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 Post subject: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sun 16, 2020 1:37 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Hello All,

So far, I've not been able to find a junk chassis so that I could restore my "basket-case" Raytheon 8TP-2 and had been thinking of using some of the parts to build a temporary, easily undo-able, usable "frankenradio". I've had a cheap, rough Philco T64-124 with a tight tuning cap for quite awhile that I bought with the idea of using the chassis with a vernier tuner to make another radio. It's an outstanding performer and has very good sound quality for it's size, so would be great for a fine project.

Do have the top, aluminum section of original 8TP chassis which has vernier-drive tuning cap, ferrite-loopstick antenna, and volume control. Carefully removed the Philco ferrite-rod and tuning cap from its PCB and temporarily connected the 8TP components with short jumpers. After playing with the OSC & ANT trimmers, was able to get it working fantastically on the high end of band and sound was excellent with test speaker. The low end of band was way off and the Philco oscillator coil didn't have enough adjustment to align which I thought might happen since capacitance of tuner OSC gang most likely different---am going to play with a "padder".

Now need to find a volume control with a two-section power switch for the Philco OTL output. Plan to power this "concoction" with two "D" cells instead of the penlite batteries since I'm going to install a larger speaker and use the radio more often. Fortunately, this Philco design uses a standard 8 Ohm impedance which will make that easier...

Absolutely nothing on either radio will be "irreversibly" modified or harmed---both can be returned to original if & when I find an original chassis for the Raytheon.

Now on to the "drawing board" to design a temporary plastic chassis which will hold all the pieces in their proper places so radio can be regularly used...

Below is a pic of the "basket-case" parts after I sorted and organized them---project pics will be posted when able...

Any comments on this somewhat crazy idea ?

John


Attachments:
13ARF 8TP2 BASKET CASE.jpg
13ARF 8TP2 BASKET CASE.jpg [ 711.62 KiB | Viewed 1719 times ]


Last edited by xrhonda91 on Feb Fri 28, 2020 10:07 pm, edited 1 time in total.
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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Sun 16, 2020 7:11 pm 
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Joined: Aug Wed 26, 2009 1:50 am
Posts: 1602
Location: Mesquite NV 89027 (from Coventry, UK)
I look forward to seeing the end result. I know it will be good!


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 2:47 am 
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Joined: Jan Tue 31, 2012 1:55 am
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Location: Mountains of Mourne. Ireland.
Tupperware... :)

Greg.


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 4:24 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Tupperware ???


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 4:25 pm 
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Joined: Sep Fri 07, 2007 2:27 am
Posts: 6382
Location: Grand Chute, Wisconsin
Here you go, John.

https://www.dropbox.com/sh/0a13gvxmybax ... rvwza?dl=0

This is the Sams 292-9, the pages in the TSM-2 were identical.

I'm looking forward to seeing what this project becomes!

.


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 6:52 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Hey Jim,

Thanks very much for the excellent hi-res scans ! That will really help with my research and when I find an original chassis to rebuild... So far I've seen three different chassis on-line---the first with 8-transistors, the 2nd with 7-transistors using threaded mounting stud IFT's and a 3rd with clip-retained IFT's. Looks like they were rapidly looking to cut costs on their first radio !

Am taking care of Mom for a few days while sister is away, so this project is waiting on worktable at home. Have the necessary materials except for power switch and am debating using another audio circuit to eliminate need for dual contacts.

Maybe I'll be able to find an original, junked chassis before then and be able to restore this properly !

John


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 7:53 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1498
Location: Palos Verdes, CA
John - Since you have a Raytheon 8TP, I would think that you could build a replica chassis, based on your experience and skill level. As you already have most of the original components, you could just use replacement transistors instead of trying to find the original Raytheon units. - Mark


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 8:31 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Hey Mark,

I've been thinking about that too, and maybe making a plexiglass chassis so that components could be seen on bottom side. Have various pieces stashed in garage...

Still want an original chassis if I can ever find one, but a plexiglass panel with original parts would look kinda neat... Got a drill press now which would make fabrication easier. Could use all silicon transistors...

Would definitely be a bigger challenge and much more interesting than adapting the Philco PCB...

John


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Mon 17, 2020 11:11 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1498
Location: Palos Verdes, CA
John - As you posted photos of the prototype Raytheon 8TP that had a plexiglass case, I think making the chassis out of plexiglass would be a neat project! - Mark

I also found an interesting posting on restoring a Raytheon transistor radio, which I thought you might find interesting:

https://www.geojohn.org/Radios/MyRadios ... ay7TP.html


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 Post subject: Re: Raytheon 8TP-2 temporary "frankenradio" project...
PostPosted: Feb Sun 23, 2020 2:39 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Thanks for the link, Mark---found that interesting story awhile back.

After giving this "temporary" project some thought, realized it would be much more interesting to use the original components that came in the "basket-case" and fabricate a chassis. Mark's post gave me the "nudge" that helped change my mind...

Decided that the plexiglass would be too difficult to work with, so am making chassis out of 3/16" thick white styrene-type plastic. It was scrap from 1st company I worked for and was used to make side panels for their blood-serum analyzers. Very easy to work with as you only need to deeply score with utility knife and "snap off" excess. Drills easily, also...

Since the sides of cabinet are sloped, the chassis is wider at bottom than top which made measuring and cutting just a bit more time-consuming. Simplified it a bit by just cutting out corner by volume control instead of slotting like original---will relocate the audio driver transistor which is on the "tab" of factory chassis...

Now need to make a drilling template for IFT's, oscillator coil, and audio transformers. Am still debating on whether or not to use round transistor sockets due to space requirements (originals are rectangular which would be difficult to cut holes for).

Since it appears that the IFT's are the identical parts used in the original 8-transistor design with a 2nd IF amplifier stage and transistor detector, am going to build this chassis using that circuit. Should be a much better performer !

Below is a picture of chassis which I just cut and sanded edges of this afternoon along with a pic of the 1st experiment using the Philco T64 PCB which will now be available for another project...

Does anyone have a hi-res picture of the 8-transistor chassis bottom (wiring side) ??? Unfortunately, the schematics have no pin-outs for the IF transformers... Also need to find three 390 pF silver-mica caps since these were missing from parts bag...

Stay tuned !

John


Attachments:
ARF 8TP-2 TEMP IDEA1 W-T64 CHS.jpg
ARF 8TP-2 TEMP IDEA1 W-T64 CHS.jpg [ 635.97 KiB | Viewed 1494 times ]
ARF 8TP-2 TEMP PLASTIC CHS 2-22-20.jpg
ARF 8TP-2 TEMP PLASTIC CHS 2-22-20.jpg [ 257.51 KiB | Viewed 1494 times ]
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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 5:17 pm 
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Joined: Aug Thu 23, 2018 1:11 pm
Posts: 43
If finding a volume control pot with double-pole switch proves difficult, a work-around may be to use the single-pole switch to control the positive power rail, and a small NPN transistor with its base controlled by the positive rail to switch the negative rail. A small relay would also be a possibility for creating the second switching function.

You must really love that radio to go to such lengths to get it going! Good luck!


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 5:52 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Thanks much for suggestion, John, but decided to build chassis with most of the original Raytheon components from "package". Completed it "mechanically" yesterday and now have to gather needed parts to wire it. Am now working on post with pictures to hopefully submit within a few hours.

John


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 7:49 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Hello All,

Finally completed the fabrication of chassis and mounting brackets needed for this project yesterday.

Had to trim panel corners and cut slot to obtain necessary clearances for installation into cabinet and then carefully round edges with sandpaper. Installed upper aluminum controls sub-chassis and positioned plastic panel inside cabinet to mark lower mounting screw holes. Through front grille opening (grille & backing removed for cleaning) used curved-tip hemostats clamped onto a short nail to mark hole locations from back side of cabinet mounting brackets. After holes center-punched and drilled, installed panel with proper screws and checked alignment. Marked position of plastic panel upper edge on aluminum, then disassembled to attach a cut-off section of old aluminum PCB stiffener bar which already had 4-40 tapped holes along its edge. Carefully marked necessary position then taped the bar securely in place to mark mounting hole locations using existing holes on original sub-chassis. Drilled, de-burred, and mounted bar in place using appropriate hardware. Carefully marked the five hole locations on top edge of plastic panel using a nail which fit bar holes snugly, then drilled and mounted. Installed into cabinet to verify fit and alignment and all was fine. Now removed plastic panel so that component mounting holes could be marked and drilled. Used painter's tape to lay out locations, then used nail for punch. Even using drill-press, the bit caught the edge of these "punchings" and several holes were slightly off-center and had to be "wallered" with a hand drill for proper component fit---should have taken the time to find the correct punch ! Carefully cleaned/removed all markings from sub-chassis & panel...

Made a small aluminum bracket to attach oscillator coil and cut down a sturdy steel angle and modified for speaker mounting.

Altered the location of the audio circuit components to make it easier to wire since I planned to use a 4-"AA"cell holder for power.

The front grille had some denting, so removed and carefully rolled smooth from the inside using a large socket-wrench socket on flat, smooth surface. It also appeared to have had a small scrape which somebody had sloppily sprayed with gold paint that also went through perforations and collected on the heavy fish-paper backing. Carefully used lacquer thinner to removed this mess which covered a much larger area than the "scuff". Grille looks MUCH better now, as the paint made it appear somewhat dull and dirty.

The final picture below is a "preview" of what completed chassis may look like---am planning now on trying some NOS 2N930 NPN silicon transistors in this circuit by adjusting bias, removing IF neutralizing caps, reversing power supply polarity and whatever else may be necessary. But also am considering pressing some quality pin-sockets into panel and using Japanese transistors from a junked radio...

None of the Raytheon parts were altered or modified in any way so that radio could be returned to stock if an original chassis is ever found...

Stay tuned !!!

John


Attachments:
ARF 8TP2 PANEL PROCESS.jpg
ARF 8TP2 PANEL PROCESS.jpg [ 271.96 KiB | Viewed 1382 times ]
ARF 8TP2 CHS PROG1.jpg
ARF 8TP2 CHS PROG1.jpg [ 435.66 KiB | Viewed 1382 times ]
ARF 8TP2 CHS PROG2.jpg
ARF 8TP2 CHS PROG2.jpg [ 281.32 KiB | Viewed 1382 times ]
ARF 8TP2 CHS PROG3.jpg
ARF 8TP2 CHS PROG3.jpg [ 479.04 KiB | Viewed 1382 times ]
ARF 8TP2 CHS PREVIEW.jpg
ARF 8TP2 CHS PREVIEW.jpg [ 518.54 KiB | Viewed 1382 times ]
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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 8:25 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1498
Location: Palos Verdes, CA
John - Wow, your "replica" chassis is impressive! Can't wait to find out how it performs. - Mark


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 8:27 pm 
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Joined: Nov Wed 14, 2007 11:37 pm
Posts: 1625
Pretty amazing work!


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Feb Sat 29, 2020 11:47 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Thanks much, Guys !

Printed out parts lists and schematics to study. Hope to start wiring next week. Going to require some experimenting to get the biasing right on the silicon transistors, so will start at the front end and work through it stage-by-stage...

John


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Mar Sun 01, 2020 12:26 am 
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Joined: May Sun 26, 2019 4:25 pm
Posts: 37
wOWZERS!
Engineering a copy of a Raytheon 8TP-2 ?!?!?

Looking real good sir!
I have a question (or four). Why aren't you sourcing original Raytheon transistors?
Too expensive? Too rare? Too hard to find ones that still work?

I think that some sapphire blue oval and square cans would be uber-impressive to gaze upon.
Just my 2 centavos amigo. :)


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Mar Sun 01, 2020 5:29 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Thanks Zenettesky !

Actually have a couple "once NOS" CK760's & a used CK766A, but want to make this "temporary" chassis the best performer I possibly can using the parts that were stripped from original along with the silicon transistors I have on hand. If I ever find an original chassis, would consider populating it with the proper Raytheon transistors if I can find them at decent prices... I totally agree that the Raytheon blue-ovals are real eye-catching beauties !

John


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Mar Sun 01, 2020 5:22 pm 
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Joined: Aug Wed 26, 2009 1:50 am
Posts: 1602
Location: Mesquite NV 89027 (from Coventry, UK)
Excellent work John.


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 Post subject: Re: Raytheon 8TP-2 "temporary" home-made chassis project...
PostPosted: Mar Mon 02, 2020 2:26 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6351
Location: Indianapolis, IN
Thanks Colin !

Beautiful weather today, so spent time outdoors---but did get the grille, knobs, and exterior brass trim pieces cleaned. Decided not to polish the brass hardware and leave it as it was once clean to maintain "character"...

Pic below of clean items ready to be reinstalled...

More to come !

John


Attachments:
ARF 8TP-2 PRTS CLN.jpg
ARF 8TP-2 PRTS CLN.jpg [ 787.92 KiB | Viewed 1290 times ]
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