Transoceanic 3000-1
 

I brought home a Zenith TO 3000-1 last weekend. FM works fine, but none of the other bands work. I have cleaned the band switch but that didn't help. The voltages with the AM mixer transistor installed drops to 0 at the collector. With the transistor out the voltage is over 7 volts. I pulled the ground lead back and reinserted the transistor and the voltages were still low, but closer to normal. I have tried different transistors, but I don't have any original replacements. Any ideas? Anyone have any replacements for zenith 121-351, 121-350, or 121-44. Like I said FM works fine and the radio sounds really good.

Zenith prescribed the following for the transistors in your radio:

Source is Zenith Transistor spec guide 902-656, dated Feb 1970.

Royal 3000:

121-44 2N370
121-228 2N1742
121-46 2N109
121-47 2N270
121-48 2N371
121-49 2N372
121-64 2N405
121-230 2N1745
121-137 2N1180
121-138 2N1180
121-139 2N1180

It doesn't show the 121-350 or 121-351.

Zenith makes a point - "Due to wide characteristics within any given EIA or manufacturer's number, performance may not be identical to Genuine Zenith Transistors."

Zenith almost certainly consolidated the older part numbers into newer part numbers. I have a series of Zenith Parts Listings with Zenith specified replacements on microfiche, but my microfiche reader has a bad bulb, else I could help there. NTE replacements would almost certainly work, but they get pricey....

Cheers,

I did a part number cross:

121-44 ECG126, NTE 126, HEP638 $5-$17, Google shows
121-350 ECG160, NTE 160, HEP 639 $3-$14, Google shows
121-351 ECG160, NTE 160, HEP 639 $3-$14, Google shows

Hope this helps,

Good news! The radio now plays fine on all bands. The mixer transistor 121-351 was tanked and I replaced it with an ECG160. Found the voltages close on the oscillator transistor, but there was a lot of leakage to the shield. I bent the shield pin up and plugged it back in and everything fell into place. It is very sensitive and sounds great. I will eventually recap it, but right now I think a little cleaning and I will call it done. I only paid $29 for it at a flea market in Rogers Arkansas. I'm happy! Thanks for the information guys.

Excellent!