[FedCom] Re: 138.925

[Larry Van Horn]

> Anyone have any ideas?
> (Not guesses. Any AF vets in the group?)

As documented in MT's Fed Files column several years ago and also in my 
eBook - The Federal Freq Directory, 138.925 is a nationwide assignment and 
it is a DoD Fire/LE Alarm System data frequency. There are a few oddball 
voice assignments on this one including some renegade AF A-A intercepts, but 
this should for the most part hold up natwionwide.

The allocation in Portland is a hard and confirmed "Fire Alarm: assignment 
and this is based on a more current look at the notes field from a GMF that 
is more current than the last one that was available in the public domain 
(1984).

Under the new DoD VHF LMR bandplan this assignment will not change from its 
present status. To much money invested in the infrastructure at this point 
to change freqs.

As for 139.875, while I have nothing for Portland specific, I have seen 
several assignments on this frequency for Crash Barrier Control-Data Systems 
(aka runway arresting cable system) at various AF installations across the 
country. While I would not consider that a nationwide assignment, there are 
enought on this freq to suggest this as a possible source of your signal.

If I remember correctly Portland Intl uses an arresting gear system on 
runway 10R/28L that is operated from the control tower (remotely). I believe 
it is either the BAK-12 or BAK-14 system that we had at several of the bases 
I was assigned to. Those systems are remotely controlled via a VHF LMR 
frequency (at least that was what the maintenance manual that I looked at 
briefly back in the early 90s at NAS New Orleans indicated).

Larry Van Horn, N5FPW
Brasstown, NC USA
MT Assistant/Review Editor
Milcom/What's New Columnist

----- Original Message ----- 
From: <gfdubois at juno.com>
To: <fedcom at mailman.qth.net>
Sent: Tuesday, October 07, 2008 5:42 PM
Subject: [FedCom] Re: 138.925


> Speaking of weird signals, I could use some help with one.
>
> There has been a digital signal on 138.925 coming from the ANG base at
> Portland International for decades now.
> According to the IRAC database, it is a fixed station transmitting with
> ten watts. I always assumed it had
> something to do with a/c navigation, but I don't think so. For one, we
> have gone through three different aircraft in the
> last 30 years, and it's still there. And we have a TOD generator, on
> 397.0.
> The "Special Notes" code is S361, which means "multiple transmitting
> and/or receiving stations operating at fixed locations..."  But
> everything the ANG owns is at Portland Arpt. (Or Klamath Falls, in
> southern Oregon.) And the signal is always the same strength.
>
> If you listen to it, it transmits at irregular intervals.
>  http://mywebsite.mysite.com/files.html
> (There's another one on 139.875 that's been there for the last ten years
> or so. I have no idea what that one is either.)
>
> Anyone have any ideas?
> (Not guesses. Any AF vets in the group?)
>
> Thanks.
>
> George DuBois
>
>
>
>
>
>
>
>
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