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Diplexing...how hard is it?

J

JeffDavis98

Does it make it easier if the frequencies are divisible by two, like 700kHz and 1400kHz or 600kHz and 1200kHz?

How expensive and difficult is it to do and are operators open to it?
 
> Does it make it easier if the frequencies are divisible by
> two, like 700kHz and 1400kHz or 600kHz and 1200kHz?
>
> How expensive and difficult is it to do and are operators
> open to it?
>
Jeff,

I was ops manager at a station that built a diplex for a couple
of stations in Tallahassee, Fla.

1330 AM owned the tower and the property, with a 231 foot tower
and 5 kw-day.

1410 AM had just been purchased by Cumulus and the property owner of their
then-tower refused to allow them on the property, in essence meaning
they had a station with no tower site and an approaching FCC deadline.
1410 had 5 kw-day and several step-downs to a low of 18 watts overnight.

At the base of the tower are two ATUs made by Kintronics, one for 1330 and the other for 1410. Engineer Ron Rackley was brought in to make the system work, as no one in this area had ever done it, or for that matter, knew what "diplex"
even meant!

It took several weeks for them to wire and connect up the ATUs and take all
the necessary readings.

1330 did get some bleed-over from 1410 in the audio and fax line until some filters were installed.

However, 1330 did get a new source of revenue from the tower rental. The
diplex system still operates today with very little trouble.

Rackley is very knowlegable about this.

I don't know how expensive it was, as Cumulus paid the bulk of it since
they were the ones pursuing it. The FCC deadline did get met, and passed.

Hope this helps..from someone who kind of went through the process!<P ID="signature">______________
Proudly remembering the days of the hometown "country giant" radio stations now at
http://www.live365.com/stations/alanmccall</P>
 
> At the base of the tower are two ATUs made by Kintronics,
> one for 1330 and the other for 1410. Engineer Ron Rackley
> was brought in to make the system work, as no one in this
> area had ever done it, or for that matter, knew what
> "diplex"
> even meant!

Ron and Jack Sellmeyer are two of the best in the business...
If anyone can do a diplex, they can...if the freqs are harmonically related,
that may prove to be tougher in my opinion than non related freqs...
(2nd harmonic issues, etc)
 
Does the process in any way degrade either signal? Obviously sticking a station onto a stick that's way too short would, but other than that... ?


> > At the base of the tower are two ATUs made by Kintronics,
> > one for 1330 and the other for 1410. Engineer Ron Rackley
> > was brought in to make the system work, as no one in this
> > area had ever done it, or for that matter, knew what
> > "diplex"
> > even meant!
>
> Ron and Jack Sellmeyer are two of the best in the
> business...
> If anyone can do a diplex, they can...if the freqs are
> harmonically related,
> that may prove to be tougher in my opinion than non related
> freqs...
> (2nd harmonic issues, etc)
>
 
> Does the process in any way degrade either signal? Obviously
> sticking a station onto a stick that's way too short would,
> but other than that... ?

No any different than if the station was feeding a similar tower by itself..
The two xmtrs donot 'see' each other due to the filtering at the tower (s)...
 
> Does the process in any way degrade either signal? Obviously
> sticking a station onto a stick that's way too short would,
> but other than that... ?
>
> No, not at the Tallahassee diplex either (see CW's post below.)
The stations are filtered at the tower.


> > > At the base of the tower are two ATUs made by
> Kintronics,
> > > one for 1330 and the other for 1410. Engineer Ron
> Rackley
> > > was brought in to make the system work, as no one in
> this
> > > area had ever done it, or for that matter, knew what
> > > "diplex"
> > > even meant!
> >
> > Ron and Jack Sellmeyer are two of the best in the
> > business...
> > If anyone can do a diplex, they can...if the freqs are
> > harmonically related,
> > that may prove to be tougher in my opinion than non
> related
> > freqs...
> > (2nd harmonic issues, etc)
> >
>
<P ID="signature">______________
Proudly remembering the days of the hometown "country giant" radio stations now at
http://www.live365.com/stations/alanmccall</P>
 
Re: Thanks

We just set up a diplex last year. It is a time consuming project and expensive. As I recall we had about $150 into hardware (Kintronics boxes at the base of each tower, a phaser and misc filters). I don't know what the engineering bill finally came to, but it wasn't cheap! We were also hitting the deadline and I had to bring in everyone I could find to come help out. (we finished with 36 hours to spare!

Since the install, we have had no significant problems to report.

KT
 
> How expensive and difficult is it to do and are operators
> open to it?


With all the answers below the RF side has been pretty well covered.

Now, a couple of things that get overlooked:

1. AC power. Does the building have sufficient capacity for another
transmitter and all the various peripherals? Does the available
powerline have sufficient capacity? Not just the lines themselves,
but any transformers between your site and the closest substation?

2. The "other" RF factors; How close is the transmitter building
or buildings to the tower? What's the projected RF exposure level
inside with both transmitters fired up (probably not from the
indoor equipment itself, but coming off the tower)? How about
the fence around the tower? It may have to be moved further away
from the tower for FCC compliance.

#2 is probably inexpensive but #1 has the potential to cost as much
as, or even more than, the diplexing equipment/engineering services.

But...it's no impossible that everything might be perfectly OK. Best,
though, to find out ahead of time.
<P ID="signature">______________
Be on they guard against the good and the just! They would curcify those who devise their own virtue.
--Friedrich Nietzsche</P>
 
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