintstone mop]

Hello my friends in Radio
I would like to remote tune my Cushcraft MA160V vertical antenna. I don't know whether to use 110vac as a control voltage or "low voltage DC".
I presently have a nice waterproof box with a nice big vac variable driven by an AC operated motor. It was in a power control circuit in an Gates transmitter. All I need is three wires to select the "other winding". The motor has two 110vac windings to reverse it.
I want to connect the var cap in series with the feedline to "shorten or lengthen" the vertical element. This was used successfully with the Unihat vertical, so I could move up and down the band.
The other component needed in this is a variable coil that is shunted across the coax to give me a better SWR or impedance match. I am presently using an 18 turn coil wound on a 2" inch diameter form. By adjusting the capacitor and coil I can go anywhere in the 160M band.
I'll inlcude a pic in another posting here of the tuner box. Maybe someone has a lead on a "low voltage DC motor" for the capacitor. How can I motorize the coil? I'm not sure what uh the coil is and what can be done to make it mechanically driven by a motor. I'm not really good with mechanical ideas.
Any help would be appreciated.
FRED

[flintstone mop]

OK Gang
I included a pic of the tuner box that could be part of this project. The coil inside was a wreck from a Gates transmitter, that was damaged in shipping. I would just use the taps.
I'm thinking that a motorized coil would be neat.
Below is a link to an ebay sell of a Ham inductor that a motor could be added to.

http://cgi.ebay.com/Variable-Coil-Inductor-Used-Mil-Spec-Ham-Radio_W0QQitemZ350010010955QQihZ022QQcategoryZ1502QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Thanks for looking
Happy New Year
Fred

[KL7OF]

The world of auto parts can provide many hi torque, 12 vdc motors for projects like this.  Electric window motors, windshield wiper motors, electric antenna motors, seat adjustment motors.......etc...some are direct drive and some come with gear reduction.......I have used the drivers side window motor from a Toyota to operate a variable vac cap....see your local auto wrecker....The good ones have these parts removed and available for your inspection.

[flintstone mop]

That's a good thought about junkyard stuff. My concern with 12 volts would be sending that voltage about 400 feet to the antenna. It might be more cost for the wire to carry the additional current without excessive loss.
I'm guessing that a DC window motor would draw about 5 amps?

Fred

[KL7OF]

I don't know what the current draw would be....There isn't much torque required to turn a cap.....  The power supply could be mounted at the cap location ......

[W9GT]

I have often wondered about using some of those "cheapie"  battery powered electric drills and other small power tools typically available from Harbor Freight and other places.  I have seen 9V and 12V battery drills for less than 10 bucks.  Seems like these would be hi-torque, they are variable speed....might work great for remote tuna applications or remote switching applications.  They are also reversable and easily coupled to a 1/4"- 1/2" tuning device shaft with the drill chuck.   Might really be nice for turning vacuum variables and/or rotary inductors.  Also you could locate the DC supply remotely at the tuna location...by running a buried power line to the base of the tower.  That is what I did here to run my prop-pitch rotator power supply.  It puts out approx. 28 VDC at mucho amps and could run a lot of the remote motors in addition to the rotor very easily. Just some ideas.

73,  Jack, W9GT

[Jim, W5JO]

Two considerations Fred, If you use 115 volts to control something that reduces the size of wire needed but increases the chance of hurting someone else.  The lower voltage stuff gets out of that realm.  Notice the Hygain 400 rotor of years ago.  It used 110 volts up to the rotor and the new version is 28 volts to avoid product liability.

Second, the roller inductor is subject to dirt, water, and all sorts of contamination.  The tapped coil is a much better choice according to Johnson who went from the roller inductor in the Viking series to a tapped coil in the Ranger/Valiant series.  Put it this way, exposed to outside temp/humidity, have you ever seen a roller inductor that made reliable contact?

[Steve - WB3HUZ]

Second, the roller inductor is subject to dirt, water, and all sorts of contamination.  The tapped coil is a much better choice according to Johnson who went from the roller inductor in the Viking series to a tapped coil in the Ranger/Valiant series.  Put it this way, exposed to outside temp/humidity, have you ever seen a roller inductor that made reliable contact?

Good point. Maybe that's why many of the remote tuners use the ribbon type variable inductors.

[flintstone mop]

All of the components are going to be in a sealed weatherproof box, so there won't be any issue with dirt and water. Looks like a Summertime project any way. It's too cold now to play with something that's working. There have been some super ideas here for powering the motors for the vac variable and the coil.

fred

[John K5PRO]

Gads Steve, I'm a little slow. That little bug on your reply that runs around in a figure 8, I could have sworn it was on my screen and i was trying to blow it off. Looked just like the bugs I get at night in here on my CRT.... Hate 'em.
73
John

[Jim, W5JO]

Fred even in a weatherproof box, the components will be subject to humidity forming water on them.  There are two ways to fix the problem.  A completely sealed box with the packs in there to absorb moisture, or on the bottom a vent to provide airflow.  Either way you will have some moisture inside.

[flintstone mop]

Thanks Jim
Having the box on some cinder blocks will also isolate the moisture intake a little, but your idea for the vents will be installed too.
Fred

[flintstone mop]

Another thought....I have a latent mind.
The enclosure is from a TMC antenna tuner. It's fiberglass so the temp changes shouldn't cause any sweating inside. I have used this box before with no dampness or rust.

Fred

[AB3L]

Fred even in a weatherproof box, the components will be subject to humidity forming water on them.  There are two ways to fix the problem.  A completely sealed box with the packs in there to absorb moisture, or on the bottom a vent to provide airflow.  Either way you will have some moisture inside.

I believe I have seen this in older fire alarm equipment, somewhere else maybe...a power resistor in the housing , or as used in parking lot gate arm controllers...a light bulb. Both will give off a bit of heat within the housing. Going to be paying for that trickle of juice though.

[ab3al]

check out max gain systems they have the motor  you needs for about 15 bucks.  I bought 4 of them for my little project

http://www.mgs4u.com/RF-Microwave/motor.htm

[flintstone mop]

Thanks for the link,,,,,,,but the microwave link was outta stock of the little buggers. I found a car window opener motor brand new on e-Bay for $19.
Fred

[flintstone mop]

I thought I would bring this back for old time's sake.
Could I have my tuner for the vertical in the shack? It would save a bundle on the 4 conductor #? stranded wire, 240 feet long.
The tuner would be a variable coil shunted across the coax and a vac variable in series with the center conductor of the coax.
Just a thought. Getting a layout together.
Fred

[Jim, W5JO]

Doing that will work Fred, but the feedline becomes part of the antenna system.  This is the solution most people use and works fine.  However when you deviate from the frequency of the antenna you introduce an impedance mismatch to the feedline.

Provided you don't exceed the voltage or current capability of the weakest link in the system, you will be fine.

[flintstone mop]

I understand about changing freq and the Z changes, but the tuner is variable and I will always adjust the elements for the 1:1 match.
I was wondering if there would be a day and night difference in performance/losses, etc, having the tuner inside the shack vs at the base of the vertical, which seems to be the norm for "tuning" a vertical.
If it's better at the base of the vertical, I'll have to sniff around for some surplus wire and sneak a purchase through.
Fred

[flintstone mop]

Hello
Light came on in head!!!! Another O.F. post. The tuner at the base of the vertical keeps the coax as a piece of coax/transmission line not part of the antenna. Gotcha
I'll be looking fer some 4 conductor stranded cable.


Fred