| Author |
Message |
    
Silverfox
New member
Username: Silverfox
Post Number: 5
Registered: 3-2006
| | Posted on Saturday, April 01, 2006 - 7:51 am: | 
|
I'm new at this hobby so please bear with me if I ask dumb questions and use incorrect terminology. Here's my problem...I live in rural Wisconsin high on a ridge. There is a neighbor right across the road that just put up a new TV antenna (no cable out here)just above his roof line that is about the same height as my roof line. His house is probably about 200 feet from my house. I'm going to put up an Imax 2000 and am shooting for 54 feet to the bottom of the ant. When I look across the road and see that TV ant sitting there I get real nervous (why couldn't he have gone with a satellite system like I did?!?). Anyway, I want to do everything I can to try and prevent TVI so I don't get into his TV. I was thinking I would get the GPK but a friend of mine who has been in this hobby for awhile thinks that getting the GPK may be counterproductive. He runs an Imax at the same height in a neighborhood without the GPK and doesn't seem to affect anyone in that neighborhood. His theory is that I will be high enough to not affect my neighbors TV and that if I install the GPK I may push the signals(?) DOWN toward the ground and, thus, get into the neighbors TV. In otherwords, he thinks the GPK may create a WORSE problem instead of curing the possible problem. From what little I know about this stuff...his theory does seem to have some merit. Frankly, from all that I have read, I don't know if the Imax GPK has any other significant advantages other than helping to shield the TVI problem so I was going to go without it until I saw my neighbor put up his TV ant. So...what do you guys think? Is my friend's theory correct? Or, should I use the GPK to try and help the possible future TVI problem? GPK or not??? I'm hoping a tech here will see this too. Thanks in advance for your suggestions.
SilverFox |
Tech808
Moderator
Username: Tech808
Post Number: 9626
Registered: 8-2002
| | Posted on Saturday, April 01, 2006 - 8:28 am: |
|
Silverfox,
You should have NO problems with TVI using a GPK kit with the IMAX as long as ALL of your equipment including your antenna, mast pipe and tower are ALL properly grounded to a Single Point Ground.
Corncob / CEF #166 lives less than 1/8 mile from me and he has 4 neighbors within 100 feet of his IMAX 200 with GPK kit and he has NO TVI Problems.
I have 6 neighbors witnin 200' of my IMAX 2000 w/GPK Kit on a tower and I have NO TVI Problems.
I have two towers up 1 at 54' and one at 36' with the IMAX and have never had any problems with TVI from the Anttron 305, or the IMAX 200 w/GPK kit.
As I mentioned above make sure that "EVERYTHING" is GROUNDED Properly, (Radio's, Meters, Coax, Switch box's, Tower, Mast Pipe, Antenna and ALL Grounded to a Single Point Ground.
Hope this helps,
Lon
Tech808
CEF808
N9CEF
CVC#2 |
Silverfox
New member
Username: Silverfox
Post Number: 7
Registered: 3-2006
| | Posted on Saturday, April 01, 2006 - 10:10 am: |
|
It helps a LOT, Lon! Thanks! I may need help in figuring out how to ground all of the equipment to a single ground point but that's what I will do. This grounding stuff seems a little complex. I see here that you should bury wires coming from the ground point...have to figure that one out! And I was wanting to use LMR double shielded coax but I will have a run of about 130 feet so I want to make it 144 feet so it is in multiples of 18 feet. THEN I want to make a choke out of the ant coax but that's ANOTHER 18 feet. Now I'm up to 162 feet! That's going to get expensive...not to mention the difficulty in wrapping the LMR400 into a choke. As I understand it the ant wire coming from the feed point is wrapped around a non conductive cylinder. That cylinder for LMR is going to have to be pretty large in diameter. I know you can use different coax for the balun but it seems to me that using the original ant wire without breaking into it would be best for a couple of reasons. Then I'll have to figure a way to attach it. I looked at Chad's balun on his pic page and may do something like that. I'm new at this but am pretty much of a perfectionist so I am trying to do all the things I see here and other places to to insure a good operating system. May as well do everything now rather than have to go up to the ant more than once. Incidentally...when I asked the engineers at Solarcon why they built a GPK for the Imax when they have always said that the Imax didn't NEED one....their answer was..."because everyone was asking for one". I'm not totally sold on the Imax GPK but the techs here say that they are a good thing to have on the Imax so...GPK it is. Thanks again, Lon. I really appreciate your help.
SiverFox |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1307
Registered: 7-2004
| | Posted on Saturday, April 01, 2006 - 1:29 pm: |
|
You will need a flexible coax if your
going to do all that bending. You may not
even need a choke. I would keep things
simple in your installment. Then change
things if needed later. |
Silverfox
Junior Member
Username: Silverfox
Post Number: 11
Registered: 3-2006
| | Posted on Saturday, April 01, 2006 - 2:30 pm: |
|
Thanks Road Warrior...I thought that I read somewhere that Solarcon recommended the choke. You make a good point...I am a perfectionist and try to do anything I do to the max, but the KISS method is often the best way to go. I'd like to just run RG8 down the pole and into my house, get on the air and have done with it. There are so many things to learn and do with this hobby I don't know if I would ever get on the air if I tried to find and do all of them. Thanks again...I think I need to step back and relook at things.
silverfox |
Hotwire
Senior Member
Username: Hotwire
Post Number: 1119
Registered: 1-2005
| | Posted on Saturday, April 01, 2006 - 2:49 pm: |
|
Silverfox, These guys gave you some good info! I would like to suggest a qaulity TVI filter along with it. If you plan to use your radio at legal power and tuned right then don't worry about tvi. If your gonna run an amp then be sure your radio is tuned properly to operate the amp. A radio that is not tuned right creates the harmonics that cause tvi and when you amplify those harmonics then you have the problems. Over driving the amp and having the mic gain to high are also big TVI causes. As long as you have a clean signal at the distance your neighbor is then your good. Of course if your gonna run kilowatts then you will cause interference regardless.
I agree with Road Warrior. Since your new to this keep it simple! Skip the choke for now and just get the station up and running. Also there is absolutly no need to have a specific length of coax for a base or mobile for that matter. A mobile antenna pretuned yeah maybe. I use the Imax and I have no ideal how long my coax is, 40 or 50 feet give or take and I have a 1.1 swr. No where in the Imax manual says to use a certain length. Just use however much you need to make it to the radio then a little extra slack in case you need to relocate the radio in the room. Some ops like to make jumpers in 3,6,9 foot lengths. Also IMHO I would just go with rg213 from Copper. LMR400 is not going to make any difference for TVI over 213. It is a better coax and provides less loss but nobody will notice the difference. good luck |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1364
Registered: 9-2004
| | Posted on Saturday, April 01, 2006 - 8:53 pm: |
|
silverfox, remember that there is just as much bad info out there as there is good info. sometimes more!
the secret is to find the right person to listen to, and trust their judgement. you will never find total agreement on anything in this hobby, but you have to trust someone right?
the person to listen to is right here in our forum and he goes by the name TECH833.
he is the most knowlegeable person i have ever come across when it comes to antennas, grounding, safety, and basically everything having to do with a radio station.
if his advice clashes with any other advice given to you by anyone else; CHOOSE TECH833's ADVICE!
he will be right.
it would benefit you greatly to use the "search" option on the left side of your screen, and do a search for any posts by TECH833.
you will increase your knowledge tenfold by reading these.
everyone has opinions; he has the facts!
also read his review of the IMAX antenna called, "imax exposed". there you will find the reasons to use the GPK and what it will do for you.
have fun!
matt |
Scoobydoo
Intermediate Member
Username: Scoobydoo
Post Number: 104
Registered: 8-2005
| | Posted on Saturday, April 01, 2006 - 10:09 pm: |
|
Ditto on what Kid says!!!  |
Silverfox
Junior Member
Username: Silverfox
Post Number: 15
Registered: 3-2006
| | Posted on Sunday, April 02, 2006 - 10:18 am: |
|
Thanks a lot everyone. I appreciate you guys that have taken the time and effort to help me with long and detailed info. KID VICIOUS...you are right about misinformation...I have seen a lot of it and I do agree with you about Tech 833. I have already realized his expertise. He has never answered any of my questions directly but I have followed his threads already as you have suggested. And, trust me on this...I'm a research freak on anything that I do. If there is an article out there on the Imax or other ants you can rest assured that I have read it. Tech 808 has answered some of my posts and I do trust his experience as well. HOTWIRE...I thank you for all the good info too and I do have a used Workman TVI 2K low pass filter a friend gave me. Somewhere along the line it appears that someone has turned the mic all the way up on my original President Washington. When we tested it at a friends house we had to turn down my D-104 quite a bit. The mike gain on the radio hardly had any effect when turning the knob. I plan on taking it to a well known tech and I will have him check that out. I want to be able to have a little more control on the mike gain at the radio since you mentioned that as a possible TVI cause. HOLLOWPOINT...yes, I just read a few articles concerning the multiple lengths and I am aware of the formula for trimming the coax. But I also agree with you that it probably isn't needed since its only advantage seems to be the correct SWR reading at both ends. Your comment on the choke answers my original question but it also puts the GPK closer in height to my neighbors TV ant. My original fear was that using the GPK would be counterproductive since it would be closer in height to his TV ant and thus it would possibly cause MORE TVI. Then, Tech 808 said ...no problem if I ground everything. Then...in another post of mine called "Galvanized Pipe a No-No?"...Marconi had some good reasons to NOT ground the antenna at ALL. Although...if it's already there a ground will maybe help to KEEP it there. As Kid Vicious points out...when you ask a question in this hobby you get shotgunned with all types of info. I was going to use the Imax without the GPK. My friend uses his without one and his system works super great. I'm not sold on the advantages and extra expense of the Imax GPK other than possible help with TVI but when I saw my neighbor put up that TV ant I figured I would get the GPK. That's when my friend gave me his theory of the possibility of the GPK being counterproductive in this instance. Again...thanks everyone...after all this, I'm still not exactly sure just what I'm going to do with this installation.
silverfox |
Tech833
Moderator
Username: Tech833
Post Number: 1297
Registered: 8-2002
| | Posted on Monday, April 03, 2006 - 11:06 am: |
|
I'm flattered!
I agree that the GPK will not create any additional RFI in you case. I would like to point out that the GPK actually helps most with TVI when your neighbors are below the antenna.
Since your neighbor is 200 feet away, if you run legal power on a non modified radio, there is no way you should cause any problems with the neighbor's TV set. Unless, the TV is defective. The only 'fix' for that is replacing the TV set. |
Silverfox
Junior Member
Username: Silverfox
Post Number: 25
Registered: 3-2006
| | Posted on Monday, April 03, 2006 - 7:03 pm: |
|
Thanks for chiming in 833...I was hoping you would.
silverfox |
Capt205
Member
Username: Capt205
Post Number: 74
Registered: 5-2005
| | Posted on Tuesday, April 04, 2006 - 6:58 pm: |
|
I have my IMAX up 30' to the feed point. There is 175' of rg213 coax buried between station and antenna. I followed the advise found on this site about station and antenna grounding.
I have zero tvi or other types of rf interference with anything in my house or any of the houses next to me.
One of the houses is 16' away from mine....zero problems, and I have asked them all. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1320
Registered: 7-2004
| | Posted on Wednesday, April 05, 2006 - 10:17 am: |
|
Do you have the GPK Capt205? |
Slugo4449
Member
Username: Slugo4449
Post Number: 75
Registered: 7-2004
| | Posted on Thursday, April 06, 2006 - 12:06 am: |
|
I hope you don't live out in a fringe area for TV reception. The stronger the TV signals the less chance of TVI.
I think ALL of the ideas above are great.
73
Marty
KG6QKJ |
