Base Antenna Help

[225inthegreatlakes]

I have a Penetrator 500 base antenna that I am trying to get a good swr for 27 mhz. I put the antenna together just like it says to do with the directions but when I check it with my antenna analyzer it has a 1.1 swr on 28 mhz. But a 2.5 or 3.0 swr on 27 mhz.so I moved the top element of the antenna up and down with no results any suggestions?

 

[Marconi]

I believe they made two different Penetrator antennas. Can you describe the one you have.

One shows a length of 193.125" length and the other shows 196".

I got my doc's from someone else and he noted on the documents that one was for 23 channel and the other was for 40 channel. The way he has it marked the shorter one is marked 23 channel version. I would figure that the center of 23 channels would require a bit longer element, so I'm not sure he knew what he was talking about.

They both show different kinds of hardware and they may be matched differently, but not sure on the matching thing.

The only thing I know is that there are two different sets of docs for this model 500 from Hy-Gain.

 

[225inthegreatlakes]

mine says its 196" or 497.8cm from top of the antenna to the top of the first vertical element.

 

[Master Chief]

Hy-Gain came out with the Super Colinear in 1962. It was a flop, because it broke off at the base, it was single point mount for the vertical element.

Then Hy-Gain came out with the CLR II. Mid 1960's I believe. It had a two point mount that would stand up to bad weather, but had a Mickey Mouse cheap bad impedance matching device on a circuit board, located in the bottom insulator. Any power would burn out the etched coil on a circuit board coil.

Then Hy-Gain came out with the Penetrator 500 around early 1970's. It was advertised to take 1500 watts.

In 1980 or so, Telex bought out Hy-Gain. The Super Penetrator 500 was then sold. It had a gold like anodized finish. But Telex cheapen the design of the orginal Penetrator. Hy-Gain Penetrator's have two 1/4" inch bolts attaching the ground radials, and the Telex has one 1/4" bolt. Same antenna, but the Telex antenna was not as beefey. Worked the same.

Hy-Gain came out with 3 each Penetrator 500 antennas.

1 the first one was 259 inches long for the 23 channel radios
2 & 3 where 256 3/8 inches long, for the 40 channel radios.

There was just vertical element length differences, for the longer lengths. You can tell it you have a old orginal 23 channel P500, the bottom vertical element is 1 1/4 inches in dia, but is 77 inches long, the other 40 channel ones where 71 inches long. You simply shorten a 259 inch P500 to 256 3/8 inches, if you want. The Ground Plane Radials and tuning wires stay the same.

Telex took over Hy-gain in 1979 or something like that. Telex P500 antennas have only one bolt holding the ground plane radials inside the mounting Clam Shell Bracket.

Telex is the one that made the Golded Penetrator 500, that had a cheap gold anaodized finish to it that would come off in a few years of use.

Yes all the P500 where called part number "Order 500"

Hy-Gain ran into problems with the tollerances of the Aluminum Tubing "Wall Thickness". Tubing .058 inches wall thickness did not always come .058, it get to be thicker not allowing the tubing to "Telescope" inside each other. So they came up with the Reduced Swaging the ends of the tubing, to allow the next smaller size to fit into the reduced swaged ends. This allowed the element to be strong and light, being resilant.

Most all the tubing used by Hy-Gain from what I can see was good material.

Jay

I thought you might enjoy this little bit of history.

 

[Master Chief]

As far as answering your question..... This antenna was designed for the CB band. The longer antenna would have been centered around 27.105 (23 channel) and the later antenna around 27.205.

As we see from Jay above, the only difference was in the length of the main element.

You analyzer is telling us the antenna is too short. I can only assume that you have all the right lengths of tubing. The only part you can tune on this antenna is the main element. Double check all tubing lengths.

The next issue would be (what I call) the hairpin. Is this part original? If it has been altered, then we have a problem Houston! This hairpin replaced the original printed circuit boards that Jay spoke about above. It needs to be the correct size to operate correctly!

Make sure all the elements and the hairpin are making a good electrical connection! I highly recommend using 3M plastic ScotchBrite pads to clean the joints! You can get the industrial ones at Home Depot. Steel wool is BAD!

I did a re-install of an I-10K for Snoop Dog's neighbor in Long Beach, CA. He swore up and down that all the measurements were right on. When I couldn't get it to match up, I took the antenna down and found that the top element was 10" too short. Double check all your measurements!

Also, try another piece of coax. Yours might be bad causing the bad reading.

 

[225inthegreatlakes]

Thanks for all the history on the antenna etc.I am sure I put all the elements together correctly,after all I am getting a good swr for 28 mhz. although that is not what we want ,Is there anyway this antenna was modified before I bought it or do you think the antenna needs cleaning if it is put together correctly?

 

[Master Chief]

It is always possible that the antenna was modified. Hopefully Jay will chime in here with the correct measurement of the "hairpin".

Again, the analyzer is telling us the antenna is too short. If there is excessive corrosion, the top element may be "insulated" from the rest of the antenna, although this is not very likely! Since it is working on 28MHz, it leads me to believe that the problem is something other than corrosion. Have you tried a different piece of coax yet?

If I was having this problem, I'd tear it all apart, measure each piece for correct length, clean, and reassemble. I'd also make sure I cleaned the hardware that connects the hairpin to the feedpoint and the element!

 

[Marconi]

225, the feeder on this antenna consist of two different wire, you have both?

 

[smalltiredart]

On my Penetrator I could not get any better match than 1.4 on the MFJ. I removed the factor Beta match ( the thing that looks like a water bottle holder hair pin thingy ) and constructed an adjustable matching circuit similar to what Jay did on the 10K. After that my match is 1.0 swr, 49 ohm , X = 0 with 99% antenna efficentcy.

 

[225inthegreatlakes]

ok I went through and checked all the measurements and they are all correct length m2 with expose of 52 1/8 m3 with expose of 49 3/8 m4 with expose of 44 1/2 and top radial assy of 50"
and the ground plane elements are r2 expose 30" and r3 exposed at 50. I did noticed it looked like one of the ground plane elements broke before it was a inch or so short so i just made it longer so it would be the right length if the ground plane elements have anything to do with the swr. I also noticed today it looked like one of those wires on the bottom of the antenna that looks like a coat hanger connected to one of the ground elements bolt to another bolt where the other coat hanger thing connects was broken before and the wire rebent to connect to the bolt. but everything else looks ok. still no luck with the swr. I took the top radial and lengthing it and shorten it but was unable to get a good swr for 27 mhz.

 

[Master Chief]

After that my match is 1.0 swr, 49 ohm , X = 0 with 99% antenna efficiency.

How were you able to measure the efficiency of your antenna? Since approx 12" of the main radiator is inside the base clamp (ground), how did you compensate for the losses there?

Both the Avanti Sigma 5/8 and I-10K use an elevated feed to help minimize losses and I don't believe either of these two antennas are 99% efficient.

If I remember correctly (and I do), the I-10K was a significant upgrade over the original Mastadon 5000 concept which was nothing more than a Penetrator with an improved feed system like you used.

 

[Marconi]

Master Chief, undoubtedly he would have had to build a whole new base setup as well as the tuner and just use the stinger. He would even have to redesign something to hold the ground radials.

You're exactly right he could not have just simply built a tuner like Jay and added to the antenna. Sounds like someone's been partyin’ too much. I sure would like to see a picture of that booger since I'm from Missouri.

 

[smalltiredart]

After that my match is 1.0 swr, 49 ohm , X = 0 with 99% antenna efficiency.

How were you able to measure the efficiency of your antenna? Since approx 12" of the main radiator is inside the base clamp (ground), how did you compensate for the losses there?

I'm just going by what readings I got off my MFJ 259B. In advanced mode it shows match efficency. I did not componsate for loss, however the antenna was up on my tower when I tested it.

If I remember correctly (and I do), the I-10K was a significant upgrade over the original Mastadon 5000 concept which was nothing more than a Penetrator with an improved feed system like you used.

Thats basically what I did is created a Mastadon 5000. Jay would not do it for me.

 

[smalltiredart]

After that my match is 1.0 swr, 49 ohm , X = 0 with 99% antenna efficiency.

How were you able to measure the efficiency of your antenna? Since approx 12" of the main radiator is inside the base clamp (ground), how did you compensate for the losses there?

I was just going by my MFJ 259B in advanced mode, it reads match efficency. I did not compensate for any loss. The antenna was on my tower when I tested it.

 

[smalltiredart]

Master Chief, undoubtedly he would have had to build a whole new base setup as well as the tuner and just use the stinger. He would even have to redesign something to hold the ground radials.

You're exactly right he could not have just simply built a tuner like Jay and added to the antenna. Sounds like someone's been partyin’ too much. I sure would like to see a picture of that booger since I'm from Missouri.

I just took a piece of 3/8 alum. tube, with a piece solid alum. 3/8 o.d stock and bent a U shape. Attached it to the same points that the stock Beta match attached to. The top of the U slides on the solid stock and clamps with worm gear clamps. When on the MFJ and I slid the device up and down it gave me a different ohm and swr reading.

I have no clue what you are talking about re-designing the ground radial holder ? It uses the same one it always has.