NH DRED Tower-to-Tower Conversion to FM from AM & Use

[GraniteScanner]

Hi Everyone,
I have always been interested in the DRED fire tower frequency particularly because of the fact it uses AM (or at least it used too).

Frequency	License	Type	Tone	Alpha Tag	Description	Mode	Tag
31.900	BM	CSQ	DRED Towers	Fire Towers (Tower-to-Tower)	AM	Fire-

I recently dug into the ULS and it turns out after checking the Emission Designator every licensee on this frequency (of which there are still many) have switched to narrow band FM.
Click here for the old license with AM (KCA698 - Terminated)
Click here for the new license with FM (KCA208 - Active)
Hopefully people find this information useful but I have a follow up. Has anyone ever heard this freq. in use? It has not been logged ever on Scan New England as far as I have seen.
This question may not be answered but would anyone happen to know if the equipment to operate on this VHF-Low system is still deployed? What radios where in use when it was running in AM mode?
Lots of questions and lots of info, I know, but this frequency seems to have faded into the background. It wouldn't surprise me if this was a backup system and everyone is using the new P25 system.
Thanks for the read. Sorry for the long post

 

[ecps92]

Wow memories of the old Goonie boxes in the towers using "AM"

I can't remember exactly the last time I heard 31.9000 in AM mode, but it was in the towers for years and my last reception of it would
have been late 90's / early 2k's in the Newfound area.

Even the Maine towers had access to it.

Within the past few years, did a visit to the Lancaster tower and the "AM" radio was still seen, altho the tower was not functionally being staffed at that time.

Hi Everyone,
I have always been interested in the DRED fire tower frequency particularly because of the fact it uses AM (or at least it used too).

Frequency	License	Type	Tone	Alpha Tag	Description	Mode	Tag
31.900	BM	CSQ	DRED Towers	Fire Towers (Tower-to-Tower)	AM	Fire-

I recently dug into the ULS and it turns out after checking the Emission Designator every licensee on this frequency (of which there are still many) have switched to narrow band FM.
Click here for the old license with AM (KCA698 - Terminated)
Click here for the new license with FM (KCA208 - Active)
Hopefully people find this information useful but I have a follow up. Has anyone ever heard this freq. in use? It has not been logged ever on Scan New England as far as I have seen.
This question may not be answered but would anyone happen to know if the equipment to operate on this VHF-Low system is still deployed? What radios where in use when it was running in AM mode?
Lots of questions and lots of info, I know, but this frequency seems to have faded into the background. It wouldn't surprise me if this was a backup system and everyone is using the new P25 system.
Thanks for the read. Sorry for the long post

 

[GraniteScanner]

Wow, interesting. Goonie boxes is a funny nickname lol. Ill have head out to Lancaster sometime and take a look. Thanks for shareing.

Wow memories of the old Goonie boxes in the towers using "AM"

I can't remember exactly the last time I heard 31.9000 in AM mode, but it was in the towers for years and my last reception of it would
have been late 90's / early 2k's in the Newfound area.

Even the Maine towers had access to it.

Within the past few years, did a visit to the Lancaster tower and the "AM" radio was still seen, altho the tower was not functionally being staffed at that time.

 

[ecps92]

all were Tubes

Redirect Notice

Wow, interesting. Goonie boxes is a funny nickname lol. Ill have head out to Lancaster sometime and take a look. Thanks for shareing.

 

[GraniteScanner]

Tube radios even that far into the 90s? That's an impressive service life.

all were Tubes

Redirect Notice

 

[jmarcel66]

Widespread usage of 31.90, especially in AM ended several years ago. I don't know, but don't think its used anymore. It may have been the original fire service two-way radio frequency used in NH. There was reference to it on Lakes Region's old list of signals, with a signal advising to "Switch to 31.90". That segment of Low-Band was eventually re-allocated to Military Use, with the State of NH being grandfathered.

If I remember, they used General Electric tube radios, very carefully cared for. They may have looked like this.

 

[a417]

Tube radios even that far into the 90s? That's an impressive service life.

Look into broadcast radio, tubes still going as we speak.

 

[GraniteScanner]

Interesting. I bet they updated the licensee to hold onto that grandfathered frequency. Thanks for the info on the radios, I'm going to look into that.

Widespread usage of 31.90, especially in AM ended several years ago. I don't know, but don't think its used anymore. It may have been the original fire service two-way radio frequency used in NH. There was reference to it on Lakes Region's old list of signals, with a signal advising to "Switch to 31.90". That segment of Low-Band was eventually re-allocated to Military Use, with the State of NH being grandfathered.

If I remember, they used General Electric tube radios, very carefully cared for. They may have looked like this.

 

[GraniteScanner]

Yeah I have heard of AM and even shortwave stations using tubes, that just blows my mind. How do they find the tubes for that stuff.

Look into broadcast radio, tubes still going as we speak.

 

[W1KNE]

Yeah I have heard of AM and even shortwave stations using tubes, that just blows my mind. How do they find the tubes for that stuff.

There are a few tube manufacturers who make RF tubes for transmitters. There are other companies that also rebuild tubes. Mostly in radio used in high powered FM transmitters, but those are getting fewer and fewer. In the TV world, we still had very large tubes known as "IOT"s (Inductive Output Tubes). Up until the 2019 repack, just about every UHF station had one. But they've been replaced (thankfully) by much more reliable solid state rigs. Shortwave Stations still almost exclusively use tubes, do the very high power transmission they use.

 

[GraniteScanner]

That's interesting, where those tubes part of the signal chain to the antenna?

There are a few tube manufacturers who make RF tubes for transmitters. There are other companies that also rebuild tubes. Mostly in radio used in high powered FM transmitters, but those are getting fewer and fewer. In the TV world, we still had very large tubes known as "IOT"s (Inductive Output Tubes). Up until the 2019 repack, just about every UHF station had one. But they've been replaced (thankfully) by much more reliable solid state rigs. Shortwave Stations still almost exclusively use tubes, do the very high power transmission they use.

 

[a417]

That's interesting, where those tubes part of the signal chain to the antenna?

Yep. they amplify the signal to the flame-throwin' levels that go to the antenna. Older radios did use the tubes for other reasons, but the monster tubes that @W1KNE was mentioning were primarily left in the final amplification stages.

 

[skip0157]

All of DNCR is now VHF P25. The towers are on 151.3775. As a side note the north and south repeater systems were upgraded this year and have better coverage now. The towers, Rangers and Patrolmen also use the repeaters.

 

[n5ims]

Our 20KW FM broadcast transmitter was being moved from the transmitter room at the base of a tower where they upgraded the transmitter to a shiny new one and gave us the old one, it wasn't the tubes on the final that were impressive, it was the power transformer on the final power amplifier. That sucker was huge and very heavy. I'd say it was about 3 1/2 feet tall and 18" wide and 6"+ thick. It weighed over 200 lbs just for the transformer. Getting the transmitter cabinets (2 for the transmitter and 2 more for the accessories) up the first 16 stories was easy since we could use the elevator. The top floor to the roof was the hard part since it was 3 flights of stairs.

The first cabinet was pretty light since it held the exciter (10-watt RF output) that was removed for transit and the intermediary power amp (250-watt RF output). It was about 7 feet tall, 4 feet wide, and 20" thick. Probably weighed a bit over 150 pounds. The PA cabinet was about the same physical size but had some pretty hefty components. With the transformer mentioned above and the final tubes removed, it was still heavy enough that we had to use a come-along and lots of manpower to get it up the stairs.

The first attempt (unsure if it still had the transformer installed at the time) the handles on the hand truck broke off near the top of the stairs, causing it to slide down the stairs and into the wall, crashing through enough that the VP that had that particular office was staring at us through the holes in the wall made by the flying transmitter. He was cool about it when we showed him what we were doing and got building maintenance there quickly to verify that nothing was seriously damaged and repair the damaged wall. He was so cool about it that he said that he'd been trying to get maintenance to repaint that wall for a couple of years and now they'll have to. Maintenance refused to help move the transmitter and only suggested that the next time we get a crane. We checked everything out visually and it all looked good so we remounted the transformer and tubes and everything tested good so we were very lucky with that episode.

 

[12dbsinad]

They should just convert it to 31.90 FM. Plethora of equipment that could be used then and will bring it into solid state era. It's perfect for tower-tower comms

 

[GraniteScanner]

They did convert their license to FM, however everything on on the VHF High p25 system now. But VHF low would still be perfect for tower to tower.

They should just convert it to 31.90 FM. Plethora or equipment that could be used then and will bring it into solid state era. It's perfect for tower-tower comms

 

[12dbsinad]

They did convert their license to FM, however everything on on the VHF High p25 system now. But VHF low would still be perfect for tower to tower.

Ageed, but probably not worth the effort for as little as the towers are staffed. They're are enough modern ways to communicate nowadays I'm sure maintaining lowband on the towers isn't top priority, and they need VHF in the towers anyways

 

[GraniteScanner]

Yeah true, still surprised that many agencies not even just DRED are still re-licensing for VHF Low

Ageed, but probably not worth the effort for as little as the towers are staffed. They're are enough modern ways to communicate nowadays I'm sure maintaining lowband on the towers isn't top priority, and they need VHF in the towers anyways

 

[creeperjeep]

Unfortunately new low split lowband equipment is rare as hens teeth

 

[GraniteScanner]

I saw Woxun made some, but who is going to buy from them for a fire radio system.

Unfortunately new low split lowband equipment is rare as hens teeth