Phelps Dodge Antenna Rebuild

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TvRadioGuy
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Phelps Dodge Antenna Rebuild

Post by TvRadioGuy » Mon Sep 12, 2016 10:52 am

We recently acquired a Philips Dodge antenna. We where told it was a Jampro after contacting Jampro They said it was not theirs. After some research we now know what the antenna is. Its Phelps Dodge does anyone know where I can get rebuild parts for this antenna would like to changing all o rings also any Tuning Tips Its on the upper band. We have to move it back a few numbers back.

Thanks

rich wood
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Re: Phelps Dodge Antenna Rebuild

Post by rich wood » Mon Sep 12, 2016 1:34 pm

I bet that antenna is 30+ years old, and spare parts will be difficult to find at best. As far as tuning, those antennas were narrow band devices and it may not move in frequency at all. I would assemble it on saw horses and sweep it, if possible, or at least hook up an exciter and see what the reflected is at the freq it is supposed to be on. Send a pic, the tuning may be at the input section and or at the elements themselves.

W2XJ
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Re: Phelps Dodge Antenna Rebuild

Post by W2XJ » Mon Sep 12, 2016 2:06 pm

I wouldn't even try to reuse it.

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Deep Thought
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Re: Phelps Dodge Antenna Rebuild

Post by Deep Thought » Mon Sep 12, 2016 2:08 pm

If it is a multi-bay antenna you'll also need to change the inter-bay hardline in order to change the frequency it is tuned to, which pretty much makes the whole project a non-starter.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Shane
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Re: Phelps Dodge Antenna Rebuild

Post by Shane » Tue Sep 13, 2016 11:48 am

It might have some value if you're into history. Antennas apparently weren't exactly a major focus of PD. They bought some companies that made various types of antennas, recombined them and apparently the whole multi-billion dollar outfit was sold in a friendly takeover in 2007.

I would highly doubt they have any parts. Some of the middle companies included Cablewave and Celwave. (The word "Cablewave" has become permanently associated with various cuss words in some broadcast engineering circles.)

My older brother worked for the CPC division of Phelps Dodge (CPC was formed independently, then acquired by PD in 1962) as an antenna tester in the late 60s. It was a pretty small division as I recall: the whole factory closed down once a year for two weeks and that was your vacation. I believe he was the only antenna tester they had at the time. I also believe they didn't make FM broadcast antennas at that plant.

Just a little history for your edification.
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ChuckG
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Re: Phelps Dodge Antenna Rebuild

Post by ChuckG » Tue Sep 13, 2016 7:06 pm

Rich is right about the PD antenna. It's old, there are no parts and they were very narrow even when they were in top condition.
I had the joy of maintaining a 12-bay PD. There was a three-slug tuning section @ the antenna input that matched it pretty well until it rained or snowed. The time has come to move on.
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Re: Phelps Dodge Antenna Rebuild

Post by Kelly » Wed Sep 14, 2016 7:44 pm

The only value of a Phelps Dodge antenna would be for scrap copper.
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TvRadioGuy
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Re: Phelps Dodge Antenna Rebuild

Post by TvRadioGuy » Mon Oct 03, 2016 8:12 pm

Thanks for all your replies. Unfortunately, scrapping this antenna would be throwing away dollars. After searching a very long time this was the antenna that was found that is in decent shape and complete and not over priced with all of the mounting hardware to the tower. There is no big budget here and its a project for a small market station; with that said, we are trying to make it work for now and later on when the time is right there will be a new antenna purchased. Its at the upper part of the band and the frequency we need it is not to far back from the tune frequency. We are just trying to get ideas that will help us, and help our learning curb about older antennas. I inspected the antenna and it's solid. I Just got in the seals. I will carefully clean the inner bay lines I don't see where to post a pic of the antenna. This is a 4 bay antenna system it does come with a matching or tuning stub with 4 sections to adjust that goes at the bottom of the 4th bay then the transmission line attaches to it.

Thanks

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Deep Thought
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Re: Phelps Dodge Antenna Rebuild

Post by Deep Thought » Tue Oct 04, 2016 11:13 am

TvRadioGuy wrote:This is a 4 bay antenna system it does come with a matching or tuning stub with 4 sections to adjust that goes at the bottom of the 4th bay then the transmission line attaches to it.
TvRadioGuy wrote:We have to move it back a few numbers back.
Deep Thought wrote:If it is a multi-bay antenna you'll also need to change the inter-bay hardline in order to change the frequency it is tuned to, which pretty much makes the whole project a non-starter.
How many "numbers" does it have to be moved? Who is going to be doing the adjusting? What is the station's ERP?
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

TvRadioGuy
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Re: Phelps Dodge Antenna Rebuild

Post by TvRadioGuy » Wed Oct 05, 2016 9:27 am

This a class A freq Not to far Back 2 whole Chanel's. I have done allot of engineering experience. I have a Gen Operator License - Back in the day its FCC First Class. In this business there is always a new thing to learn. Still learning about antennas even though I am quit familiar with Fm broadcast and TV broadcast. Also have another consulting engineer that expertise is transmitter maintenance. I always like to get other opinions. Thanks for your feed back. Deep Thought , On station details prefer not to discuss on here. Can contact you via email or via telephone.

Thanks

level42
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Re: Phelps Dodge Antenna Rebuild

Post by level42 » Fri Oct 07, 2016 7:33 am

If you'd like to get other opinions, here's one:

Take the antenna to the scrap yard, get the money for the metal, and put that towards a new antenna.

Seriously, this thing isn't worth messing with. It's not designed to change frequencies, and these never were great antennas, even when new.

Depending on how much power you need to put into the antenna, something like this would probably work fine and will provide much better performance and should be within reach financially of any class A station.

http://swr-rf.com/files/Download/FMECPLUS.pdf

ChuckG
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Re: Phelps Dodge Antenna Rebuild

Post by ChuckG » Fri Oct 07, 2016 9:08 pm

Assuming that antenna isn't a power divider design with 50 ohm bays and IIRC it isn't, you could certainly try adjusting the input matching section. You really need to lengthen the elements to get the reactance right, adjust the bay feed points to get the resistance correct and bump the inner bay sections slightly, but you can't adjust any of it on that antenna without some serious machine work and it is a very, very narrow design.
Set it on some sawhorses, feed an exciter in though a bird wattmeter, or better yet find an impedance bridge, adjust the matcher and see what you get. You probably won't like the results, an already twitchy design will be made worse not better, but it might at least run on sunny days.
I wouldn't stick a nickel into rebuilding it, run it until they can afford a replacement and not a day longer- they'd be better served by putting those nickels towards almost anything else. *cough* not Shiveley in that power range *cough* Good luck.
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Deep Thought
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Re: Phelps Dodge Antenna Rebuild

Post by Deep Thought » Fri Oct 07, 2016 9:53 pm

ChuckG wrote:You probably won't like the results, an already twitchy design will be made worse not better, but it might at least run on sunny days.
On sunny days within a 30° temp range from the day you tuned it.

As noted above, you can probably get enough in scrap to buy a SWR or Nicom and maybe have some money left, as well as some hair.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

vacuum tube
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Re: Phelps Dodge Antenna Rebuild

Post by vacuum tube » Sun Oct 09, 2016 6:37 am

I suggest you listen to the good advise you have been given. In my opinion you will save more money by installing a new Nicom broadband BKG 77-4 rather than trying to use what you have. It's a no brainer in my book. I would never install a 30+ year old antenna that may or may not work well when you can buy a new one for around 4k. This sounds like the project that will save us a thousand dollars even if it costs us 5 thousand more.

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Jim Sofonia
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Re: Phelps Dodge Antenna Rebuild

Post by Jim Sofonia » Tue Oct 11, 2016 5:25 pm

You could try to re-sell it to a station on channel perhaps as a stand by and recover some of your original investment. They wouldn't have to invest much to get in service.
Don't feel too bad about spending money on a bad buy. We have all done it, especially on used or e-bay equipment.

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