Line-cord antenna coupler - safe on new cord?; tube substitutions

[Jeffhs]

Originally Posted by radiotvnut

I just looked on the internet and the 117Z3 is a rectifier tube only. IIRC, I have seen this tube used in some 3-way portable radios. The 117Z3 was only used when the set was run on AC power. I did find a 70L7 tube on the internet that is a combination rectifier and audio output. I can visualize this being used in a phonograph. Those little one tube amplifiers are not very powerful. The amplifier tube does not have enough gain when used with low output cartridges. That's why they used high output crystal cartridges. These crystal cartridges are almost always bad and there is a good chance that even a NOS one is not any good.

I have a Califone 1410 tube record player made in 1970 that has a transformerless chassis. The tubes are 50L6 and 12AV6 and the rectifier is a silicon diode. I had a Newcomb once that was transformerless. It used two 50L6's in push-pull and a 12AV6. The rectifier was also a silicon diode. The rest that I have seen all had power transformers. Was that Califone you had one of those big monsters with the speaker in the lid? I've got a Newcomb like that and it has some power to it.

Thanks for the information on the 117Z3. I should have known it was just a rectifier since the tube only has three elements, including the filament. The 70L7, however, is a new one on me, even after 40-some years of electronics experimenting.

My Newcomb phonograph had its front-facing speaker mounted in the cabinet; nothing in the top cover that I can remember--in fact, I don't think I ever had a cover with it since I got it. I do remember Newcomb phonos with huge external speakers; we had a few in the elementary school I attended as a kid in the '60s. Nevertheless, my own Newcomb phono had a very powerful amplifier. Wouldn't have wanted to run it wide open in the summer with the windows open (I still lived in a house at that time [early 1970s]; I'd really have a mess on my hands, however, if I ever played anything that loud in the apartment in which I live today). The neighbors probably could have heard it for blocks around at full volume.