SWR Question

[Panarobo]

Just installed my Tram 1489 SWR was 1.1 until i raised it to the top of the mast approximately 10 foot above my roof now its 1.3 to 1.4 but when it rains in drops back to 1.1 any ideas why? I installed 2 ground rod about 18 feet apart can only drive them in about 4 1/2 feet before hitting bedrock. The ground rods, mast ground and CB ground all go to a ground bar. Each is a separate run.

Tram 1498
50 ft MPD Digital RG8U-UHF
Modded Robyn SB-520
Stock Uniden Washington

[295 antenna]

Where was it when you got the 1.1 match ? cause right now it sounds like your getting reflection from somewhere

[Panarobo]

I have an eave mount.The 1.1 was about 1 foot above the roof sitting on the mount now I'm about 10 feet above the roof. My neighbor's house is 15 feet away but the base of the antenna clears their roof peak by at least 2 feet. Nothing else is even close.
Our houses have shingled roofs mine is a single story my neighbor's is a 1 1/2 story, basically a single story with a walk-in attic.

[295 antenna]

Im not familiar with that antenna. Can you adjust it ?

[Panarobo]

Not without bringing it back down where I had the swr at 1:1

[Blue Ox2]

Just installed my Tram 1489 SWR was 1.1 until i raised it to the top of the mast approximately 10 foot above my roof now its 1.3 to 1.4 but when it rains in drops back to 1.1 any ideas why? I installed 2 ground rod about 18 feet apart can only drive them in about 4 1/2 feet before hitting bedrock. The ground rods, mast ground and CB ground all go to a ground bar. Each is a separate run.

Tram 1498
50 ft MPD Digital RG8U-UHF
Modded Robyn SB-520
Stock Uniden Washington

Yes, there are tuning rings on that antenna so you can work it in closer on your SWR if you desire.
If it isn't too much difficulty bringing it back down, and up, and down.

That SWR really isn't too bad, considering.
If you need it tighter, yes, bring it on down, make the adjustments and test again.

JMHO
73,

Mike

[Panarobo]

If we get warmer weather I will tinker with it. I'm more curious why the SWR goes lower when it rains

[Blue Ox2]

If we get warmer weather I will tinker with it. I'm more curious why the SWR goes lower when it rains

Rain does cause some effects to SWR and it can be caused through the coax connection, the additional ground wires you have, the height, and wind effects as well.

You can google your questions and see a bunch of ideas about your issue.

73,

Mike

[Panarobo]

Thanks everyone for the help and suggestions.

[MDYoungblood]

That antenna is similar to the Antron A99, the SWR might be changing because of the added coax used to increase the height. Not knowing the meter used the difference might be related to CMC, (common mode current), trace RF on the coax. If the antenna isn't hard to take back down and adjust, I would do that first. You could make a choke just under the feedpoint, a common design is 5 wraps of coax about 4 1/2" in diameter. Here is an image of what I'm talking about,

Grounds are important too, your mast/antenna ground sounds fine, the antenna is shunted do bleed off static build up but you didn't say you added a coaxial ground to it. Also the radio, PS if used, and the SWR meter if it is an external type should be grounded.
If you use the search box for the forum, you can find all this info.

3's

Greg

[Panarobo]

The only thing not grounded to the ground bar is the external SWR meter. I'll try that soon. Ohio's weather is preventing me from adjusting the antenna. I'm running barefoot, Robyn SB 520D modded/tuned (auction find) and a Uniden Washington factory stock. I only have a single 4 foot loop of coax inside.
I'm using an Astatic PDC1 SWR meter now. The SWR on my Para Dynamics PDC600 isn't working, another auction item.
How do you ground the coax?

[MDYoungblood]

I have lightning arrestor/surge suppressor's inline on my coax just before the coax enters the house and they are on a separate ground rod system.

3's

Greg