Conar (NRI) kit radio

[radiotvnut]

I picked up this little AM radio at the flea market and it had me confused until I opened it. On the tuning knob, it says "transistor". On the back, it says: "This cover is provided with a safety interlock to prevent dangerous electrical shock. Do not attempt to defeat it's purpose. To service tubes, remove cover completely". Opening the radio confirmed that it's a 5 transistor hot chassis design. I also know that CONAR was a kit that was provided through NRI as part of it's radio/TV course. And, the soldering on this set confirms that it was a kit. If I'm reading the date codes correctly, this radio is from 1970. It does play; but, is weak and probably needs those white electrolytic caps replaced. It's obvious that this same radio case also housed a tube radio. Anyone ever seen one of these?

[Sandy G]

Cute widdle feller...

[bigmsound]

Conar and NRI were brand names of electronics kits put out by the N R I (National Radio Institute) correspondence course during the 1950's & 60's. NRI was heavilly advertised in Popular Electronics magazines amongst other publications during that time period. The cabinet used in that kit looks like it
came from an old Zenith tube table radio and the chassis was retrofitted to fit properly. NRI probably purchased a large amount of old Zenith cabinets in bulk and modified them.

[bob91343]

Is there a zener diode to regulate the power? Of course the 150V or so out of the rectifier was way too much for the circuit.

If it's 1970, it's probably silicon transistors and the power is positive voltage. That 10W green resistor is the main dropping resistor for the power. The heat sink for the output stage hides the transistors. But looking at the different styles of IF transformer, it really is a hodge podge of whatever parts they could find.

I have always felt sorry for those gullible fellas who paid good money for those correspondence courses. NRI is very old, National Radio Institute, and they go back before WW II if I remember correctly. (I go back before WW II also!) Wasn't that JE Smith the guy whose pic was in most of the early ads? Then there was Coyne, ICS, and CIRE (Cleveland Institute of Radio and Electronics).

[holmesuser01]

My uncle, who is credited for getting me into radio and TV's gave me a complete set of NRI radio courses from around 1938 or so. J.E.Smith had a "pep talk" page on the back of each course issue.

I read them all, and started fixing old 5 tube radios when I was around 11 years old.

I bought an NRI TV course in 1974 from a friend that blew up the first circuit he built... I think it was the power supply for the oscilloscope... He wired all the capacitors positives to ground, IIRC... After I built everything, I had a little better understanding of how solid state stuff worked. I never used that little scope. It wasn't good for much. It still works, though, as I plug it in and let it run now and then. The 25V color TV I built still exists, too. I took the CRT out of it and put it in an RCA CTC 74 (?) the one with the vertical chassis and all the modules... There's an old Magnavox CRT in the Conar set now. It looks pretty decent for its age.

[ctc17]

Is there a model number on it?

Looks like its only half wave and the resistor. No need for any regulation so long as everything works. The bias on the output acts as a fixed load to keep the voltage around what they want

[Jeffhs]

This radio must have been marketed after 1963, as the tuning dial does not have the Conelrad icons at 640 and 1240 kHz. These markings were required by U.S. Conelrad regulations on all standard broadcast receivers made between 1953-1963.

BTW, the tuning scale on the knob looks terribly crowded. I guess these radios weren't meant for use in urban or near-suburban areas with strong signals -- it looks like local stations would come in one on top of the other in a really strong signal area, or a city such as Chicago, New York, etc. with many 50kW transmitters operating from one location. Seems to me just one strong station would all but hijack the dial, let alone two or more.