M400 STARDUSTER OWNERS: Poll & Info please.

[Bob701]

I can't say that the Starduster has caused any RFI with my neighbors. I tested it at only 20 watts and it came through the TV in our bedroom upstairs. So I'm going to assume that at higher power outputs they may get some RFI, too. Or maybe the RFI falls off quickly over distance. I'd like to use a field strength meter to find that out.

If you look at the photo posted above you can see the tree behind my lower roof. Behind that tree is the neighbor's house and it may be 25' from the tree. And that tree is only 4' from my house. So the back of their house is less than 45' from the antenna.

They may not be getting any with the Starduster. As it's the weekend today is a good day to do a little testing, talk with them and find out.

Thanks for the GM info.

Signals of all the local operators were S-7 to S-9. I think the one mast/antenna was effectively blocking signal in one direction becuase of its proximity to the other.

not sue why you,d get rfi issues with the starduster???? the imax i could mine was horrible.
the one operator that was lost on the imax was his signal really low s-1 or lower?? if so
the high noise level of the imax is probaly to blame.if ya do get a gain master make sure
theres no other antennas around .and get it up at least 30 feet. from what ive read here
this antenna likes to be alone in the sky. and other antennas seem to hinder the performance of it.

 

[Bob701]

Thank you Marconi.

And you are correct. It was the Imax for sure. I have been testing the SD at low power and have found TVI to be an issue in my own home on the second floor only.

That SD sits on 2 -10' pipes putting it about 12' above the roof of the second floor. And the bedroom with the TVI shares the wall with the mast for the SD so the antenna is right over the top of that room with the TV.

I figured if I can eliminate or reduce TVI there I'm heading in the right direction with the neighbor's RFI.

But it may just be a proximity/overload issue and the RFI/TVI may fall off rather quickly with distance on the StarDuster.

No you don't have to back out the vertical, but you will have to take the antenna apart at the hub to get to the feed point connector. Then squeeze a little Stuf inside the PL259 and re-attach it.



Hotrod, I don't think Bob701 indicated that his SD'r made TVI for his neighbor, I think he said it was his Imax, but Bob would know best.

 

[hotrod]

Thank you, Hotrod.

As soon as I get the RFI issues worked out with the neighbors I will be comparing the Imax to the Starduster on transmit for local and DX. And I will happily share my findings here with everybody.

One issue I have noticed is that the Starduster completely blocks out a local S-7 signal to the Imax in some situations.

3 local were chatting the other night and I could hear all 3 perfectly fine S-7 to S-9 on all with the Starduster. One of the operators was completely lost when I switched to the Imax.

I attribute that phenomenon to the fact that both antennas are closer together than they should be. 12' or so.

From what I have read here it seems like they should be at least one wavelength apart...if not more. This is not a permanent installation so I didn't bother to adhere to that rule.

from the looks of this pic id say try moving the antenna to other side of house.sounds like
its just too close to your bedroom tv.ortry raising the antenna great thing with the duster its very light weight so 50-60 feet at the hub wouldnt be a issue

 

[Bob701]

Those are always and option Hotrod, thank you. Raising it where it is will require guying for sure. Moving it will require a whole lot of other things.

I'm not so concerned about TVI/RFI at home as it's only affecting the second floor here. I am concerned about the intereference to my neighbors,though.

I'll get it worked out.

from the looks of this pic id say try moving the antenna to other side of house.sounds like
its just too close to your bedroom tv.ortry raising the antenna great thing with the duster its very light weight so 50-60 feet at the hub wouldnt be a issue

 

[Needle Bender]

I hope I'm not repeating someone's post but I have to mention that one issue with the Starduster is the fact it's a balanced antenna fed by unbalanced line.
One way that issue can be dealt with is to mount it to a short, 12" pierce of tubing, making the coax connector accessible, then mount that to a short piece of 1 1/4" fiberglass rod with a coaxial choke of 5 turns on a 4" former wrapped around the fiberglass as an isolator which is mounted to the top of the mast or tower. This tends to help prevent feed line radiation and helps get your RF out of neighborhood electronics.

 

[Bob701]

Thank you, NB. I don't believe you have repeated anybody. That's an option should there still be a problem. And I don't know if the SD is problematic to the neighbors yet. I left a voice mail with them over the weekend, but they haven't called me back yet.

If worse comes to worse I will relocate the antenna/mast. And when I do that I will put up a better antenna.



If there are still issues with the SD than I may just move the whole deal off the roof and acros

I hope I'm not repeating someone's post but I have to mention that one issue with the Starduster is the fact it's a balanced antenna fed by unbalanced line.
One way that issue can be dealt with is to mount it to a short, 12" pierce of tubing, making the coax connector accessible, then mount that to a short piece of 1 1/4" fiberglass rod with a coaxial choke of 5 turns on a 4" former wrapped around the fiberglass as an isolator which is mounted to the top of the mast or tower. This tends to help prevent feed line radiation and helps get your RF out of neighborhood electronics.

 

[Needle Bender]

OK, and I have to say, I enjoyed my Gainmaster all weekend DXing into Europe and they were mostly as impressed as I am with the darn thing. What a performer!
Keep that in mind if you decide to buy a new vertical.

 

[Bob701]

Thank you, NB. I don't believe you have repeated anybody. That's an option should there still be a problem. And I don't know if the SD is problematic to the neighbors yet. I left a voice mail with them over the weekend, but they haven't called me back yet.

If worse comes to worse I will relocate the antenna/mast. And when I do that I will put up a better antenna.

I hope I'm not repeating someone's post but I have to mention that one issue with the Starduster is the fact it's a balanced antenna fed by unbalanced line.
One way that issue can be dealt with is to mount it to a short, 12" pierce of tubing, making the coax connector accessible, then mount that to a short piece of 1 1/4" fiberglass rod with a coaxial choke of 5 turns on a 4" former wrapped around the fiberglass as an isolator which is mounted to the top of the mast or tower. This tends to help prevent feed line radiation and helps get your RF out of neighborhood electronics.

 

[hotrod]

well if you was coming over there stufff id think they,d tell ya about it very
quickly.thats always been my experience with the a99/imax/shaksphere type
fiberglass antennas.the only setup i see from that sd,er is like a maco /penatrator 500
never tried the gain master ,but from history i had terrible luck with fiberglasss antennas

 

[Bob701]

Thank you HR.

Funny situation I have. I was running a fiberglass antenna before (Anttron 305) and I had no issues. Since taking a break from radio my neighbors may have installed a new entertainment system at home, though.

I thought it may have been going from a 1/2 wave to the .64 of the Imax that did it.

It's a mystery...just like an antenna.

well if you was coming over there stufff id think they,d tell ya about it very
quickly.thats always been my experience with the a99/imax/shaksphere type
fiberglass antennas.the only setup i see from that sd,er is like a maco /penatrator 500
never tried the gain master ,but from history i had terrible luck with fiberglasss antennas

 

[BammBamm]

After reading the posts here it seems those that have both the SD and the Imax prefer the SD as far as TVI and wind load goes? I'm not happy with my current Imax but hadn't thought about the M400....until now. I can't decide.

 

[Marconi]

Thank you Marconi.

And you are correct. It was the Imax for sure. I have been testing the SD at low power and have found TVI to be an issue in my own home on the second floor only.

That SD sits on 2 -10' pipes putting it about 12' above the roof of the second floor. And the bedroom with the TVI shares the wall with the mast for the SD so the antenna is right over the top of that room with the TV.

I figured if I can eliminate or reduce TVI there I'm heading in the right direction with the neighbor's RFI.

But it may just be a proximity/overload issue and the RFI/TVI may fall off rather quickly with distance on the StarDuster.

As I understand the issue of TVI, the problem can present from the antenna itself being too close to a conductor, so TVI is not always errant radiation, from the feed line and/or mast.

If you guys study the Starduster Patent #4208662, Patent US4208662 - Omnidirectional, vertically polarized antenna - Google Patents. Pay particular attention to the info in the Patent at reference column #2 lines 63-65, and beyond. This is the magic for the bazooka balun idea and is a good concept to learn and understand.

I think you can figure out this design goes way back to at least 1937, when the idea of minimizing feed line radiation was first being addressed. Check out this Patent, Patent US2184729 - ANTENNA SYSTEM - Google Patents

I first became interested in this in the 80's on reading this article. http://www.arrl.org/files/file/Technology/tis/info/pdf/8004019.pdf. This very technical study discusses on the front page, at least one big idea for a solution using a bazooka type balun design was presented. That idea is basically the design that the Starduster is designed and constructed around. IMO, the bazooka is not fully implemented in the SD'rs instructions, but I think it works well even so, if elevated properly and set well into the clear. A friend of mine designed a better bazooka design that he used very successfully on his Starduster, is simple to install, and does not require an insulator.

As you read pay close attention to the length of the balun idea discussed.

If you study the old Avanti Sigma4 construction manual, you will note that they too instruct a bazooka balun idea. However, they don't go into any real details either, but I think this idea is in part what they were suggesting.

 

[Bob701]

Why aren't you happy with your Imax?

My Imax works well. It's a little noisier than ther M-400, but the Imax puts out a good signal. I have had no problems with the Imax other than the RFI to the neighbors -who are pretty close -and it being slightly noisy in my particular environment Which, I think, is a fairly noise place electrically.

For the price the M-400 is a cheap experiment and it just so happens to work pretty darn well, too. Spoke with the UK this morning on it and I have to give it the nod on receive....MOST of the time over the Imax.

After reading the posts here it seems those that have both the SD and the Imax prefer the SD as far as TVI and wind load goes? I'm not happy with my current Imax but hadn't thought about the M400....until now. I can't decide.

 

[Bob701]

Thank you Marconi. I will give all that a look later. Off to work in a few.

As I understand the issue of TVI, the problem can present from the antenna itself being too close to a conductor, so TVI is not always errant radiation, from the feed line and/or mast.

If you guys study the Starduster Patent #4208662, Patent US4208662 - Omnidirectional, vertically polarized antenna - Google Patents. Pay particular attention to the info in the Patent at reference column #2 lines 63-65, and beyond. This is the magic for the bazooka balun idea and is a good concept to learn and understand.

I think you can figure out this design goes way back to at least 1937, when the idea of minimizing feed line radiation was first being addressed. Check out this Patent, Patent US2184729 - ANTENNA SYSTEM - Google Patents

I first became interested in this in the 80's on reading this article. http://www.arrl.org/files/file/Technology/tis/info/pdf/8004019.pdf. This very technical study discusses on the front page, at least one big idea for a solution using a bazooka type balun design was presented. That idea is basically the design that the Starduster is designed and constructed around. IMO, the bazooka is not fully implemented in the SD'rs instructions, but I think it works well even so, if elevated properly and set well into the clear. A friend of mine designed a better bazooka design that he used very successfully on his Starduster, is simple to install, and does not require an insulator.

As you read pay close attention to the length of the balun idea discussed.

If you study the old Avanti Sigma4 construction manual, you will note that they too instruct a bazooka balun idea. However, they don't go into any real details either, but I think this idea is in part what they were suggesting.

 

[Marconi]

Why aren't you happy with your Imax?

My Imax works well. It's a little noisier than ther M-400, but the Imax puts out a good signal. I have had no problems with the Imax other than the RFI to the neighbors -who are pretty close -and it being slightly noisy in my particular environment Which, I think, is a fairly noise place electrically.

For the price the M-400 is a cheap experiment and it just so happens to work pretty darn well, too. Spoke with the UK this morning on it and I have to give it the nod on receive....MOST of the time over the Imax.

I have never been impressed with the several Imax antennas I've had over time at my location, but I can't say they are bad performers. The air-waves are often full of Imax signals.

When I hear that said, I suspect bad antenna, bad coax, bad connectors, bad install, bad height selection, or bad ears (noisy), so the antenna gets a bad wrap all too often. In fact, most complainers of CB antennas, for sure, probably fall into one or more of these categories.