Combining two AMs at one site

AM Radio discussion. Directional arrays are FUN!
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KPJL FM
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Re: Combining two AMs at one site

Post by KPJL FM » Wed Nov 02, 2016 7:57 am

What Tom said.
I would think getting three times the cost of moving/combining for the land at the original site would be a good start. There's always cost over-runs, and you want to be sure the *new* owners are serious about making this happen.
This assumes the move to the combined site does not restrict coverage. Sux to lose listeners because you're no where near them anymore.
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grich
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Re: Combining two AMs at one site

Post by grich » Wed Nov 02, 2016 12:12 pm

Lee_Wheeler wrote:I did an interesting one a few years ago where we moved a DA on 1550 into the space between the towers on a DA that was on 680.
Did you make sure the guy mowing the grass can't take out the new towers like he did on the end tower of the 680 array? :mrgreen:

W2XJ
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Re: Combining two AMs at one site

Post by W2XJ » Wed Nov 02, 2016 2:54 pm

1520 and 550 in Buffalo have been combined in the same DA for many decades. 550 is a 4 tower parallelogram and 1520 is a three tower inline that uses two of the 550 towers with an additional one between them.

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Re: Combining two AMs at one site

Post by NECRAT » Wed Nov 02, 2016 4:58 pm

W2XJ wrote:1520 and 550 in Buffalo have been combined in the same DA for many decades. 550 is a 4 tower parallelogram and 1520 is a three tower inline that uses two of the 550 towers with an additional one between them.
1520 only uses one of the four towers in it's pattern. It has two separate towers.
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Re: Combining two AMs at one site

Post by Lee_Wheeler » Wed Nov 02, 2016 10:47 pm

grich wrote:Did you make sure the guy mowing the grass can't take out the new towers like he did on the end tower of the 680 array? :mrgreen:
This time we built fences off of the ends of the anchor points. As far as I know they still bale the hay though - a few hundred dollars a year to the beer fund. :D

It was fun dropping the other towers:

[youtube]https://www.youtube.com/watch?v=R13WJaU-jJk[/youtube]

[youtube]https://www.youtube.com/watch?v=dlwBUuRkKuU[/youtube]

I have another one somewhere that was from a flip camera on a tripod at the tower base - the camera survived.

...Lee

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Re: Combining two AMs at one site

Post by w4cl » Thu Nov 03, 2016 1:52 pm

I diplexed two stations with folded dipoles on the same tower back in the early 80's. FCC had to scratch their heads on that one but they licensed it.

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Re: Combining two AMs at one site

Post by Shane » Thu Nov 03, 2016 5:06 pm

Lee_Wheeler wrote:It was fun dropping the other towers:...
that was a 5-tower in-line wasn't it? (Old 1550 site)

I usually made that drive through on 29 and always wondered where that site was. Finally saw it when leaving town on 36 East instead, way off to the southwest. (2003 I think)

Much later a co-worker noticed the new towers at the 680 site (I haven't been down there yet) and asked me what I knew about them, which at that moment was nothing. A little research ferreted out what had taken place.

Are the 680 feed lines still above ground and open wire (at least I thought they were open wire)? I worked for a different station with these and other out-of-town engineers would cuss 'em but the guy who immediately preceded us (who was only there about 2 years before he died) always said they were the best and that we would really appreciate the bandwidth come IBOC/IBAC whatever it was going to be when we didn't know yet in 1993.

Don't know if he was proven right or not as I left before the digital era finally began. But I believe the open wire feeds are still there.
Mike Shane, CBRE
---Omaha---

Lee_Wheeler
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Re: Combining two AMs at one site

Post by Lee_Wheeler » Thu Nov 03, 2016 6:39 pm

1550 was the array to the South-East of town and it was in horrible shape. They blew a capacitor in one of the ATUs and it took me all day with a chain saw to get to the door on the tuning unit to get in and fix it. As soon as I opened the door it fell off of the hinges. 1550 took a hit in coverage with the move but it wasn't the end of the world and the array actually works now. When we first installed the new 1550 phasor it dealt me fits. It was all tuned up and but two days later the towers would be out by 50% in some cases. I'd retune it back to licensed parameters and then things would repeat a few days later. I finally bought a "mirror on a stick" at Advance Auto Parts and found a big drill shaving laying up against one of the coils back where it couldn't be seen. Once I picked out Kurt Gorman's fabrication residue it was real stable from then on.

We buried the lines for everything - 50 ohms! Three of us spent a solid 2 weeks patching the radials back together and tacking in ground screen after the trencher but it was amazing that the WWII vintage radials were in really good shape. The only other place I had encountered open transmission lines like that was at KFAB of all places. The KFAB setup was in way better shape though when I saw it. There were places on 680 where the center conductor was drooping well outside of the wire box that made up the outer conductors in between poles. As I recall the KFAB setup actually had the tower lighting running on the outer conductors which was slick.

We were cleaning out a bunch of crap that had accumulated over the years and I ran across a telegram from the War Department that gave the station special dispensation to buy the steel and copper to build the site. I guess during WWII you couldn't buy strategic materials without that permission.

...Lee

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Re: Combining two AMs at one site

Post by grich » Fri Nov 04, 2016 9:30 am

Lee_Wheeler wrote:...We were cleaning out a bunch of crap that had accumulated over the years and I ran across a telegram from the War Department that gave the station special dispensation to buy the steel and copper to build the site. I guess during WWII you couldn't buy strategic materials without that permission...
I believe my mentor at NWMSU, Warren Stucki, worked at KFEQ back in the day. He's living just up the road in Savannah.

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Shane
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Re: Combining two AMs at one site

Post by Shane » Sat Nov 05, 2016 9:52 pm

I really meant to say southeast! It's difficult for me to mix up north and south but for some reason east and west are easy to confuse. (Except for one place in New York State where two highways run along together about a mile and you are going south on one and north on the other at the same time.)

Concerning KFAB, last I knew they were still open wire - I should drive by one of these first days. The lighting, as I recall, ran below the transmission line (which was actually coaxial in that there were/are two parallel wires that were the center conductor surrounded by four wires in a box) up to 1/4 wave from the towers and then shunted over to a separate set of supports and so were isolated from the tower by means of a 1/4 wave stub also on those supports.

The bad thing about the open wire was/is that it accumulates ice, which used to drive the MagniPhase in the Continental nuts. Switching to the backup RCA usually cleaned things up a bit, but I later found out that it too had a MagniPhase installed in it that had simply quit working! Explaining why the RCA would stay on even if you terminated it in a pickle barrel.

Anyway, way to design around the problem with 1550!
Mike Shane, CBRE
---Omaha---

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