Space, the frontier I don't have! a/k/a "need a positioner smaller than a 4DTV that WORKS!"

[radio]

I'll try not to bore anyone as I ask for advice and help with an FTA positioner situation.

I'm living in a small space by choice.... (some of the time, that is... I have a permanent address at a great distance away from my business...that remains for sale. I hope it sells soon.) Warm in the winter, cool in the summer, and quite roomy for what one would think! Except where room for home entertainment equipment is concerned.

Connected to my space are (2) separate Birdview dishes. One is not set up to move, it brings me W-5 subs through the DSR-410 box. Happily and easily.

The other dish was my 4DTV setup, slaved to FTA, now dedicated FTA. Here's the problem. Space. The frontier I don't have on my counter.

I've tried two alternatives to driving my birdview with the 4D. Both the G-box and the V-box units fit better physically but error-out immediately when trying to read pulses. Not due to "overload" (that's a different error) but because of the RF radiated by 3 towers of AM (and 212 watts of FM) in my back yard. Pulses coming back are regular and verified.

The only difference I can see between the V-Box/G-box and my 4D being used as a positioner successfully is that the 4DTV unit is heavily shielded with a metal cage, and...when we changed its battery, we noted a HEAVY, LARGE RF "toroid" coil on the mover's wires just before they reach the terminals on the back of the unit.

I believe that a heavily shielded (smaller footprint) positioner would work in place of the 4D unit, given that the 4d moves the dish flawlessly, and two others do not. This rules out any issue with the reed switch, wiring, or dish setup. My question is this:

Has anyone taken apart a G-box/V-box and could they be equally shielded? or....better yet, (here's the part I'm really curious about) could an older General Instrument positioner 350ips unit do the job? I don't know much about these, can't find any manuals online, but it appears to be a "stand alone" positioner that may just use simple front panel numbers and East-West commands. (no interfacing with the FTA receiver, but a good, reliable, heavy duty power supply, probably well shielded, and....compatible with a standard pulse-return/36 volt system.

Do I have the proper information on the 350 IPS? Is it a stand alone positioner? Would it work with reed-switch standard setups and operate manually?

As you can see from the photo, I'm a bit "space challenged" and want to clean up the setup a bit.

Any help, suggestions, ideas welcomed! For now, my 4DTV is a (very large) dish mover only. It didn't like the "work around" anyway for subs, and I've got a 410 for that, so it can move the dish til a suitable replacement is found.

-radio

 

[Lak7]

Can you heavily wrap the GBox in tinfoil to see if shielding helps?

 

[radio]

Well, that may be one option. One of the problems I think I run into is that the older equipment was made with a real metal chassis. Today, everything is plastic, and very cheaply put together. (no offense, sponsors)...but its not built like we had in the 1980's! I thought the system may ground itself when the coax was connected through the FTA and to the dish, but that didn't seem to make a difference.

 

[Cham]

Interesting dilemma...
I have used a Kw or more many times on 80m (3.7MHz) and never have had a problem with RF messing up the counter... which actually suprises me. The antenna I use is right above the dish and mover(s). The control cable I am using is the standard satellite ribbon cable from CommScope and has a shield for the positioner sensor leads. Think there are four conductors in the strand; two I use for my particular reed sensor, one spare for hall effects and other sensors, and the shield/drain. The shield is bonded at the receiver end only. I use a Uniden analog/VC2 receiver as the dish mover and the actuator is made by Von Weiss. The latter is all metal around the sensor and motor, attached to the dish mechanism with metal clamps so it would be well grounded at the dish end.

This is sort of a heads-up for me as I would likely be in the same situation if my old positioner receiver dies and I replace it with one of the G/V box units. Will be interested in the outcome!
Best of luck,
-C.

 

[radio]

Interesting dilemma...
I have used a Kw or more many times on 80m (3.7MHz) and never have had a problem with RF messing up the counter... which actually suprises me. The antenna I use is right above the dish and mover(s). The control cable I am using is the standard satellite ribbon cable from CommScope and has a shield for the positioner sensor leads. Think there are four conductors in the strand; two I use for my particular reed sensor, one spare for hall effects and other sensors, and the shield/drain. The shield is bonded at the receiver end only. I use a Uniden analog/VC2 receiver as the dish mover and the actuator is made by Von Weiss. The latter is all metal around the sensor and motor, attached to the dish mechanism with metal clamps so it would be well grounded at the dish end.

This is sort of a heads-up for me as I would likely be in the same situation if my old positioner receiver dies and I replace it with one of the G/V box units. Will be interested in the outcome!
Best of luck,
-C.

Thank you for the kind words! It's both our daytime 4.7kw of AM and the fulltime FM, but likely the AM that causes the issue. Even at night, its 330 watts directional toward my dishes, which is probably the issue. If it weren't for running a disconnect-style cable through the floor in this classic trailer and having sealed it up, I'd run new shielded wire. And, may run some out to the dish anyway just as a "test." Perhaps some quad-shielded coax, come to think of it would serve to pick up my pulses. Its only about a 60 foot run. hmmmm.....

Again, thanks for the thoughts!

 

[Anole]

cheap to try:

Around here, I'd go to a local HAM shop, and get some of the inch-diameter ferrite doughnuts of a color to match the general frequency you think is causing the problem.
Shouldn't be any effort to put some on the pulse wires on the back of your Gbox, and out at the reed.
Unhook, run the wire through, and thread it back through the doughnut half a dozen times, and reconnect.

I'd do it to my motor wires, as well.
If that doesn't help, then it'll be time to get serious.

You live in a metal trailer, as I recall.
Is the outside of it properly grounded?
If so, I'd think that would act as a pretty good shield (to replace the plastic chassis)
Then, I'd look to see what other entry wires might bring the AM station into your shielded home.
Maybe the phone wires? I'd shove a toroid on them as well.
Probably best to put the doughnuts as close to where the wires enter the trailer, maybe even inside and outside.

There are commercial RFI filters. They're little more than a series coil, and...
... some 1000 pf caps on each side of the coil, to ground.
Maybe even some of the AC power connectors they put on computers would work.
They often have RFI filtering in them, and you might get some for free by tearing up dead computer power supplies (?)

 

[radio]

Excellent! Yes, I do live in a metal trailer. I'll call it a "Classic" so people don't get some wrong idea...(chuckle, grin, laugh)
Good idea on the shielding! I don't have any wired phone service, but....there's plenty of chances for AM to come in. As you probably know,
I live on the property of the AM, and actually over the ground system of the station. AM requires a ground plane, and every 3 degrees, (120 of them as math goes) a radial goes out 199 feet, the same length as my towers, so Im probably right over a few.

I do like the doughnuts idea on both sides of the wires. And, was thinking of doing it on the motor wires, since anything can conduct RF to just about anywhere.

Will keep you posted, and thanks for the ideas!

Just for kicks, do you happen to know anything about that GI unit I mentioned? Is it standard in terms of how it runs with 36 volts and pulses? I have a good feeling that being from the older era, it may be the cat's meow for this, but....like most other site users, I don't back down from a good RF, Satellite, or similar problem. And, I love to see it fixed!

 

[Bongu]

I didnt see it mentioned here that you only ground ONE END of the shield on the cable of the sensor wires. the ground should be OUTSIDE so any stray RF goes to ground outside ASAP instead of travelling over the cable to the inside of the dwelling or to a grounding block just before going inside.

I see you mention that you have spare antennas, i mean conductors in your cable. The spare conductors are great antennas if you get my point. Ground the spare conductors outside also. With that level of RF that close, grounding all unused conductors is necessary.

 

[radio]

True on the grounding at one end. (dish end.) The wires are, but...good point on the "extras"....I'll try that first. If they're radiating RF, that could solve the problem easily. Will report back! Thanks!

 

[oldsatdude]

Hey "Radio",

Glad to see someone still using a Birdview dish and would like to say I have serviced many in the past years using a number of different receivers. If you are looking for a solid mover with a heavy can on it, then search for a Uniden or General Instrument or maybe a Chapperal receiver. The reason Motorola receiver is a beast is because General Instrument built the first 4DTV receivers and Motorola bought them out. If you check with some of the used satellite receiver companies and ask for the old stuff, you may be able to obtain one. Going back a ways, STS built a separate dish mover with a two digit number to track the birds and polarization H/V. It was programmable and you just store the position.

I engineered a 5kw AM station and you are sitting in a field of RF and anything with a wire connected to it is a radio. ( I'm sure you know that!) RF will penetrate everything.(That too!) Some times you need to move stuff below the counter top or down to the floor. Your box that won't work, may not because its next to the TV or maybe in a HOT SPOT of RF. I ran some old Gentner phone stuff (analog) in a building with a 5kw rig and a few guys say it wouldn't work, but I kept looking for the sweet spot. Eventually it did work. The building sat in the ground radials and one guy even hooked the grounds of the main tower to the rebar in the slab. Put conduit in the slab from studio to studio and then ran the multi pair cables with high quality shielded wire. It never worked. We had three studios in the building all running different programs. Past engineers couldn't keep the cross talk out and I rewired and rerouted and and moved thing around and was very successful. Nothing in the slab now.
The receiver uses pulses from the reed on a series circuit so one side is ground reference and a shield won't stop the RF if it is just blowing thru the box cover. Wrapping it with foil will make a bigger antenna, most likely. I never had much luck with the ferrite coils. You may want to run a copper strap up into the house and along the wall if possible to absorb the RF and equalize the ground inside.

Good luck to you!

 

[radio]

Your post and reply made my night! Yes, Birdview was (and in my book still IS) the "best of the best" for hardware. I agree with you on the needing an old dish mover. I have hopes that a GI 350si listed on Ebay may work. If its built like the 4D is with a good heavy cage, and some RF shielding it may work well. Unfortunately, nobody thus far has had any info on them, and the seller thought it was a "receiver" which it is not, obviously.

RF truly IS a pain. I bought this station when it was off the air, and brought it back to life. Replaced a Continental tube transmitter with a new B-E 6kw, which cleaned up much "splatter" and bad modulation. (our old one was hit by lightning.).....Managed to build a prod room with no RF, but my main studio's phones still have some when we switch to high power. I believe the heavy shielding and build of the 4D is why we have no problems moving the dish with it.

It has been suggested I ground my home a bit better, and that should be easy to do. I'm a fulltime RV'er, even through Michigan Winters. My state's been hit tough with the economy and bad management, and my old home over 100 miles away has, until recently had no interest in terms of buyers, so I live at my business, the AM station quite comfortably in a 1985 classic AVION silver trailer. Warm, Dry, wireless internet, DSR-410, and FTA. I can't complain. Will try to ground the aluminum shell. I had hoped the piped-in LP did that, but there's no guarantee that is the case.

Our ground radials are quite good, we found them all when running new wires to our FM on the middle AM tower, and running new high-power cable for our Daytime array on the north of (3) towers. Was amazed that a 50 plus year old grid was that good!

Will be doing some weekend work on the project and will report back.

Have you ever worked with the GI unit I described? I just have a feeling it would be fine....or...convert the birdview BACK to its old potentiometer system from the pre-IRD era and use an original birdview numerical drive, which would be fine. Not automatic, but fine.

Again, thanks for the great note. Keep in touch. Learn about my station if you like at www.i1430.com

 

[oldsatdude]

Great, I'm sorry you can't find anything on the GI. Also, I have not worked with any GI stand alone positioners. You may want to look at your "in box" on the top of the forum page under "notifications". I sent some info directly to you. Don't count on the LP for ground. I wouldn't ground the shell either. You may end up with a huge difference of potential with grounds and may burn up a wire or invite lightning in. Your story about the Continental rig and changing over to BE is the exact story of the place I formerly engineered. Splatter and all. Thus the economy is bad everywhere as I can't land a new gig. Management was killing me with no respect or even a raise after 5.5 years of service and I had to close the book on them. Sad that people in charge don't listen and it cost them more in the long run.
Happy to keep in touch with you. I did a lot of rebuilds on the Birdview mounts for customers and they are a stout dish.

When I finish this post I will cruse over to your station site. Thanks for the invite. 8^>

 

[gardenman2002]

Radio,
I agree with oldsatdude. If the rf is at a sufficeint level, no mater what , you will get an rf signal impressed in the box. Only two suggestions i have is use a commercial inline band reject filter just before it get to the receiver. Other suggestion, is homebrew a box so you can physically ground the circuit boards at each ground point and then scrounge some solderable metal and make shielding boxes out of them.. Also , you could run galvanized counduit which will give some shielding to the cable.But these are just suggestions.
hope it works out. rfi is a big problem with some equipment and also when oveloaded with a strong signal. One more. try to convert signal at dish to fiber optic..

 

[radio]

Yes, RF is fun! Thanks for all the suggestions thus far. Have not had a chance to experiment. Between work and the "real" winter in Michigan, its been a battle, but hope to do some soon. What's really "odd" is that the 4DTV has EXCELLENT RF rejection, and works as if it doesn't see the RF at all. Metal Cage. RF forms on the motor connections inside. And, it works even without coax cable hooked up which helps provide a ground through its shield! Wouldn't it be nice for all of us using 4D's to move our FTA boxes if someone could design something to interpret the disecq or other signals from an FTA box into RF commands for the 4D? It would make life easier for many on this site. Or, if there was a direct connect way to take logic from the FTA and FEED it to the 4d!

That would make keeping the large 4D on the counter much more palatable over a smaller, more modern V box or G box.

 

[Cham]

One of the sponsors was talking about a G/V box system with motor and skew control for polarotors... Still hoping for this some day. Might have to switch to an LNBF and throw away the Chaparral to make this happen (one of the Murphy laws I think).
C.

 

[radio]

Ah, nice..but...."all in one" offers more of what I need....RF shielding by a usually metal chassis......and multiple chances to ground through antenna loop-through's, OTA antenna in, etc....where the stand-alone movers offer much less and come in (no disrespect intended) much cheaper plastic enclosures.

 

[oldsatdude]

Radio,

Any luck finding a smaller positioner?