Antenna + Rain = SWR drift

[RC286]

I picked up an antenna out of the classifieds for nothing and set it up as my base.
Not sure what it is, there are no markings on it anymore. Was a bit beat up, and after
straigtening out the radials a bit, and the odd couple sections of the radiating element, cleaning all the
joints, assembled with penatrox and sealed with rubber splicing tape on all joints. I put it up on my mast.
The mast is 1 1/4" EMT pipe off my fence, it is about 18' tall. Two ground rods sunk, grounded the mast and the antenna bracket. It is fed with 50ft of Belden RG-8U into my shack. Radio is an old midland 79-892.

The best I can describe the antenna is it is a base loaded 5/8 wave vertical with 3 radials. Total radiator height is about 26' Looks kinda like they hy-gain penetrator, however with 3 radials instead of 4. Same kind of wrap around sleve to anchor the radials.
I know nothing about this antenna, not sure who made it, performace characteristics etc. just got it and threw it up there.

When dry the antenna system SWR is between 1.5:1 and 1.6:1 across the band, however when it gets wet
The SWR drifts up a hair past 2:1.

I have this same issue with my friends super slammer we put up at the lake this summer, Thought maybe water was getting into the loading coil, so we sealed everything up with silicon. It still happens.
Only thing I can think of, is then wet, the water creates RF leakage between the radiator and the grounded
bracket that normally the insulator provides isolation. On his antenna, we siliconed the crap out of that section as well to prevent water from pooling where the radiator passes through the insulator. Still no help.

Is this just a flaw with these antennas? or is there something I am overlooking. Its just annoying that I am
constantly checking my SWR if it is raining, or if there was heavy morning dew. I know the 2:1 SWR probably wont kill the radio, but there is just that paranoia that it will drift up past the critical point one day.

Any suggestions? Or do I just have to live with it?

 

[KC4RAF]

You're right, 2:1 will not kill the radio.

When it rains, all the elements of the antenna becomes wet and thus changes the SWR. Almost all antennas have this down side to rain (and snow). My PDL quad would do the same thing; from a 1.8:1 dry, up to 2.4:1 when wet. Best advise I could give you is; check your SWR at the beginning of your day transmitting, and then forget about it till the next day when you start transmitting again. I actually checked my SWR once before getting on the air that day, and then no more checking till the next day or whenever.
Long post to just say you're ok with the bumped up numbers when it rains...(as long as they aren't way outa sight).

 

[RC286]

Yeah it was kind of a long post to say what I said, I just like to try and devulge as much info as possible.

I figured as much that there would be nothing to remedy it and it makes sence that it would drift.

It was just weird because my first antenna that was made out a mobile antenna on my roof with 3 12awg radials didn't drift at all. Didnt matter if there was rain, snow or ice on it, the SWR stayed right at 1.6:1. Just luck I guess.

 

[WA0CBW]

Is the coax and connector weather proofed where it connects to the antenna?
BB

 

[RC286]

Is the coax and connector weather proofed where it connects to the antenna?
BB

Yup, wrapped up tightly with self sealing rubber splicing tape.

 

[WA0CBW]

You might also make sure you didn't seal up any weep holes. They are there to let any water leak out.
Every antenna will change slightly when wet. Yours seems to be maybe a little more than usual but without seeing the antenna it would be hard to determine why?
BB

 

[RC286]

I think I have narrowed some of my confusion to a wonky SWR meter.

The SWR reading on my Hansen FS-4 meter is about 1.1:1, and if I recall, this meter was accurate
when compared to my Jana meter I have at the lake.

The meter on my Catalyzer JBC-1001-FSC reads almost 2:1.

Gonna have to look into this some more. I went out and checked and cleaned all the coax and ground
connection on the antenna this afternoon. Everything looked fine.

I attached some images. I took a look at the antenna while I was up on the ladder to see if there
were any drain holes. I didn't see one. IIRC the one on my friend super slammer at the lake was on the
lowest section of the vertical radiator, about half way up that section. Didn't see anything like that on mine.

 

[grizwald]

Looks like it might be a Hygain Model 473 CLR-2 antenna the little brother of the penetrator 500 , look on cbtricks.com go to the antenna section should find all the info on it

 

[prcguy]

The OP mentioned its 26ft tall and the CLR-2 is about 19ft tall, unless he's referring to how high its mounted.
prcguy

Looks like it might be a Hygain Model 473 CLR-2 antenna the little brother of the penetrator 500 , look on cbtricks.com go to the antenna section should find all the info on it

 

[RC286]

Hmm, well now I'm doubting my memory. I'm sure I measured the antenna to be between 24-26' (including the loading coil/bracket assembly) but not sure anymore. It very well could have been 19 feet.
Might be time for a protractor and some trigonometry to find out for sure.

The top of the mast is 17-18' from grade. The antenna "looks" taller than the mast, though those kind of viewing angles can be deceiving.

In the mean time, its time to figure out if my SWR meter is wonky or not. I tried the "run the meter backwards to check for ballance" trick, and i get a 2.5:1 reading, so if this trick is as true as I have heard, then my meter is at the very least out of balance. time to check the integrity of the diode, resistors and caps.

 

[grizwald]

The CLR-2 is 19 feet 10 in overall height the bottom radials are 103 1/4 inches long , do not put a lot of power to the antennas you will burn up the copper printer board inside the antenna , if you want more info on this antenna go to CB Trick.com

 

[RC286]

I did some reading on the clr2. seems there was two versions. the hy-gain and a radioshack model. seems one had a wire wound loading coil and the other was a foil wafer. the latter being the one that doesnt handle power. no idea which i have.

 

[JayMojave]

Hello RC286: Yes that's what I a thinking also. Your antenna looks like the radio shack version to me.

How ever you can modify that antenna with the same "hairpin" matching system that the Hy-Gain Penetrator has. I have modified these older CLR-2 antennas removing the matching coil in the bottom insulator to have the hairpin matching wires now making the CLR-2 take way more power. 12 Gauge house wire will also work, will need a antenna analyzer to tune it all in. The Hy-Gain manual on the Penetrator 500 will be a help.

http://www.hy-gain.com/pdffiles/SPT-500.pdf

Jay in the Mojave

 

[km4fcz]

Hygain Super Penetrator

As to high swr when this antenna gets wet, I found the problem. Mounted on a 10 foot pipe and with a step
ladder used to get to the bottom of the antenna, I started spraying water at the black base and coax connector,( moved the ladder every time) and rechecked the swr with no change (1.2 to 1). Went back and sprayed the insulator at the ground radials,( just enough to saturate that area) and the swr went up to nearly
a 2 to 1 swr. Tried several times (dry to wet), same results. So I know why it happens, but I dont know the
remedy. May be someone does?

 

[samiam75]

As to high swr when this antenna gets wet, I found the problem. Mounted on a 10 foot pipe and with a step
ladder used to get to the bottom of the antenna, I started spraying water at the black base and coax connector,( moved the ladder every time) and rechecked the swr with no change (1.2 to 1). Went back and sprayed the insulator at the ground radials,( just enough to saturate that area) and the swr went up to nearly
a 2 to 1 swr. Tried several times (dry to wet), same results. So I know why it happens, but I dont know the
remedy. May be someone does?

I believe I have the same antenna. Mine is the version with the cheap wafer style matching coil in the base (i beleive the radio shack version). I too have had frustration with the rain affecting my SWR. I have taken the whole antenna apart, sealed all joints and the base, cleaned connections to the wafer coil, sealed coax, etc...

Finally, I took a piece of pvc pond liner material that I had laying around and made a rain hat of sorts a couple feet above the area where the ground plane is insulated from the vertical. It basically forms a cone shaped hat over this area, attached to the vertical and then draped down the radials.

This seems to have help me quite a bit by keeping the majority of the water diverted away from the insulator at the ground radials.

after 2 years running like this, i have noticed the problem start to creep back up, so I am thinking my rain hat has started leaking so I plan to bring it back down and make a better version to last longer. I am guessing that whatever you use needs to be non metallic to not affect the performance of the antenna.

Let us know if you come up with a better trick.

 

[KC2GIU]

Finally, I took a piece of pvc pond liner material that I had laying around and made a rain hat of sorts a couple feet above the area where the ground plane is insulated from the vertical. It basically forms a cone shaped hat over this area, attached to the vertical and then draped down the radials.

This seems to have help me quite a bit by keeping the majority of the water diverted away from the insulator at the ground radials.

Let us know if you come up with a better trick.

This is almost the same story of DishTV reception in the rain. Basically the reception is almost nothing and is useless. Now, there are the rain hats and rain brellas people use with fair to good success.

Good thinking for doing this with radio antenna gear too.

Some of the older CD (Civil Defense) antennas used PVC over the entire length of the antenna whip with an umbrella hat over the radials, but not the entire length of the radials. This is the same for Marine Antennas.

BTW, it does help a bunch to ground the radio. Read the radio manual to do this because there could be more than one ground for a radio. Some radios have a PCB ground that is an offset voltage from common ground. NEVER ground to the offset ground anywhere on a radio, you'll burn things up. Chassis ground usually works best.

 

[prcguy]

Its completely different than Dish TV reception, that is pure attenuation due to water absorption in the 12GHz range of the satellite downlink. Even with occasional rain fade the satellite TV providers usually deliver a perfect picture at least 99.9% of the time with 99.97% being a goal, that's an industry standard. If not then your dish has moved eating up some of your rain fade margin and needs realignment.

Grounding the radio or the antenna will have no effect on the OPs problem.
prcguy

This is almost the same story of DishTV reception in the rain. Basically the reception is almost nothing and is useless. Now, there are the rain hats and rain brellas people use with fair to good success.

Good thinking for doing this with radio antenna gear too.

Some of the older CD (Civil Defense) antennas used PVC over the entire length of the antenna whip with an umbrella hat over the radials, but not the entire length of the radials. This is the same for Marine Antennas.

BTW, it does help a bunch to ground the radio. Read the radio manual to do this because there could be more than one ground for a radio. Some radios have a PCB ground that is an offset voltage from common ground. NEVER ground to the offset ground anywhere on a radio, you'll burn things up. Chassis ground usually works best.

 

[KC2GIU]

Its completely different than Dish TV reception, that is pure attenuation due to water absorption in the 12GHz range of the satellite downlink. Even with occasional rain fade the satellite TV providers usually deliver a perfect picture at least 99.9% of the time with 99.97% being a goal, that's an industry standard. If not then your dish has moved eating up some of your rain fade margin and needs realignment.

Grounding the radio or the antenna will have no effect on the OPs problem.
prcguy

For DishTV reception, I agree, but it's not 99%, more like 80 at best. For DishTV satellite internet needs the hood or a sock. I know because I live with this everyday!

Grounding the radio will improve SWR readings. Been there and done that on many occasions. Many home base setups are using mobile radios, thus grounding via the AC wall-outlet doesn't reach the radio unless the person manually and purposely grounds to the third prong or to a metal water pipe or to a direct ground connection to the earth.

 

[K5MPH]

I think that these antennas were known for high SWR's back in their day due to water/rain getting inside but dont remember if their ever was a fix......