• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Why do I go to hamfests?

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Did you design this guy? I bought it new in 1997, along with a bunch of P1225 (?) HT's.

Win W5JAG
 

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US hams were not required to support govt radio services, but they (through MARS) were enticed to do so. Free or cheap military surplus, and at least in the 1960's, a few extra radio frequencies were available to those who signed up. There were military traffic nets that required periodic check ins usually to relay messages from overseas military personnel to their relatives back home. Remember the cell phone, the PC and the internet didn't get invented until the 80's.
That's cool stuff, never heard much about MARS until this thread. Have read about GWEN though. I have an old BC348 on the bench from 1945 that works great, still in its conformal coating for Far East use (maybe to be used in Operation Downfall?). Wonder if that is from a MARS offering.
 
Did you design this guy?

No. The Motorola plant in Plantation Florida where I worked did only high tier radios for public safety (police, fire, military.....). That doesn't mean that well heeled hams, businesses and the like can't buy them, they were just priced to be paid for with tax payer's dollars. The top of the line encrypted police walkie talkie now sells for over $6,000 EACH in quantity (100 or so).

I started there in 1973 hand tuning and assembling HT220's. Each radio was built by one of about 100 technicians. The customer paperwork was in the box as it made its way through the factory. I remember seeing a radio or two with ham call signs, but it was rare.

I then spent 10 years in the calibration lab specializing in factory floor support. If it was in the factory and it broke, I fixed it or got a replacement.

I then did 12 years in one product development group or another designing subsystems that went into hand held radios, starting with the STX and ending with the Jedi line (about a dozen different model numbers).

Then it was about 3 years in an off campus think tank associated with the paging division. I saw the collapse coming there, and jumped to another off campus brain trust which came up with iDEN (Nextel phones). When Sprint bought Nextel, I joined the advanced research group where I stayed until I took the buyout (the get the old timers out plan).

The industrial, and SMR (taxi, construction crew, package delivery trucks) radios were originally designed out of Mount Pleasant Iowa. That plant was sold in 2000 and all design and manufacturing went to Malaysia. I am not familiar with that particular radio, but it was probably designed at one of those two facilities. There should be a label showing where it was made. There was also a manufacturing plant in Reynosa Mexico with design in Mt. Pleasant and Penang Malaysia, but it was shut down about 5 years ago.

The last radio designed in Plantation Florida has just shipped, the facility has been sold, and most of the design engineers are gone. The advanced research group, some marketing and support people are still there in a rented corner of one of the 5 buildings. The other buildings are being refitted as a medical park. Motorola will probably be gone completely in a year or two.
 
Speaking of Motorola, many years ago I got lucky (no, not that kind of lucky :D) and got access to an 800 number that was somewhere in Phoenix AZ (I think) for their semiconductor operation. This nice girl "Pat" would be happy to send you free transistor samples for the asking. I needed about twenty high voltage TO3 transistors for an ENI amplifier I was repairing. She didn't have the exact part number I needed, so she sent me the next closest thing. They worked fine. Then perhaps two weeks later I get a surprise red label package delivered by "Big Brown" with twenty of the original type I requested from her. Another time came some 800 volt TO3 mosfets as well as a few expensive "helicopter style" RF transistors. That was the good old days!
 
...glorious story... at that time I was on the other side of the Iron Curtain )) Our designs were totally switching stuff on semiconductors, quite powerful with none of tubes, but I realized soon enough where it all goes to safe-settle myself with the computers... as I can judge from their production line they are still producing it based on some of my ideas, as those are difficult to overcome due to physics laws ))
 
SPS (the Semiconductor Products Sector) was a different division of Motorola. It operated as a separate company, which it became, twice (On Semi, and Freescale). They had a sales office in our plant behind the cafeteria. I got to know the sales engineers. They got my friends and I dozens of transistors for our solid state audio amps. I think I built about 100 or so total, of the different "Tiger" series amps with free silicon. The only one we didn't build was the Tigersaurus because we couldn't get the power transformer for cheap. I used those things for home HiFi, car audio and guitar amps.

In the mid 70's I was a "Mr. Fixit" for the night shift factory (4 PM to midnight). My responsibilities were primarily test equipment and fixturing for two way radio production. There were other Mr. Fixits for the other production operations, microelectronics (ceramic hybrid modules), RF crystals, pagers, and facility maintenance. We were all friends and helped each other.

I came in to work one afternoon after spending the morning sailing up and down Ft. Lauderdale beach on my small sailboat, dressed in my usual shorts, tank top and flip flops, to be greeted by several "suits." It turns out that several process engineers had travelled from the SPS plant in Arizona with some defective silicon to use our shiny new scanning electron microscope, only to find it broken. A call had been placed to the manufacturer, but their repair guy was several days out, and they wanted it NOW, so they came in to the cal lab.

The boss refused to even look at it but told them that there was a guy on the night shift that could fix "anything." They looked at me, and really were unsure, but handed me the keys to the room with the half million dollar machine, their pager number (no cell phones in the 70's) and left. After my usual rounds of the factory floor, I gathered my buddies and proceeded to rip into the big grey machine.......

About ten minutes in I spotted a big electrolytic cap that had vented its goo all over the place, so we shoplifted a suitable replacement off of one of the assembly lines, replaced a blown fuse, paged the suits, then sat back and stared.

They had told us not to try to start up the system, but they didn't respond to our page, and we had a new toy in front of us, so......We found the operators manual which was about as thick as a small phone book. You must load your sample then pump the system down to some absurd vacuum level. Their sample was already present, and fortunately there were two HiVac experts among my friends. Crystals and thin film microelectronics both use such systems.

Within about an hour of knob twiddling and reading the manual, we had a picture on the screen. By this time a couple of the SPS guys (without the suits) just showed up. Before they could rip into us for firing up the machine, they saw the display and started twisting knobs......We had to get back to our regular jobs, so we left.

I walked by the room before I left work sometime after midnight, and there were several people who wanted a phone that could call Arizona. There was one in our lab, so I let them in and while one waited for somebody in AZ to be located and call us back, I talked to the other guys.

They were working on the recently announced Motorola MC6800microprocessor, its support chips, and it's successor, the MC6809. Needless to say I had a lifetime of free silicon for my SWTPC 6800 computer system. Even new parts that weren't released, with data sheets, showed up in interplant mail. Sometimes one of the guys would call to ask if we had made them work yet. Usually, we had......If nothing breaks in the factory, we were on our own with all kinds of expensive toys to play with.

Within a couple of years my system had grown to fill half of my workbench, and dim the lights when I turned it on. It eventually got replaced by a TRS80, then an Apple II clone, then a PC clone....The last time I saw my system it was headed for a computer museum at Virginia Tech. That was maybe 1990. It's probably been melted down for its gold content by now.
 
My HT1250 was built in Malaysia. I was pretty disappointed in that. I paid a lot of money for it, and I expected it to be U.S. made like the considerably less expensive radius radios. It's been a good radio, though. Best I recall, it was the only radio in the kilobuckish range that would cover two meters.

Sad to see what has become of Motorola.

Win W5JAG
 
Speaking of Motorola, many years ago I got lucky (no, not that kind of lucky :D) and got access to an 800 number that was somewhere in Phoenix AZ (I think) for their semiconductor operation. This nice girl "Pat" would be happy to send you free transistor samples for the asking. I needed about twenty high voltage TO3 transistors for an ENI amplifier I was repairing. She didn't have the exact part number I needed, so she sent me the next closest thing. They worked fine. Then perhaps two weeks later I get a surprise red label package delivered by "Big Brown" with twenty of the original type I requested from her. Another time came some 800 volt TO3 mosfets as well as a few expensive "helicopter style" RF transistors. That was the good old days!

Part number ENI-409C, perhaps? Originally a Delco part, later Motorola. I used some as replacement horizontal output transistors in a couple of TVs - that's what the base part was designed for. Motorola also made the only TO-3 transistors (2N5038) that would work in the broadband 240L amplifier (10 KHz - 12 MHz). Other brands with the same JEDEC number rolled off at 2-4 MHz. When Moto/ONSemi discontinued that part, ENI had to obsolete that model...

All ancient history here... I'll retire next year after 27 years here.
 
Part number ENI-409C, perhaps?
Nope, it was a MJ16010 for the 1140L amp. (Or was it the 1040L) Anyway I used the MJ16012 which was a little higher gain and they worked well.

I'm familiar with the 240L and have had a few over the years. Lots of fun replacing all those 20 ohm 2W emitter resistors that burned up with the bad 2N5038's. I still have a box of those around somewhere. But it was that first little stud mounted transistor that was the hard one to find. I also have a list somewhere of ENI transistor numbers and equivalents, if there was one. I quit doing these amps a long time age. I have a friend in NY state that used to rebuild them. He had an in with ENI through a friend (John) that worked there. And yes, when Motorola stopped selling TO3 power transistors they screwed a lot of manufactures.
 
I also have a list somewhere of ENI transistor numbers and equivalents, if there was one. I quit doing these amps a long time ago. I have a friend in NY state that used to rebuild them. He had an in with ENI through a friend (John) that worked there. And yes, when Motorola stopped selling TO3 power transistors they screwed a lot of manufactures.

Any chance of getting a hold of that replacement list for ENI transistors?
 
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