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Post by sfi355 aka Billy Bob on Apr 27, 2021 22:08:52 GMT -5
I believe that I have a 1975 ish P500 Penetrator, I had order all the parts from MFJ and I assembled the antenna. Now tested the antenna. And what I getting is that the antenna is resonating at 30.300 to 32.300 MHz the SWR is 1.5 at each end. At 27 MHZ swr is 3.0 and up. Now the base that I got from MFJ didn’t have any holes drilled so that force me to drill through the metal that is molded at the top of the part, so I can put a bolt all the way through to be able to tie the hair pin element to. I have made the center element longer and I still got the same results. Now I made up a much long hair pin and again I got the same results. Does anyone have a clue what this is?
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Post by 2600 on Apr 28, 2021 0:43:10 GMT -5
Doesn't sound right. Making the main element longer should have moved the resonant frequency down.
Enough to see on your analyzer, anyway.
Doesn't make good sense.
73
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air1
Ratchet Jaw
Posts: 69
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Post by air1 on Apr 28, 2021 8:15:33 GMT -5
On the Hy-gain 500 there is a stud that goes through the side of the bottom insulator. Inside of that insulator the wire from the center of the coax connector connects to that stud. On the out side of the insulator one end of the gamma match rod and the beta rod connect to the stud. The gamma match rod is supported by the two insulators and the other end is attached to the bolt that holds the vertical element to the top of the insulator. The other end of beta rod connects to one of the bolts that holds one the ground plane elements to the bracket. Since all the element sections of the whole antenna are clamped together and not preset as some antennas are that use screws, it's important to make sure they are all the correct length as stated in the manual. If you have a 1975 it should have 3 sections on the ground plane radials and 2 bolts holding them to the bracket. The later Telex hy-gain used 2 elements for the ground plane radials and 1 bolt to hold the ground plane radials to the bracket. Makes no difference except that it was most likely cheaper to produce that way with lees element tubes and bolts. In 1977 they changed the height of the antenna's vertical radiator measurement from 22' 9 1/2" to 22'6" because of the 40 channels being authorized. The center frequency of the band went from channel 12 to 19 so the antenna had to become shorter. Still an antenna analyzer will be a great help.
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Post by sfi355 aka Billy Bob on Apr 28, 2021 21:21:35 GMT -5
So what you are saying from the so-239 center connector goes to the side of the plastic mount where the 2 rods are tied together?
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air1
Ratchet Jaw
Posts: 69
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Post by air1 on Apr 29, 2021 8:39:21 GMT -5
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Post by sfi355 aka Billy Bob on Apr 29, 2021 11:47:58 GMT -5
Thanks for the information. But the manual doesn’t show how it is hooked up inside of the bottom of the black base.
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air1
Ratchet Jaw
Posts: 69
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Post by air1 on Apr 29, 2021 18:16:28 GMT -5
Inside a wire is soldered to the center of the antenna connector and the other end of it has a ring terminal that connects to the stud that goes through the side of the insulator. A bolt could be used also with the head inside. The original wire was a small gauge but something like a 12 gauge wire would allow you to run more power without burning up the wire.
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Post by sfi355 aka Billy Bob on May 4, 2021 11:47:38 GMT -5
I Toke the antenna down, I took the base apart and this time I took the wire from the center of the SO-239 coax connector and hooked it up to the bolt on that sticks out of the side of the Plastic Base, I put the antenna back together and set it up as per the manual and and now the antenna works as it should. SWR at channel 1 is now 1.4 and at channel 40 it is 1.1. Thanks for your help Air1.
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air1
Ratchet Jaw
Posts: 69
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Post by air1 on May 5, 2021 7:53:20 GMT -5
Glad to here you got it going.
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Post by Retro Grouch on Jan 13, 2022 17:20:18 GMT -5
I Toke the antenna down, I took the base apart and this time I took the wire from the center of the SO-239 coax connector and hooked it up to the bolt on that sticks out of the side of the Plastic Base, I put the antenna back together and set it up as per the manual and and now the antenna works as it should. SWR at channel 1 is now 1.4 and at channel 40 it is 1.1. Thanks for your help Air1. Did you happen to measure both the main radiator length and the radial length? Also, did you use top hat rods? |
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Post by sfi355 aka Billy Bob on Jan 22, 2022 19:21:40 GMT -5
I Toke the antenna down, I took the base apart and this time I took the wire from the center of the SO-239 coax connector and hooked it up to the bolt on that sticks out of the side of the Plastic Base, I put the antenna back together and set it up as per the manual and and now the antenna works as it should. SWR at channel 1 is now 1.4 and at channel 40 it is 1.1. Thanks for your help Air1. Did you happen to measure both the main radiator length and the radial length? Also, did you use top hat rods? . My antenna has the 2 bolt holes with 3 pipes to make up 1 radial length of 105 inches long. The main Radiator length was set at 22 feet 4 inches and yes I had all 4 top hats elements on and those were 9 inches long each and set in the same direction of the bottom radial’s and pointed downward I would say at 30 degrees. This antenna was 7 feet off the ground and it was feed with RG-213 at 100 feet of coax at the time of testing. A RigExpert AA-230 Zoom Was the unit that did the antenna/ coax testing. |
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Post by Retro Grouch on Apr 4, 2022 1:13:28 GMT -5
Sorry it took so long to get back to you. The original 1970s Hy-gain Super Penetrator500 & Golden Penetrator (which is exactly the same antenna plus a gold colored "Iridite" (chromate) finish which is not as durable as anodizing) were 22' 9.5" from the bottom of the connector to the top bolt holding the top hat rods, plus four 9.5" long top hat rods.
That original 23ch series was tuned flat at 27.000 for center between 26mhz to 28mhz, and the top hat rods were bent down at a 45° angle, never straight out.
If you were to bend them up so they were straight out horizontal, then it would become a capacity hat and electrically lengthen the radiator to way-too-long.
If you wanted a little lower Q antenna for broader bandwidth and didn't mind losing a needle width or so in performance, then straighten out the top hat rods to flat (horizontal) and shorten the antenna until you get the SWR you want - at whatever frequency you want it.
To get it to tune flat at 27.205 the original Penetrator needs to be shortened 2 inches to 22' 7.5" from bottom of connector to top hat rod bolt, and using 45° downward 9.5" long top hat rods. Also, shorten the radials 1 inch to 8' 8".
If you can slide a Teflon or PVC tube (without side play!) between the radials bracket and the radiator, (resting on the lower Hairpin spacer) instead of using the supplied crappy hard plastic insulator - which inevitably cracks and allows minerals to build up in the crack so when wet and running an amplifier it arcs across - then you should be able to tap 2500w pep without incident.
Happy Antenna Erection.
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Post by sfi355 aka Billy Bob on Aug 28, 2022 14:36:03 GMT -5
I just put up the restored P500 antenna yesterday, all I can say is wow, The receive is 2 s units stronger and my TX is a heck of a lot stronger. There is a HUGH difference Between a Antron A-99 to this P500, 73's
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