I currently run a 95T in the base with an antron 99 and 100ft of RG8X. Recently i have been informed that i am coming over everything in the house. Wireless headphones/ stereo receivers TV's just about everything. i am not running the 95t at full power but am curious if there is anything i can do to try to eliminate the rfi i am causing with in my house. my dad told me to fix it or dont use the radio, and reading the mail can only be fun for so long, especially when you have a microphone in hand. i have a lot of coax in the house. my question is, Could i coil a length of it an make a choke to try to eliminate rfi? should i buy a low pass filter or should i get another antenna.
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95T RFI with Antron 99
- Thread starter bigred222
- Start date
The problem is that there's too much RF for the devices being interfered with to handle. Getting that RF further away from those devices, and/or limiting the amount of RF reaching those devices is about the only 'cure'. One of the ways that RF is getting to those devices is that the feed line -IS- part of the radiating antenna. The 'A99' uses the feed line as it's 'other half' (so does the IMaxx). The bad part about that is that the antenna it's self put's more RF out than anything else does. Keep that in mind. Putting an RF choke (coiled up feed line) near the antenna is certainly one possible way of limiting all that RF floating around. Try it, what can it hurt? It also may not do much, if anything.
The other part of that RFI problem is that those devices getting interfered with are Part-15 thingys. Tht means they can't produce any interference, but they have to -accept- any interference they receive. Read the little sticker that's on all of those devices except most TVs. Those TVs are also Part-15 devices so they have to 'take' it too. Howzat for a complication, you try explaining it to the one being interfered with!
- 'Doc
The other part of that RFI problem is that those devices getting interfered with are Part-15 thingys. Tht means they can't produce any interference, but they have to -accept- any interference they receive. Read the little sticker that's on all of those devices except most TVs. Those TVs are also Part-15 devices so they have to 'take' it too. Howzat for a complication, you try explaining it to the one being interfered with!
- 'Doc
i believe Shockwave suggested the sirio gain master antenna for use on 11meters and was explaining about how it has a large coil that reduces the amount of rfi produced by the radiating element. only problem is, its 180 bucks for a vertical. id like to see some more reviews on that antenna.
Gain-Master, the new reference in its class of antennas
Gain-Master, the new reference in its class of antennas
I think Doc's point is well taken. At least, it should be.
There are other factors of course. Using a balun/choke is no guarantee at all. Wouldn't hurt to do it anyway.
The end fed half wave A99 is notorious for being a real stinker. That has been my experience as well. Shockwave's suggestion is a move in the positive direction.
The other side of the coin to all of this is the radio. If you yanked out the AM Limiter, put it back in. If you spread the 54mhz trap coils, then restore them. Keep the modulation at/below 100%. Those are three common things that might have been done to the radio that can be reversed. Better off to restore them anyway. Send your radio to a real tech and have him give it a clean bill of health. If the radio had all of the stops taken out of it, then it is time to turn that around. Eliminating as much spurious radiation from the source may not cure this situation, but it sure won't hurt it either and should help it considerably.
Power output is also a huge contributing factor. Add in the proximity to electronics that have no ability to defeat it and there is a conflict waiting to happen.
Use SSB mode instead of the power struggle on AM. You can use less power and get good or better results with lower power anyway.
Adding a Low Pass filter is another thing that may help.
Putting bypass caps in the equipment that is having problems is another. But if you are also bleeding into the neighbor's equipment too, then this situation may prove to be an uphill battle.
If all else fails, put the radio in you car with a decent antenna and find a nice hill to park and transmit from.
There are other factors of course. Using a balun/choke is no guarantee at all. Wouldn't hurt to do it anyway.
The end fed half wave A99 is notorious for being a real stinker. That has been my experience as well. Shockwave's suggestion is a move in the positive direction.
The other side of the coin to all of this is the radio. If you yanked out the AM Limiter, put it back in. If you spread the 54mhz trap coils, then restore them. Keep the modulation at/below 100%. Those are three common things that might have been done to the radio that can be reversed. Better off to restore them anyway. Send your radio to a real tech and have him give it a clean bill of health. If the radio had all of the stops taken out of it, then it is time to turn that around. Eliminating as much spurious radiation from the source may not cure this situation, but it sure won't hurt it either and should help it considerably.
Power output is also a huge contributing factor. Add in the proximity to electronics that have no ability to defeat it and there is a conflict waiting to happen.
Use SSB mode instead of the power struggle on AM. You can use less power and get good or better results with lower power anyway.
Adding a Low Pass filter is another thing that may help.
Putting bypass caps in the equipment that is having problems is another. But if you are also bleeding into the neighbor's equipment too, then this situation may prove to be an uphill battle.
If all else fails, put the radio in you car with a decent antenna and find a nice hill to park and transmit from.
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The information on that link is typical advertising B.S. It combines the 'mystical' 5/8 versus 0.64 wave nonsense, mixed with a misrepresentation of the radiator's actual 'electrical size', and some sort of el-toro 'poopoo' about coil size/radiation efficiency. You believe anything you want, but please don't try to make it some sort of miracle antenna.
- 'Doc
- 'Doc
Check your source again 222, I don't think Shockwave meant to say the coaxial choke coil on the Gain Master reduced the RF produced by the radiating element.
If he did say that, he probably meant the choke did a really good job of reducing the CMC's flowing on the feed line below the choke instead.
IMO, the setup for the GM is the most effective choking arrangement I've seen in my experience trying to mitigate TVI type problems, and I don't think the idea is just BS like 'Doc is suggesting. If this antenna has any real advantages compared to other CB verticals...I think this choking application is the big advantage. The bandwidth may be of some notable advantage as well.
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The GMs 16 turns of rg58 size cable on a 66 mm former is the best choke I've tried on 27 - 28 mhz . Try the choke see if that helps before you spend any hard earned dollars. When I first saw the GM I thought it was BS to. I built one and did a side by side test with my imax (same height and same length of cable run into a ant sw) I'm a believer ! Sold my imax ,Iv'e since built 6 gms for 11 m and 6m .Is it magic, no. But it's not BS either I think it's a good design, quiet, performs well, absolutely no CMC evident ,works well on any length of mast,insulated or not. and the band width is a bonus. There might be better performing 5/8 out there but I haven't found one.PS I wouldn't purchase one here , Over $300 AUD.
bigred222....
If you want to try and sort the problem using what you've already got...
Make a RF choke. Wind 5 turns of coax on a 4.5" diameter tube and have it as near to the antenna socket as possible. If you're using a metal mast for the antenna, don't let the coax touch it or you'll completely negate the whole point of doing this.
If you want to try and sort the problem using what you've already got...
Make a RF choke. Wind 5 turns of coax on a 4.5" diameter tube and have it as near to the antenna socket as possible. If you're using a metal mast for the antenna, don't let the coax touch it or you'll completely negate the whole point of doing this.
you try explaining it to the one being interfered with!
- 'Doc
That would be his dad.
i see 2 issues. first is the a99 are known for this issue. second is the coax .
id replace the coax with LMR 400f semi flexable cause its doubled shielded
and 8x isnt . may help [it has in my experience] also id user a alumin antenna
sirio m400 or 827. and make a rf choke using 8 turns on a 8 inch former.
if these antennas arent possible then buy a gain master. my tvi issues were
resolved when i scrapped my a99s/imax antennas
id replace the coax with LMR 400f semi flexable cause its doubled shielded
and 8x isnt . may help [it has in my experience] also id user a alumin antenna
sirio m400 or 827. and make a rf choke using 8 turns on a 8 inch former.
if these antennas arent possible then buy a gain master. my tvi issues were
resolved when i scrapped my a99s/imax antennas