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 Post subject: GE P-1810A project...
PostPosted: Jan Mon 02, 2017 4:12 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 4458
Location: Indianapolis, IN
Have one of these in the "pipeline" and wondered if anyone had the service info and would share it ?

From pics, it appears to have a tuned-RF amp stage and has 10 transistors.

Also would like to hear of anyone's experiences with these sets...

Seller claims it is dead---hopefully caps or something simple, but would like to have info "just in case" and to see how those 10 transistors are being utilized...

Thanks much !
John


Last edited by xrhonda91 on Jan Fri 06, 2017 3:10 am, edited 1 time in total.

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 Post subject: Re: Anyone have service info for GE P-1810A to share ?
PostPosted: Jan Mon 02, 2017 4:49 am 
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Joined: Jan Tue 31, 2012 1:55 am
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Location: Mountains of Mourne. Ireland.
Hey John, it was covered in Sams TSM 65 January 1966
Unfortunately I don't have it.

http://i.ebayimg.com/00/s/MTA2NlgxNjAw/z/uUUAAOSwNSxVUgiB/$_57.JPG

Greg.

oh... Happy new year... :)


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 Post subject: Re: Anyone have service info for GE P-1810A to share ?
PostPosted: Jan Mon 02, 2017 2:58 pm 
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Joined: Sep Fri 07, 2007 2:27 am
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Location: Grand Chute, Wisconsin
I'll be able to scan and post it this afternoon...

.


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 Post subject: Re: Anyone have service info for GE P-1810A to share ?
PostPosted: Jan Mon 02, 2017 4:57 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks much Greg & Jim !

Wish all a Good 2017 !

John


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 Post subject: Re: Anyone have service info for GE P-1810A to share ?
PostPosted: Jan Mon 02, 2017 8:23 pm 
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Joined: Sep Fri 07, 2007 2:27 am
Posts: 4577
Location: Grand Chute, Wisconsin
You're welcome.

https://www.dropbox.com/sh/smnxk8a484ah ... lmyRa?dl=0

Enjoy!

.


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 Post subject: Re: Anyone have service info for GE P-1810A to share ?
PostPosted: Jan Mon 02, 2017 9:32 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Hey Jim,

Just downloaded the images---excellent hi-res scans ! Sure appreciate your effort---thanks again !

Neat to see the model page---actually had the P-1820A AM/FM version many years ago, but gave it away...

Kinda "chintzy" for GE to use two transistors as bias regulator diodes, but guess that was towards the end of the transistor-count "wars" and they wanted to make an impression...

Wonder if this will be of the same caliber performance-wise of other GE tuned-RF amp equipped sets of that era ?

John


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Fri 06, 2017 3:16 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Radio arrived today and not as good as it looked in Ebay pic---dents in grille and small dings in tuning knob bright like someone stabbed at it multiple times with ball-point pen...

And---someone had ripped the oscillator coil of off PCB (see below) !!! No inside pics in listing, but never expected this...

John


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Ebay P-1810 osc coil torn out 1-5-2017.jpg
Ebay P-1810 osc coil torn out 1-5-2017.jpg [ 236.23 KiB | Viewed 936 times ]
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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Fri 06, 2017 3:43 am 
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Location: Mountains of Mourne. Ireland.
Sometimes you eat the bar, and sometimes... well, he eats you.

:) Greg.


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Fri 06, 2017 5:31 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Shouldn't be too difficult to harvest another osc coil from a junked Transistor set.

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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sat 07, 2017 2:29 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Now need to find what cheap, undesirable GE sets use that same oscillator coil !

SAMS says the GE part number for it is: RT-1069

Anyone recognize that number ???

Thanks !

John


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sat 07, 2017 3:55 am 
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John, what makes you think that it's any different than any other garden variety Transistor radio oscillator coil? I would just grab one from any Transistor donor and try it.

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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sat 07, 2017 11:50 pm 
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Mitch


Last edited by PBPP on Jan Tue 10, 2017 10:02 pm, edited 1 time in total.

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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 4:33 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks for the info, Mitch...

I had one new oscillator coil of same size with the pinout of the low & high impedance sections (either side of tap) of primary reversed. I tacked it in wiring as it should be and it barely worked---only able to receive the two strongest stations and couldn't even align them to proper locations on dial, so these are not all the same ! Maybe for the cheapo, handheld portables they made a zillion of...

Maybe, just maybe someone will have one of these radios in a junk-box...

Not doing well lately radio-wise---the T-81H was trashed by someone probably using an incorrect wall-wart...

John


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 6:09 am 
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Hey John,
Go to the Archives and look at Elements of Radio servicing, I think it's chapter 14 dealing with oscillator coils. He discusses the procedures needed if an exact replacement isn't available. Even though the subjects are tube radios, the principles would be the same.

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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 4:46 pm 
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Joined: Jul Wed 22, 2009 3:07 pm
Posts: 590
Hi John,

You could try modifying the osc coil that you have, you can not loose much.
Your problem seems to be that the "run of the mill" oscillator coils are for the small polyvaricon caps, and those have about 80pF - 90pF final capacitance at the oscillator section.
In your radio, judging from the oscillator padding capacitor, C8 390pF, it looks that the oscillator section in the variable cap has about 360pF final capacitance. That means about 180pF - 200pF final capacitance for the oscillator. (You could also just measure it, if you have the tools for that!)
For that capacitance the coil is too much, that is the reason the dial does not line up, and the sensitivity is off as the antenna and RF stages can not be tuned up for that osc coil.
The generic osc coils have 360uH inductance, from datasheets of osc coils and IF coils:
http://www.electronics-tutorials.com/filters/if-amplifier-transformers.htm
For 180pF you would only need about 140uH inductance.
With about 110 turns for 360uH, you would need only about 70 turns for 140uH.
You could try removing wire from the existing osc coil if you manage to disassemble it.
Usually the largest winding is on the outside, so just find the wire ending at the outside and remove the turns. The coils I played with it the winding was secured with bees wax, and despite the thin wire, I could remove turns. To tell the truth, that was only one turns, the wire end was broken in the coil!
I would not worry about the changed turn ratios, the oscillator circuit is quite tolerant to that.
If the wire removal turns into a "disaster", you could try to rewind it.
Here are my adventures:
http://antiqueradios.com/forums/viewtopic.php?f=4&t=197891&p=2226186&hilit=philips#p2226186

Good luck, Peter


Last edited by orbanp on Jan Sun 08, 2017 5:12 pm, edited 1 time in total.

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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 5:09 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 4458
Location: Indianapolis, IN
Thanks Richard---have seen you refer to that resource before, might be interesting info...

And thanks much, Peter, for the detailed analysis and information ! Think I'll put this radio on hold for awhile to see if I can find the proper part, but will keep your post in mind. I don't have an LCR meter, but it would be a handy tool. I've repaired broken connections in these small coils, so guess I could try removing some turns if necessary...

John


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 5:35 pm 
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Joined: Jul Wed 22, 2009 3:07 pm
Posts: 590
Hi John,

Just another thought!
Instead of changing the oscillator coil, you could change the oscillator padding capacitor!
From quick calculations, try 120pF for C8.
You also might need to change (decrease) the value of C11.
This might affect the accuracy of the tracking, but I think it is worth a shot.

Peter


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 5:51 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks Peter !

John


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Sun 08, 2017 6:16 pm 
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Joined: Sep Sat 29, 2012 6:32 pm
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Location: Endicott, NY
I would bet it was a kid that snapped off the oscillator coil, although perhaps some adult broke it while trying to adjust it. In any case, I hope you can find a replacement.


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 Post subject: Re: GE P-1810A project...
PostPosted: Jan Mon 09, 2017 12:22 am 
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orbanp wrote:
judging from the oscillator padding capacitor, C8 390pF, it looks that the oscillator section in the variable cap has about 360pF final capacitance.

Hmm, interesting. If that's the case, then an osc coil from an AA5, many of which used tuners in the 350-405 mFd range, might work.
John, if you have a junked AA5 from which you could harvest the coil, you might try that.

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