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  #16  
Old 04-08-2015, 07:03 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by Gregb View Post
I really don't remember a brand, the case was a brown plastic.

Gregb
The Kelvin kit I have didn't have the transistors included. I looked at the bill of material and it didn't show the transistors. Seemed strange! The schematic shows all germanium types and it has a revision date of 1997.
I personally don't get it! The instructions stated to check to see that all the parts were present, but didn't show the transistor types.
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  #17  
Old 04-09-2015, 07:12 PM
centralradio centralradio is offline
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I have pieces of the Radio Shack 8 transistor radio 28-222 that I got as a gift back around 1977 with the white or tan/brown case.As I found it a couple years ago with the PC board broken and parts missing .What a shame.For some reason I never completed the kit when I got it.

For some reason these current kits look cheesy to me as I compare them to the old Radio Shack 28-222 kit.

As years went by around 1983 I picked up the cheaper Radio Shack 28-4029 radio kit model in the black case with 2 transistors and a LM386 for the audio amp .It sucks compared to the original kit.

As I was doing alittle homework on these kits the other day .I found a couple posts on ARF about the Graymark version of the old Radio Shack kit .The model number is or was Graymark AM radio model 536.

I would love to get my hands on one of these Graymarks.

http://www.antiqueradios.com/forums/...p?f=4&t=196521

http://www.esssales.com/graymark/ele...js-s4-500.html

The 1970's RS radio kit had these plastic style transistors like in the photo in the attachment and not the old metal germ 2sb54-2sb56 style transistors.
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  #18  
Old 04-10-2015, 07:27 AM
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captainmoody captainmoody is offline
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I'd love to have back my RS Archerkit AM radio I assembled in '74.. It got traded off that Summer. I was just an 11 year old kid and more interested in tube radios then.

That Graymark one might be tempting though..!
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  #19  
Old 04-10-2015, 10:50 AM
centralradio centralradio is offline
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Originally Posted by captainmoody View Post
I'd love to have back my RS Archerkit AM radio I assembled in '74.. It got traded off that Summer. I was just an 11 year old kid and more interested in tube radios then.

That Graymark one might be tempting though..!
Yea .I'm close to your age Capt .I like to check out the Graymark kit out since its a clone of the 1970's RS radio.They must of bought the rights from the Shack to continue with it.

Maybe somebody can chime in with any more info on the Graymark kit and obtaining one.
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  #20  
Old 04-10-2015, 08:24 PM
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compucat compucat is offline
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Quote:
Originally Posted by centralradio View Post
Yea .I'm close to your age Capt .I like to check out the Graymark kit out since its a clone of the 1970's RS radio.They must of bought the rights from the Shack to continue with it.

Maybe somebody can chime in with any more info on the Graymark kit and obtaining one.
In high school, 1983 I built the Graymark AM radio kit. In class we built it on the included breadboard and after I took it home, I built it on the pic board and installed it in the cabinet, all included. It was a well built radio and a good performer. The kit is still available today just as it was and I have thought of building one for nostalgia purposes.
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  #21  
Old 05-04-2015, 08:54 PM
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Dave A Dave A is offline
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I got the 6 transistor version today. It took me an hour to figure out some of the mystery connections. I have reached out to my Chinese friends for help with translation of the instructions.

My easiest guide to assembling is to find the 3v+ rail and mount parts from there. The xfmr was figured by ohming the pins as it can be mounted backwards. Electros are short wire as minus. LED is short wire as minus. Xstrs are marked. Small caps are marked. You just have to search the board for all the parts. Get your resistor guide nearby. I had a problem with the ferrite coil until I ohmed it and figured out the long side and the short side. A/B/C/D on the instructions. Battery mount can be any direction with the +/- and black/red as needed. There are still two yellow wires I have not figured out.

I stand to be corrected.
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Last edited by Dave A; 05-04-2015 at 09:35 PM.
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  #22  
Old 05-04-2015, 09:47 PM
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maxhifi maxhifi is offline
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I got mine today too! The IF and oscillator coils were hard to tell apart until I realized the oscillator has no cap in the bottom. The audio transformer has a dot on it to indicate which way it installs but it sure isn't obvious. Aside from having the world's worst speaker I am happy with mine.

Yellow wires are for the speaker. The B+ dropping reaistor is marked on the board as 100k, but it really is 100 ohms and is also correct on the schematic. The board has several little solder bridges which have to be closed to allow it to work, presumably for measuring current to assist students to troubleshoot.
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Last edited by maxhifi; 05-04-2015 at 09:52 PM.
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  #23  
Old 05-04-2015, 11:22 PM
Gregb Gregb is offline
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I bought both the IC radio and the transistor set. I have received and built the IC version and it works ok but not really very good. The AM works much better than the FM, gets all the local stations with good volume.

Gregb
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  #24  
Old 05-05-2015, 08:02 PM
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Dave A Dave A is offline
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Max,

Help me out.

I figured the coils.
My xfmr has no dots in sight. Where do I look.
What is the number of the B+ dropping resistor.
Where are the bridges to close?

Can you list a revised/corrected construction guide? I am close but the rest of us could use the help.

Dave A
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  #25  
Old 05-05-2015, 08:26 PM
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maxhifi maxhifi is offline
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R6 is marked 100K on the board and is really 100 ohms
The tip of my pen is pointing at the dot on the transformer, on mine it's a little raised bump so much as a dot. I ohmed out the windings on mine before I installed it and noticed the dot after. The board has a corresponding dot. The next message will show solder bridges A B C and D. Presumably students would use them to measure current of the various sections as per the X's on the schematic as a troubleshooting aid.
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Last edited by maxhifi; 05-05-2015 at 08:39 PM.
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  #26  
Old 05-05-2015, 08:27 PM
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maxhifi maxhifi is offline
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Here are the solder bridges
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  #27  
Old 05-09-2015, 11:14 PM
k2glo k2glo is offline
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I picked up two KELVIN transistor radio (kits?0) this week. Both have the same transistor line-up. 2N412 osc, two 2N410 in the IF's, 2N408 AF Driver, and 2N3906 Push-Pull AF outputs.
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  #28  
Old 05-10-2015, 09:14 PM
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Dave A Dave A is offline
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Max, a few questions.

Do I have to solder the bridges for it to work?
Did you have to tune the coils?
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  #29  
Old 05-10-2015, 09:31 PM
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maxhifi maxhifi is offline
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Max, a few questions.

Do I have to solder the bridges for it to work?
Did you have to tune the coils?
Yes and yes. Do you have an RF signal generator ?
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  #30  
Old 05-11-2015, 09:24 AM
dieseljeep dieseljeep is offline
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Originally Posted by maxhifi View Post
I got mine today too! The IF and oscillator coils were hard to tell apart until I realized the oscillator has no cap in the bottom. The audio transformer has a dot on it to indicate which way it installs but it sure isn't obvious. Aside from having the world's worst speaker I am happy with mine.

Yellow wires are for the speaker. The B+ dropping reaistor is marked on the board as 100k, but it really is 100 ohms and is also correct on the schematic. The board has several little solder bridges which have to be closed to allow it to work, presumably for measuring current to assist students to troubleshoot.
The speakers are so shallow, that there's no place for the cone to move.
The novelty radios have the same type speaker and the poor tone proves it.
BTW, can you post the schematic. It seems interesting. Schematics are the universal language.
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