1984 called... (EF Johnson)

[tunnelmot]

I actually used both of those EFJ's (T-Band, 800mhz and 900 mhz) in my various careers over the years. ROCK solid rigs, crisp audio. LTR was (is?) a pretty solid trunking protocol. Huge radios, but again the EFJs were extremely reliable units for commercial use.

On a personal note I always liked EFJ's design aesthetic.

 

[KevinC]

One more thing….. a drawback to the 8700 was we had LTR freqs below 856 mHz. Which when the 8700 was designed was not for trunking, so you had to go into the “nibble routine” in the programmer to enter channel numbers below 856. A pain, but a saved PROM as a template saved a lot of time.

 

[KevinC]

Crap, one more thing. It’s been a looong time….didn’t the 8700 use a 123 PROM? Or am I completely wrong on the number?

 

[AM909]

Crap, one more thing. It’s been a looong time….didn’t the 8700 use a 123 PROM? Or am I completely wrong on the number?

82S123, just like the AMPS cell phones of the day. Ah the memories.

 

[FFPM571]

The private Ambulance company I worked for in the mid 80's had the same radio They had it programmed in Semi duplex so you could not hear other rigs. Few select radios that were for managers had it programmed in on a button if you held it in for like 5 seconds it would go in to full

 

[AM909]

The private Ambulance company I worked for in the mid 80's had the same radio They had it programmed in Semi duplex so you could not hear other rigs. Few select radios that were for managers had it programmed in on a button if you held it in for like 5 seconds it would go in to full

I saw one of these the other day. Base transmits on ID 10 and listens on ID 20. Mobiles transmit on ID 20 and listen on ID 10 only. Boss mobiles can switch to a second "channel" that listens to both ID 10 and ID 20 to hear other mobiles.

 

[Echo4Thirty]

The "split" mode of TGs seems to still be unique to LTR. Back in the day in Jacksonville FL we had an 800 MHz LTR system for the school busses that the dispatcher TXd on a different ID than the busses. This was so the busses did not chit chat with each other, similar to how taxi systems are sometimes built. I have never seen a trunked format that would allow you to do that and wondered why.

Oh and they used @KevinC 's favorite radio, the 8700 but the fancy version with the channel knob and display.

Side story, I once was a Flea Market somewhere in Texas and a radio caught my eye. It was an 8700 but it still had the "Property of Duval County School Board" tag on it. Naturally I had to buy it for the shelf. Never could quite figure out how an obsolete Jax FL radio ended up on a flea market table in TX.

 

[KevinC]

The "split" mode of TGs seems to still be unique to LTR. Back in the day in Jacksonville FL we had an 800 MHz LTR system for the school busses that the dispatcher TXd on a different ID than the busses. This was so the busses did not chit chat with each other, similar to how taxi systems are sometimes built. I have never seen a trunked format that would allow you to do that and wondered why.

Oh and they used @KevinC 's favorite radio, the 8700 but the fancy version with the channel knob and display.

Side story, I once was a Flea Market somewhere in Texas and a radio caught my eye. It was an 8700 but it still had the "Property of Duval County School Board" tag on it. Naturally I had to buy it for the shelf. Never could quite figure out how an obsolete Jax FL radio ended up on a flea market table in TX.

8710.

If you were really fancy you gave each bus its own ID and used “block decode” on the base with an external display to show the unit talking. I don’t remember the name of the feature, but in the mobiles you also used a feature like block decode but it kept them from transmitting when any ID in the range was being used. Of course this only worked if everything was on the same home channel.

 

[Echo4Thirty]

We were not that fancy.

 

[KevinC]

We were not that fancy.

And of course the validator didn’t recognize any ID above 250, so hex edit a Standard HX-580 codeplug and use ID 254 and you can bootleg on any LTR system. Hopefully they closed that loophole, but in the 90’s I could use any LTR system I wanted by using that trick. Notice I said I could, not I did.

Actually their were 2 you couldn’t use (don’t remember the ID’s though). One indicated a RIC call and the other was for a BSI call. So that left you 2 ID’s that couldn’t be tracked or turned off.

 

[Mikey69]

There are two versions of the Trident Raider manual on the "Other Manufacturers" page at repeater-builder.

I help maintain 40+ channels of LTR scattered across 8 sites.

If anyone has a Trident Raider Extreme manual - even a PDF - I'd like to have a copy.

I'd also like to find a few more Raiders and a few Extremes (the Extremes just to experiment with).

I like the fact that you can manage the Tridents with nothing more than a Televideo terminal emulator
(ProCommPlus) where the Zetron and CSI equivalents need a management program that runs under MS-DOS.

 

[lenk911]

I worked for EFJ selling these in 1984. It was a great product and LTR was a great trunking concept. One big problem... I understand EFJ forgot to patent it or not in time. Offshore manufacturers (Uniden) adopted the LTR format and the dealers found it more profitable to sell those than EFJ. They'd buy LTR repeaters and offshore mobiles.

Multinet was an enhancement to LTR to meet APCO Project 16 trunking and compete with Smartnet and Edacs. All they did is add a control channel to the LTR signalling. The beauty of the system if the control channel failed the system would revert to LTR.

In advanced MotoTRBO systems, Motorola uses LTR's concept of a home channel so it lives on. You almost get the benefits of a 100% (FB8) control channel without needing the keyed down transmitter. No licensing hurdles as required with a FB8 control channel.

 

[16b]

This was a fun thread to read through. My dad and I had a few 8655s many years ago with what I'm guessing was N2MCI's mod to work on 900 ham. They were great radios even though they were already pretty geriatric by the time we got ahold of them.

There are a few LTR systems still running in my area, too. One of the local school districts has a four channel VHF system for buses, and it's set up with the split dispatcher/mobile groups like others have mentioned. I programmed the system in my Kenwood NX210 to monitor the other day and the audio frankly sounds fantastic. I love digital systems--they have lots of great features and the audio quality has come a long way--but there's something I enjoy about a good sounding analog system.

 

[bill4long]

A mighty fine set of door stops ya got there.

 

[mikegilbert]

Speaking of vintage EF Johnson gear. I've got this minty specimen:

 

[Project25_MASTR]

The "split" mode of TGs seems to still be unique to LTR. Back in the day in Jacksonville FL we had an 800 MHz LTR system for the school busses that the dispatcher TXd on a different ID than the busses. This was so the busses did not chit chat with each other, similar to how taxi systems are sometimes built. I have never seen a trunked format that would allow you to do that and wondered why.

Oh and they used @KevinC 's favorite radio, the 8700 but the fancy version with the channel knob and display.

Side story, I once was a Flea Market somewhere in Texas and a radio caught my eye. It was an 8700 but it still had the "Property of Duval County School Board" tag on it. Naturally I had to buy it for the shelf. Never could quite figure out how an obsolete Jax FL radio ended up on a flea market table in TX.

It used to be pretty common for taxi dispatchers to use what was known as a split base setup. The dispatcher's base station was configured just like a normal repeater would be but would be a half duplex radio (well, it could be full duplex and just programmed not to repeat but I never actually ran into that situation). This would allow the dispatcher to hear the taxis and the taxis to hear the dispatch operator but keep the taxis from talking to one another.

I've actually set this up for DMR Tier 2, Motorola's Capacity Plus and Motorola's...I mean Trident's...Connect Plus. What you do is configure the RX group to the normal group ID but configure the TX target to the dispatcher's radio ID. This also allows the dispatcher to initiate private calls as well. I would imagine that just about any signalling method that would let you input a SUID as the TX target and a TGID for the RX group would allow for this as well.

However, since we are talking about some legacy Johnson stuff. This is all on display in Irving.

And yes...we have several displays around with our parent company's historical stuff as well (but I don't go to that side of the building often so I don't take pictures of it).

 

[westcoaster]

Hey!
I see the desk microphone in the second to last picture!

The box and contents were dropped off at a recycling centre several weeks ago.

As a side note.....

I also got several Motorola Radius GM300 radios in the same pile with the Scholer-Johnson LTR trunking firmware ROM.... Apparently that is a bit of a unicorn.....

Was Scholer-Johnson in any way connected to EF Johnson?

GM300 programming help?

I have a bunch of GM300 UHF radios I believe that are set up as trunking radios. I'm attempting to program them using a cheap ebay cable, a windows98 laptop (Acer Extensa 501DX booted into DOS using a floppy disk) and GM300 Americas Radius version R050.00.00 Of course this setup doesn't...

forums.radioreference.com

 

[03msc]

I also got several Motorola Radius GM300 radios in the same pile

Those are somewhat sought after in certain circles, mostly for ham and sometimes GMRS. I've seen them bring $50-100 each if in good condition. I may or may not have two or three myself... use DOS Box to program.

 

[Project25_MASTR]

Those are somewhat sought after in certain circles, mostly for ham and sometimes GMRS. I've seen them bring $50-100 each if in good condition. I may or may not have two or three myself... use DOS Box to program.

Those of us who worked on them remember when you could get them all day long for free. Today, $20 is honestly about as much as I will pay for one...

 

[mancow]

It used to be pretty common for taxi dispatchers to use what was known as a split base setup. The dispatcher's base station was configured just like a normal repeater would be but would be a half duplex radio (well, it could be full duplex and just programmed not to repeat but I never actually ran into that situation). This would allow the dispatcher to hear the taxis and the taxis to hear the dispatch operator but keep the taxis from talking to one another.

I've actually set this up for DMR Tier 2, Motorola's Capacity Plus and Motorola's...I mean Trident's...Connect Plus. What you do is configure the RX group to the normal group ID but configure the TX target to the dispatcher's radio ID. This also allows the dispatcher to initiate private calls as well. I would imagine that just about any signalling method that would let you input a SUID as the TX target and a TGID for the RX group would allow for this as well.

However, since we are talking about some legacy Johnson stuff. This is all on display in Irving.


And yes...we have several displays around with our parent company's historical stuff as well (but I don't go to that side of the building often so I don't take pictures of it).

I see a Stealth25 there. I used to have one of those. They are huge and buggy. I recall the initial advertisements touted frequency hopping but maybe they were referring to the SC-460 built in scrambler not RF hopping.