TENNELEC MCP-1 MemoryScan

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mfn002

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I just picked up one of these for $25 on eBay. Upon powering it on, I noticed two (major) issues: 1) The LED display flickers and some parts are dim, and 2) It doesn't receive anything (even the local SO VHF repeater, which is only a mile or so from my house). What it does receive sounds like bleedover and doesn't break squelch. What I would like to know is whether this is repairable or not.
 

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twobytwo

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Neat looking radio. Ive never seen it before. What is the manufactured date on it?
 

ChrisP

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I had one of those in 1975 or 76. It was very cool for the day, but only 16 channels. It wasn't a good scanner even then - it weighed a ton, generated a lot of heat and the CPU was so noisy it splattered noise all over the VHF and UHF bands. I recall it had real selectivity problems too. I had to limit it to strong, local repeaters to get much use from it. I think I sold it after only a year or so.

- Chris
 

mfn002

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I had one of those in 1975 or 76. It was very cool for the day, but only 16 channels. It wasn't a good scanner even then - it weighed a ton, generated a lot of heat and the CPU was so noisy it splattered noise all over the VHF and UHF bands. I recall it had real selectivity problems too. I had to limit it to strong, local repeaters to get much use from it. I think I sold it after only a year or so.

- Chris
That might explain the RX problems I've been having with it. It's so bad, that I'm getting our local Weather Radio station on 162.550 all the way down on the local Sheriff's Office Primary channel (155.415). I suspect the display problem has to do with a capacitor because I noticed that some of the LED display segments started out faint before coming to (relatively) full brightness when I first plugged it in.
 

MarkPalmer

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A bit old a thread but....
You have to keep an open mind when looking back on the Tennelec MCP-1 today. Yes, it was a horrible performing radio, but technology wise it laid one heck of a foundation. This was the first keyboard programmable, digital display, PLL scanning radio on the market. People were floored setting their eyes on this scanner in 1976 at the Chicago Consumer Electronics Show. A couple years before it in 1974, Tennelec came out with the first pushbutton programmable scanner with the MS-1 that eliminated the need for scanner owners to purchase crystals. Tennelec’s digital scanner circuit designs from Peter Pflasterer were excellent and innovative for utilizing digital integrated circuit designs that were new to the market at the time.

The trouble for Tennelec came in getting the product from schematics to something that was good enough to put in a box and market to the public. Poor physical product design, lack of acceptable reliability testing, poor manufacturing techniques, and lack of manufacturing quality control came in to play together for Tennelec with the MCP-1. A quick peek inside of an MCP-1 is all that is needed to see how truly awful the end design was. I can’t quite figure this out, because Tennelec was known for making world class high end radiation measurement instrumentation prior to getting in the consumer scanner radio market. I believe they fell on their faces with budgets, knowing they had to develop consumer electronics to a low price point, something they were not used to with radiation equipment. The end result of unacceptable product quality for the consumer products division helped to drive Tennelec to bankruptcy. But from punishment came eventual reward. Both Peter Pflasterer and Tennelec vice president William Baker would move on to Electra/Bearcat outside of Indianapolis. Here, these two men along with a few other Electra developers were able to advance the synthesized scanning radio in to a world class performer with such products as the Bearcat BC300. After Electra was absorbed from Masco of Indiana in to Uniden, Baker would go on to become Uniden North America’s vice president.

With what we have today for scanner radios repairing a vintage non-working (virtually every one left out there) Tennelec MCP-1 is more of an exercise for challenge and enjoyment rather than ending up with a scanner one would actually want to use today.

-Mark-
 

harryshute

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Thanks for the background on the unit and the developers. I too had one of these and can agree with the performance issues but all I had at the time was a Radio Shack 16 channel crystal scanner. I bought the unit for cash from a fellow in a Lincoln in front of the United Nations building in NYC. All this was set up while I was back home in Canada looking at an ad in a magazine.

I soon sold the Tennelec and moved onto the SBE which had a card you pulled numbers off of to get the correct frequency and the reception on it was crisp. It had only eight channels but all you had to do was change the card and you had another eight totally different channels.

It was an exciting time in scanner development.
 

garys

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outside of Indianapolis. Here, these two men along with a few other Electra developers were able to advance the synthesized scanning radio in to a world class performer with such products as the Bearcat BC300. After Electra was absorbed from Masco of Indiana in to Uniden, Baker would go on to become Uniden North America’s vice president.
-Mark-
The store I worked in back then sold the earlier Tennelec scanners, but not this one. It's been a lot of years, but I recall that just about every one we sold came back. Total junk from a production aspect.

As you note, they did drive both Electra and Regency into the programmable era. Electra with the Bearcat 101, which had it's own teething problems, and Regency with the "Touch" series of scanners.

BTW, I had a Bearcat 300 and the involvement of former Tennelec employees would explain why it was the POS it was. It was both deaf and non selective at the same time. Far worse than the Bearcat 250 it replaced.
 

garys

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The SBE scanners were solid performers. Even after the left the scanner market, people still liked them. I remember that one enterprising young guy actually started making the cards when they weren't available from SBE. I think Sears sold the same scanner under it's brand as well.

Thanks for the background on the unit and the developers. I too had one of these and can agree with the performance issues but all I had at the time was a Radio Shack 16 channel crystal scanner. I bought the unit for cash from a fellow in a Lincoln in front of the United Nations building in NYC. All this was set up while I was back home in Canada looking at an ad in a magazine.

I soon sold the Tennelec and moved onto the SBE which had a card you pulled numbers off of to get the correct frequency and the reception on it was crisp. It had only eight channels but all you had to do was change the card and you had another eight totally different channels.

It was an exciting time in scanner development.
 

MarkPalmer

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As much as the guys from Tennelec helped out Electra, Uniden was 100% the life-saver of the Bearcat scanner name. Thankfully they came along when they did and had enough interest in Electra's developments because Masco had enough of Electra at that time. After Electra was starting to get it together with the BC300, they came out with the BC350 alpha-numeric which was a total Mickey-Mouse pile of garbage- many of them didn't work right brand new out of the box. Electra was big on using those QIP package microprocessors from Rockwell International that had an alarmingly high failure rate. That nonsense was gone when Uniden produced the BC800XLT, a scanner that would actually last a very long time without needing repairs, something people weren't used to with the Electra/Bearcat name.

-Mark-
 

garys

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I loved that 350 when it came out, but only saw one in a store and never got a chance to buy one. The alphanumeric display was incredible for the time!. Too bad it was such a POS.

Then again, the early RELM scanners also had a great feature set, but were essentially useless because of the craptastic front end.

As much as the guys from Tennelec helped out Electra, Uniden was 100% the life-saver of the Bearcat scanner name. Thankfully they came along when they did and had enough interest in Electra's developments because Masco had enough of Electra at that time. After Electra was starting to get it together with the BC300, they came out with the BC350 alpha-numeric which was a total Mickey-Mouse pile of garbage- many of them didn't work right brand new out of the box. Electra was big on using those QIP package microprocessors from Rockwell International that had an alarmingly high failure rate. That nonsense was gone when Uniden produced the BC800XLT, a scanner that would actually last a very long time without needing repairs, something people weren't used to with the Electra/Bearcat name.

-Mark-
 

dwelty

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My Bearcat 300 is still cranking right along, some almost 34 years after purchase at the Dayton Hamvention in April 1981. With the Avanti AV801 antenna at 25 feet, I could pickup more then our firehouse radio right down the street, with an antenna at 65 feet! Mine has always been very sensitive and selective as well, so much a bought another one at Dayton 3 years ago and had to replace some capacitors, but it's humming along too. I too had experience with Tennelec scanners, not the TCP1 but the model that used a binary code to input frequencies. 16 channels, it was deaf and you could only put in frequencies on the chart.
 

MarkPalmer

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The Electra BC350 was a beautiful looking radio, and a great concept at the time. My BC350 developed the processor problems that would eventually plague every single one of this model. Some days it would run all day with no problems. Other days it would continuously lock up on a channel, or randomly both displays would just go blank as if it were turned off. Sometimes the displays would start flashing funny things like E.T. was trying to communicate through the stupid thing. I don’t know if the problem was with the microprocessor itself or the ROM memory, but neither Electra nor Uniden found a solution to this problem for the slew of BC350 owners who experienced it. Electra was being bought out by Uniden at the time the problems became intense. Electra’s answer was to discontinue the model, and wash their hands with it. It was BS for those who paid in the neighborhood of $450.00 for the BC350 in the mid 1980’s only to have to send it back to Electra multiple times with no real fix, than finally just chuck it in the trash after a few miserable years of struggling with it.

I have a couple of BC300's that still work fine, I still listen to them regularly.

-Mark-
 

MarkPalmer

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After working on one extensively in my electronics lab, I figured out what made the Electra/Bearcat BC350 alpha-numeric so unreliable. (Something that Electra couldn't figure out.) So if you see one of these very rare birds on E-Bay for a few bucks, you can probably get it going again. You can see some photos of this work on Facebook by typing Mark's Late Night Laboratory in to the search.

1. It uses a 52 pin Rockwell QIP microprocessor similar to (but not identical to) that of the BC300. The uP is mounted in a socket, and mounted upside down on the controller board.

2. The processor has a long aluminum plate heat sink and noise shield glued to the top of it. This shield runs from the controller board out to the back of the radio chassis, where it is attached with a sheet metal screw to a heat sink for the controller power transistors.

3. The processor end of the controller board has a metal noise shield on the component side, and a copper cladded insulated shield on the opposite (top) side. These two shields are heavily soldered together in the corners, making access to the microprocessor impossible without their removal. Hence why no one put any effort in to attempting to fix these as getting in there is a PITA.

4. When the radio is physically moved around, even the tiniest amount of flex of the back chassis will move the heat sink/shield that goes to the microprocessor. This will begin to pull the microprocessor pins loose from its socket, and cause many different types of malfunctions. This explains why some BC350’s didn’t even work when new straight out of the box.

5. The solution: Unsolder the shields from the controller board for access to the microprocessor. They actually unsolder much easier than it looks. Re-seat the uP pins back in to the socket using a small jeweler’s screwdriver. You might find some of the pins are barely in the socket! Cut the end off of the heat sink/shield so it will no longer mount to the back chassis of the radio- I have found it is not necessary for it to do so. The screw however needs to go back in to the heat sink of the power transistors it originally threads in to as they need the rear chassis for cooling. This should bring a dead or malfunctioning BC350 controller back to life and keep the problems from occurring again. If Electra's product designer is still alive.... now you know where you made your critical mistake..... Naaa-naa!

-Mark-
 

lazierfan

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That might explain the RX problems I've been having with it. It's so bad, that I'm getting our local Weather Radio station on 162.550 all the way down on the local Sheriff's Office Primary channel (155.415). I suspect the display problem has to do with a capacitor because I noticed that some of the LED display segments started out faint before coming to (relatively) full brightness when I first plugged it in.
The mainboard and riser sockets were the problem.
Every time the MCP-1 would get to operating temperature, the plastic(Bakelite? putty? haha), would expand and distort. This made connection of the riser boards worse and worse.

The display used a riser board
The keypad used a riser board.
 
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