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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Tue 19, 2017 12:48 am 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1050
Location: Palos Verdes, CA
John,
The converter transistor in the Motorola 66T1 is a 2N172 and a substitute would be a NTE101. The 2N172 transistor is also used in the Motorola 56T1, Magnavox AM-2, and the Emerson 849. - Mark


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Tue 19, 2017 3:46 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5274
Location: Indianapolis, IN
Thanks Mark---I have the original and the service literature and try to stay away from the "generic" replacements if possible. Since the 2N172 failed, wanted to replace it with another, possibly more reliable part...

And tonight I found one in transistor parts drawer ! Decided to look once again and found two old black GE oval top-hat transistors with no numbers---one was never used. Tested and found that they were NPN's, so tried both in socket which I'd temporarily wired to PCB---both worked well and had the same level of performance, so permanently installed the unused one which had long leads. Had to remove a resistor and ceramic cap to the left and reorient them slightly to make room for the much larger transistor. It barely fit physically with very little clearance on sides. Radio seems to work well now, but need to realign when time allows... Seem to remember trying those transistors years ago in an audio application and they didn't work well---now know that's not what they were made for ! Of course, am keeping the original transistor with the electrolytics in case a future owner wants to return it to original state...

Now need to finish cleaning/polishing and reassemble !

Pics below---original, the GE replacement, and completed chassis...

John


Attachments:
ARF 66T1 ORIGINAL CONV TRANS.jpg
ARF 66T1 ORIGINAL CONV TRANS.jpg [ 228.94 KiB | Viewed 1079 times ]
ARF 66T1 CONV TRANS REPLCMNT.jpg
ARF 66T1 CONV TRANS REPLCMNT.jpg [ 224.88 KiB | Viewed 1079 times ]
ARF 66T1 CHS COMPLT.jpg
ARF 66T1 CHS COMPLT.jpg [ 227.77 KiB | Viewed 1079 times ]
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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Tue 19, 2017 6:47 pm 
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Location: Mount Pleasant UT 84647 (from Coventry, UK)
Good news!


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Thu 21, 2017 3:13 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Hey Colin---was very thankful that I had that transistor ! The frequency shifted a bit and had to adjust the IF's a bit to regain performance, so really need to give this a "proper" alignment...

Progress continues...

After completing the cleaning of cabinet interior yesterday evening, carefully and thoroughly polished the chrome tonight with Mothers Chrome Polish. Also carefully wet-sanded the top of handle which had several scuffs and scratches with 2000 grit sandpaper which I've found works perfectly with many plastics prior to polishing several rounds with Novus-2. Looks much better ! Installed chassis into cabinet with hope of finishing this set before weekend time with family.

Gettin' closer !

Few pics below---handle had not been polished at this point...

John


Attachments:
ARF 66T1 CAB CLN INS.jpg
ARF 66T1 CAB CLN INS.jpg [ 222.83 KiB | Viewed 1048 times ]
ARF 66T1 CAB CLN EXT.jpg
ARF 66T1 CAB CLN EXT.jpg [ 162.69 KiB | Viewed 1048 times ]
ARF 66T1 CHS CMPLT FRT.jpg
ARF 66T1 CHS CMPLT FRT.jpg [ 201.2 KiB | Viewed 1048 times ]
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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Fri 22, 2017 3:42 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Completed this radio tonight except for performing a complete "proper" alignment and finding a felt washer to put between tuning knob brass disk and cabinet to hold disk closer to warped plastic knob. The brass disk was badly tarnished in areas and had to clean it with ultra-fine Scotchbrite and water to bring back shine---went over it several times with Novus-2 to remove as much as the fine scratching as possible which made it look much better.

Since the grille was painted black, decided to try and touch-up bad areas with a black Sharpie---took a little time and patience, but turned out pretty well for a temporary "fix" !

Since the battery compartment label was damaged by leakage and couldn't easily replace, cut a small strip of thin, clear flexibile plastic saved from merchandise packaging which fit between holder mounting tabs and slid it beneath---this will preserve the paper from further damage when installing/removing batteries.

Pictures below... Last one showing examples of all three of Motorola's first transistor radios---56T1, 66T1, & 76T1.

John


Attachments:
1ARF 66T1 PRTS CLND-POLSHD.jpg
1ARF 66T1 PRTS CLND-POLSHD.jpg [ 233.64 KiB | Viewed 1033 times ]
2ARF 66T1 CMPLT.jpg
2ARF 66T1 CMPLT.jpg [ 174.38 KiB | Viewed 1033 times ]
3ARF 56T1 66T1 76T1.jpg
3ARF 56T1 66T1 76T1.jpg [ 202.17 KiB | Viewed 1033 times ]
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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Fri 22, 2017 7:08 am 
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^Nice family ya got there, John!

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\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Fri 22, 2017 11:35 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1050
Location: Palos Verdes, CA
John - Your collection of vintage Motorola transistor radios looks great! - Mark


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Sat 23, 2017 4:27 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks much, Guys !

Far from perfect, but clean & working ! Sure glad to finally have this trio of firsts (also have a 76T2 in family room display case)...

John


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Sat 23, 2017 4:46 am 
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John, take a look at the Admiral in this thread, and tell me that it's case doesn't look like your larger Motorola;
viewtopic.php?f=4&t=332424

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\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Sat 23, 2017 4:59 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5274
Location: Indianapolis, IN
Hey Richard,

Did see that and your set in Frank's thread---wonder if Admiral got the idea of metal cabinet and rotating antenna from Motorola ? Motorola also had several tube portables with that set-up...

John


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Sat 23, 2017 5:39 am 
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Those early Texas Instruments transistors can be hard to find replacements for, so it's good you happened to have something suitable. It's interesting that the grill is hard steel instead of the usual aluminum (or other soft metal), but I'd say your sharpie touch up looks good.
I have one of these still in the box somewhere, in used and non-working condition; if I'm remembering right, the previous owner spun the handle all the way around a few times and tore up the antenna wires, so I will probably need to find a replacement antenna assembly if I ever want to fix it. :?


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Dec Sun 24, 2017 1:52 am 
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xrhonda91 wrote:
Hey Richard,

Did see that and your set in Frank's thread---wonder if Admiral got the idea of metal cabinet and rotating antenna from Motorola ? Motorola also had several tube portables with that set-up...

John

I think it would be a matter of verifying which came out with that style of cabinet first, to determine who copied whom.

Yes, the early Transistor "lunchbox" radios from several makers did indeed appear to use the cabinets made for tube sets; I have a Dewald Transistor, and a Westinghouse tube portable, that each used the same basic cabinet for both, with minor changes to the dials and grill cosmetics.
50sTransistorRadios wrote:
Those early Texas Instruments transistors can be hard to find replacements for, so it's good you happened to have something suitable. It's interesting that the grill is hard steel instead of the usual aluminum (or other soft metal), but I'd say your sharpie touch up looks good.
I have one of these still in the box somewhere, in used and non-working condition; if I'm remembering right, the previous owner spun the handle all the way around a few times and tore up the antenna wires, so I will probably need to find a replacement antenna assembly if I ever want to fix it. :?

I've done more than a few 56T1/66T1/6X31 sets, including one or two that needed the antenna leads reconnected.
All you need to do is pull the wiring on each side out slightly, to be able to solder leads on them long enough to be connected to where they need to go on the PCB.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Jan Thu 18, 2018 2:19 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5274
Location: Indianapolis, IN
Got this radio properly aligned this evening using a recently built tone modulated, crystal-controlled 455 kHz oscillator: viewtopic.php?f=12&t=334241

1st IF adjustment very broad with no real "peak", so wonder if transistor weak ? But it does work fairly well now...

John


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Jan Sat 20, 2018 4:45 am 
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Joined: Jan Sun 29, 2017 6:55 pm
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An alternative to the high priced NTE 101 replacement could be the Soviet made transistors which are available on Ebay. For example the GT311, germanium NPN, 12V Vce, fT >300Mhz.
Here is the datasheet http://www.5v.ru/ds/trnz/gt311.htm


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Jan Sun 21, 2018 5:23 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5274
Location: Indianapolis, IN
Thanks solderblob---I've looked at those on Ebay, but just feel uneasy about them even though others have had success... Guess it's difficult to get over that old idea that Soviet parts were of sub-standard quality...

John


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 Post subject: Re: The Motorola 66T1 --- long sought project...
PostPosted: Jan Wed 24, 2018 6:30 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1050
Location: Palos Verdes, CA
John - At least your Motorola 66T1 works as the one I have only picks up one station! As for NTE transistors, I've found that sometimes they work well as replacement transistors, and sometimes they don't, for whatever reason. I have a RCA 7-BT-9J transistor radio where the previous owner had replaced a 235 transistor with a RCA 268A transistor. According to the transistor cross reference website, a NTE 126 should work as a replacement for the 235 transistor, but the radio worked better with the RCA 268A, although it only picked up a few stations. As the RCA 7-BT-9J has plug-in transistors, I decided to replace the 234 transistor with a RCA 268A that I had, and now the radio works great! - Mark


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