Federal VHF Mystery Transmitters

ChrisP

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Looking for some help from the Portland area scanner listeners...

Over the past month I have begun hearing some odd radio traffic on an analog repeater on 173.1375 MHz. Sometimes the signal was weak but readable, and others it was very strong. The signal was always analog, with a CTCSS tone of 77.0 Hz. The audio was often an automated voice announcing warnings about voltage being low or being zero.

At first I thought it might be something from the Bonneville Power Administration (BPA) as their radio system is still analog. But then the voice traffic seemed to be talking about the power system serving the repeater site, indicating there was a problem with the UPS power.

I then begin to wonder if it was an image from a nearby amateur repeater site. I have a couple of ham repeater sites near me that sometimes cause images, but when I heard the traffic on 173.1375, I found nothing related on the VHF or UHF amateur bands.

About two weeks ago, I manged to record a lot of voice traffic on this frequency. It was clearly a repeater and had beeps and boops when the users keyed up and finished talking. But there were no call signs or names mentioned while I was listening. The two users certainly sounded like Canadian truck drivers passing through the Portland area. There was discussions of traffic on I-5, various cars or drivers that were catching their attention, and eating plans, but nothing to identify the users.

The truck drivers seemed to disappear, but the mystery deepened this last week when multiple VHF frequencies in the federal band were now all keyed up continuously with no voice and a 77.0 PL tone. The frequencies that are broadcasting full time are:

171.2750

173.1125

173.1375

173.6500


Can anyone plug these in and see if you are hearing a constant carrier with a PL tone?

Thanks!
 

icom1020

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Jul 19, 2004
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From a friend who lives in the area. He thinks the S9 reading might be from Bald Peak

On a mobile UHF 5dB ground plane antenna on the roof in Hillsboro...

171.2750 - S1 with PL
173.1125 - S1 with PL
173.1375 - S9 with PL
173.6500 - S1 with PL
 

Airboss

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Brasstown, NC
171.2750
173.1125
173.1375
173.6500


Can anyone plug these in and see if you are hearing a constant carrier with a PL tone?
Chris, the first two are DoE assignments nationwide and the last two are DH CBP assignments nationwide. If that helps.
 

ChrisP

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Portland, OR
Thanks Chief.

I have logged some activities on these frequencies over the years in various cities, but not sure if the previous users fit in to what I'm hearing here.

- Chris

Chris, the first two are DoE assignments nationwide and the last two are DH CBP assignments nationwide. If that helps.
 

KE7JFF

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I tried replying to you on Twitter, but I left the scanner on the work truck as I drove from North Portland to Clackamas; it was full blast at Rivergate, went away completely as I went past the Moda Center.
 

ChrisP

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Just FYI, I am confident that I located the 173.1375 MHz transmitter at the Willalatin Tanks radio site along Skyline Drive. I was able to pick it up with no antenna on the radio as I drove nearby.

There is currently a Bonneville Power Administration radio site there, but also IWN site 1-020 is there as well.

And I have noticed that the BPA is doing radio site upgrades at various locations on Oregon;

No jumping to conclusions just yet...
 

ecps92

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Taxachusetts
Those list will never be complete as there are many undiscovered or reported and the fact that altho they might be a freq assignment in one part of the country, it is not always used in another part of the country.
I noticed that these frequencies aren't listed in this database...is there a different CPB database somewhere on radioreference, or is this one simply incomplete? Customs and Border Protection (CBP) Scanner Frequencies and Radio Frequency Reference
 

ChrisP

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Portland, OR
Also of note - Listening to the 173.1375 MHz signal, I am randomly hearing some tones. It sounds like a repeater post transmission bee-boop, a pause, then four rapid tones, like a patch disconnect. I’m hearing them maybe a couple of hours apart. It might be random noise or something on the input or remote control circuit causing it. I have not heard any definitive voice transmissions.

Others are reporting the same type of thing on the other frequencies I listed above.

The mystery continues!

- Chris
 
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