Combining two AMs at one site

AM Radio discussion. Directional arrays are FUN!
bmoede
Posts: 1
Joined: Thu Oct 27, 2016 10:55 am

Combining two AMs at one site

Post by bmoede » Thu Oct 27, 2016 11:23 am

Just staring to look at If we can move our 1kw non-D AM to our 5 tower 5kw am site. Any thoughts about how to begin evaluation the possibility of this?

COMMENG
Posts: 95
Joined: Wed Dec 18, 2013 4:30 pm
Location: Midwest

Re: Combining two AMs at one site

Post by COMMENG » Thu Oct 27, 2016 11:38 am

Just staring to look at If we can move our 1kw non-D AM to our 5 tower 5kw am site. Any thoughts about how to begin evaluation the possibility of this?
What is your background and experience in BC engineering?

Undoubtedly, the 5kW 5 tower site is Directional.

If your station is licensed for a 1kW non-D AM, how could you possibly duplex a non-D AM transmitter into a Directional site?

COMMENG

User avatar
kkiddkkidd
Posts: 550
Joined: Mon Dec 03, 2007 11:13 am
Location: Lawrenceburg, TN

Re: Combining two AMs at one site

Post by kkiddkkidd » Thu Oct 27, 2016 12:05 pm

COMMENG wrote:
What is your background and experience in BC engineering? Undoubtedly, the 5kW 5 tower site is Directional. If your station is licensed for a 1kW non-D AM, how could you possibly duplex a non-D AM transmitter into a Directional site?

COMMENG
Pray do tell why you can't duplex a ND onto a DA. There are lots of them around.
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

User avatar
kkiddkkidd
Posts: 550
Joined: Mon Dec 03, 2007 11:13 am
Location: Lawrenceburg, TN

Re: Combining two AMs at one site

Post by kkiddkkidd » Thu Oct 27, 2016 12:22 pm

bmoede wrote:Just staring to look at If we can move our 1kw non-D AM to our 5 tower 5kw am site. Any thoughts about how to begin evaluation the possibility of this?
A very simplistic answer to a very involved project is...

The first thing that I would do is contact a good consulting engineer for technical and budgetary info. Some hang out here.

Then get an equipment list to a DA vendor for budgetary estimate.

If you haven't lost your breath by that point, get the engineering done, the equipment built and build it. This all assuming that the ND is eligible to move to the other site. This would be determined by the consulting engineer.

Regards,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

User avatar
Deep Thought
Posts: 3208
Joined: Thu Mar 20, 2008 9:23 am
Location: La Grange, IL
Contact:

Re: Combining two AMs at one site

Post by Deep Thought » Thu Oct 27, 2016 12:28 pm

Welcome to the site.

I do this all the time. In fact, I just came back from a road trip setting up a new nighttime where two three tower DA stations use the same towers, one of which is (now) a DA-2. I added two NDs to a four tower DA in Las Vegas last fall and have one site in Minnesota with *four* stations running DA-2 on various combinations of seven towers and another in Reno with three two tower DA-Ns and a class-C ND. It is unusual for me to have a project which involves only one station these days. :lol:

If you would like me to take a quick look at your situation PM me the station call letters and I'll give you an idea of how complicated it would be. Some are fairly easy and relatively inexpensive while others can involve some magic if the frequency spacing is close. If you don't want to use the PM system here you can send me the details at ve@muellerbroadcastdesign.com. Cost: $0.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

User avatar
davedybas
Posts: 209
Joined: Wed Dec 19, 2007 8:16 pm
Location: Buffalo Grove, IL
Contact:

Re: Combining two AMs at one site

Post by davedybas » Thu Oct 27, 2016 3:34 pm

What you want to do is called "Diplexing" and it's done regularly. The first thing to consider is the frequencies of the two stations involved. If they are closer than 100 Khz apart in frequency, there could be problems keep one stations signal out of the others transmitter. But if you have enough separation in frequency then the project can be done.

Filters will have to be installed in the AntennaTuning Units of the Directional AM station, as well as the ATU of the Non-Directional station. This is not a simple job and does require a reputable broadcast consulting engineer...like Mr. Deep Thought who has posted on this thread.

Be prepared to spend some money because filter components and consultants fees are not cheap.

W2XJ
Posts: 89
Joined: Mon Dec 03, 2007 12:15 pm

Re: Combining two AMs at one site

Post by W2XJ » Thu Oct 27, 2016 3:43 pm

What was already said plus there will be enough impact on the DA that it will have to be re-tuned.

User avatar
Deep Thought
Posts: 3208
Joined: Thu Mar 20, 2008 9:23 am
Location: La Grange, IL
Contact:

Re: Combining two AMs at one site

Post by Deep Thought » Thu Oct 27, 2016 5:39 pm

W2XJ wrote:What was already said plus there will be enough impact on the DA that it will have to be re-tuned.
If done properly the impact is minimal. I rarely have to spend more than a few hours getting parameters back to normal even on a four or five tower array. If you see big changes then the pass side of the filters is not designed or tuned properly.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

jammerdave
Posts: 118
Joined: Tue May 31, 2011 9:03 pm
Location: West Sacramento, CA

Re: Combining two AMs at one site

Post by jammerdave » Fri Oct 28, 2016 10:46 am

Talk to Kintronics, IMHO... pretty easily done, as said before. Quite a few around here like that. Probably more as land value goes up.


http://www.kintronic.com/product-catego ... -products/
Deep Thought wrote:
W2XJ wrote:What was already said plus there will be enough impact on the DA that it will have to be re-tuned.
If done properly the impact is minimal. I rarely have to spend more than a few hours getting parameters back to normal even on a four or five tower array. If you see big changes then the pass side of the filters is not designed or tuned properly.

User avatar
Deep Thought
Posts: 3208
Joined: Thu Mar 20, 2008 9:23 am
Location: La Grange, IL
Contact:

Re: Combining two AMs at one site

Post by Deep Thought » Fri Oct 28, 2016 12:47 pm

jammerdave wrote:Quite a few around here like that.
I just came back from working on one of those around you on Weds...1380/890, new nighttime operation for 890 using the day site. :mrgreen:
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

jammerdave
Posts: 118
Joined: Tue May 31, 2011 9:03 pm
Location: West Sacramento, CA

Re: Combining two AMs at one site

Post by jammerdave » Fri Oct 28, 2016 12:57 pm

I know the site, I was chief at salem up to '08. Haven't seen it since.

Deep Thought wrote:
jammerdave wrote:Quite a few around here like that.
I just came back from working on one of those around you on Weds...1380/890, new nighttime operation for 890 using the day site. :mrgreen:

COMMENG
Posts: 95
Joined: Wed Dec 18, 2013 4:30 pm
Location: Midwest

Re: Combining two AMs at one site

Post by COMMENG » Fri Oct 28, 2016 6:10 pm

kkiddkkidd wrote:
COMMENG wrote:
What is your background and experience in BC engineering? Undoubtedly, the 5kW 5 tower site is Directional. If your station is licensed for a 1kW non-D AM, how could you possibly duplex a non-D AM transmitter into a Directional site?

COMMENG
Pray do tell why you can't duplex a ND onto a DA. There are lots of them around.
You're right Kidd, I should have stated that differently.

What I meant to say was: "With all of the complexities involved, why would you want to diplex unless you are losing the land to the original site?"

There is a lot of extra equipment (and maybe housing) to purchase and balancing of the RF system would not be a simple matter.

COMMENG

User avatar
Deep Thought
Posts: 3208
Joined: Thu Mar 20, 2008 9:23 am
Location: La Grange, IL
Contact:

Re: Combining two AMs at one site

Post by Deep Thought » Fri Oct 28, 2016 6:23 pm

It really is not that difficult nor expensive unless the frequency spacing is under 100 KHz. Three additional parts in each ATU output network leg. Sometimes I can use the existing output coil as part of the trap reactance correction and that means only two new parts. If the two stations are close in frequency the filter complexity increases fast but I've successfully done them as close as 60 KHz.

It is cost-effective especially when you consider the continued maintenance costs of a separate site. Combined sites can be good for the host and the added station.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

Tom Osenkowsky (RIP)
Posts: 11
Joined: Wed Mar 16, 2016 4:38 pm

Re: Combining two AMs at one site

Post by Tom Osenkowsky (RIP) » Tue Nov 01, 2016 7:54 pm

You must evaluate the entire project from both a business and technical perspective. There are component costs, labor costs for component installation and adjustment, DA retuning, DA proofing (conventional or MoM, if applicable), lease expenses, STL and miscellaneous costs. After due consideration is this project economically viable in the long term?
There isn't a right or wrong answer. It depends on how much revenue the station is generating, expected to generate and what the payback and term of payback is. Too often only the technical terms of the equation are considered and the business terms are ignored or not fully considered.
What you propose is possible and the services of an experienced consultant will be worth the investment so an informed decision can be made.

Lee_Wheeler
Posts: 82
Joined: Sun Jul 24, 2016 1:53 pm
Location: Kansas City

Re: Combining two AMs at one site

Post by Lee_Wheeler » Tue Nov 01, 2016 8:48 pm

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. It wasn't really diplexed but it might as well have been. We stuck a 4 tower 1550 parallelogram in the 1/2 wave space between the towers on the 680 array.

The MoM proof was what actually made that viable since the proofs would have been insane without it. They had Gary Cavell and Lynn Willoughby do the proof and it was done and the parameters accepted by the Commission for both stations in about a week from the start of network analyzer measurements.

...Lee

Post Reply