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 Post subject: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Tue 25, 2020 3:08 am 
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Location: Palos Verdes, CA
A few years ago, I bought a Raytheon 8TP-2 transistor radio that was for sale on eBay that the seller said it did not work. I could see that one of the transistors was missing and the rest had been replaced, with the exception of one Raytheon transistor. When I got the radio and removed the chassis from the case, I found out that someone had replaced all of the transistor sockets! The new transistors were the correct type, so I had a NTE100 transistor to replace the missing Raytheon CK760 and was disappointed when all I got was static. I tried replacing all the transistors with other transistors that I had collected over the years, but could not get the Raytheon 8TP to work. I was looking for parts for another radio today and found that I had a Lafayette 6 transistor radio in poor condition, but it had GE plug-in transistors. I tried the GE transistors that could replace the CK760, but all I still got was static. There were also 2 GE 2N188A transistors in the Lafayette, but these were equivalent to a NTE102 transistor. Figuring that I had nothing to lose, I plugged-in the 2N188A transistor and to my surprise, the Raytheon 8TP-2 worked great! Since the radio now works, it would be nice if I could find all the original type blue Raytheon transistors, but they would probably cost more than what I paid for the radio originally!


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Raytheon 8TP-2 transistor radio 2.JPG [ 112.64 KiB | Viewed 646 times ]
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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Tue 25, 2020 6:02 am 
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Congrats on getting it working again, and interesting that it does so with the original paper caps, of which there seem many!

You can probably eventually get the blue Raytheon's by keeping an eye on eBay, and acquiring them one by one over time. The only trouble is, Germanium Transistors can eventually start giving up the ghost as they age.

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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Tue 25, 2020 11:45 pm 
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Joined: Aug Sat 16, 2014 2:19 am
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Location: Palos Verdes, CA
I checked the serial number of the Raytheon 8TP-2 with the replaced transistor sockets and it probably had the black Raytheon CK718 transistors that I believe were soldered into the sockets as I have another 8TP-2 with a later serial number that also has the black transistors. The previous owner could have tried to replace some of the transistors and ended up damaging the sockets and then decided to replace them.


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Wed 26, 2020 12:23 am 
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Joined: Sep Tue 15, 2015 1:16 am
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Location: 18424 PA
fifties wrote:
Congrats on getting it working again, and interesting that it does so with the original paper caps, of which there seem many!

You can probably eventually get the blue Raytheon's by keeping an eye on eBay, and acquiring them one by one over time. The only trouble is, Germanium Transistors can eventually start giving up the ghost as they age.



No they don't. Under poor storage conditions, maybe, but so will a tube or silicon transistor for that matter. Corrosion will start on the leads.


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Wed 26, 2020 4:30 am 
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n3uvt wrote:
fifties wrote:
Congrats on getting it working again, and interesting that it does so with the original paper caps, of which there seem many!

You can probably eventually get the blue Raytheon's by keeping an eye on eBay, and acquiring them one by one over time. The only trouble is, Germanium Transistors can eventually start giving up the ghost as they age.



No they don't. Under poor storage conditions, maybe, but so will a tube or silicon transistor for that matter. Corrosion will start on the leads.

Yes they will. It happened to more than one Transistor I've had since the '50's. I've heard that they grow tin whiskers inside.

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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Wed 26, 2020 5:09 am 
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Location: Indianapolis, IN
Hey Mark,

Glad you got it working ! Am surprised that the 2N188A audio transistor worked well as the converter/mixer as that stage is often finicky in some sets... May have to try one in mine out of curiousity !

John


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Wed 26, 2020 8:05 pm 
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Joined: Aug Sat 16, 2014 2:19 am
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Location: Palos Verdes, CA
John - I looked at my notes when I purchased the Raytheon 8TP-2 and found that it was missing the CK-759 (converter transistor) and the CK-760 (IF amp transistor). I originally used NTE-100 transistors as replacements, but only got static. The transistor sockets that the previous owner used had 5-pin sockets, except for the converter and oscillator transistors, which only had 3 pins. Having sockets made it easier to replace the transistors, but I did break-off one of the leads off a spare Raytheon CK-760 transistor, which made me decide not to remove Raytheon transistors from other radios I own in an attempt to get the 8TP-2 working. - Mark


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Feb Wed 26, 2020 9:00 pm 
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Glad you got it working.


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Mar Mon 23, 2020 1:34 am 
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Joined: Aug Sat 16, 2014 2:19 am
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Location: Palos Verdes, CA
I have another Raytheon 8TP-2 7 transistor radio and although the label says that the radio uses CK721 transistors, the 1st audio amp was changed to a Raytheon 2N133, with the 2nd audio amp using a 2N130, with both audio output transistors using 2N138 transistors, all which are the smaller blue Raytheon transistors. This Raytheon 8TP-2 does perform better than the radio using the CK721 transistors. - Mark


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 Post subject: Re: Raytheon 8TP-2 with replaced transistor sockets
PostPosted: Mar Mon 23, 2020 2:37 am 
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Joined: Sep Tue 15, 2015 1:16 am
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Location: 18424 PA
Only a few type grew tin whiskers, none were US made as far as i know. I do have some bad ones i saved but i forget what the failure was. I very much doubt tin whiskers was the major failure mode. Most likely a poor seal or corroded leads going into the case.
https://nepp.nasa.gov/whisker/anecdote/ ... index.html

As i said, storage conditions are probably the main factor in them not working.


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