Quote:
Originally Posted by Electronic M
Those screws are probably for an antenna.
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No, I'm afraid not. My own Zenith C845 has those screws as well, and they are marked for an external speaker; they are near the radio-phono selector switch at the rear of the radio, and are in fact marked "External SPK'S input". However, when I connected a speaker to them, I heard nothing.
I read somewhere awhile ago, don't remember where, however, that those "external speaker input" terminals are only active when the radio is used with Zenith's "Stereo Multiplexer", model MH-902, IIRC. This was an add-on (which may show up on eBay every once in a while) for certain models of Zenith radios that would supposedly convert these older sets to stereo FM. The "Multiplexer" had an FM tuner, multiplex decoder circuitry complete with stereo indicator light, and an amplifier and speaker, which could be used by itself as an FM radio -- that is, if you didn't mind listening to just one half of a stereo FM broadcast. However, the Stereo Multiplexer was designed to work with the C-845, and probably others in that series (H- and L-845); the latter would provide the other stereo channel.
The FM antenna connections are marked "F" and "G", and are located on the radio's back cover. "F" stands for FM, and is the terminal to which an external single wire antenna would be connected. "G" is ground. It is normally used only in cases where two-wire feedline is being used from the antenna back to the radio. One of those leads goes to the "F" terminal, the other to G. There is no polarity involved, so the 2-wire antenna can be connected either way; however, when a
single wire is used as an antenna, it must be connected to the "F" terminal. Leave the "G" terminal alone in this case. If the FM antenna is mistakenly connected to the "G" terminal, you will get no reception, as you will be literally grounding out the external wire -- leaving the radio with no antenna. This connection
might work if you have one or more extremely strong FM stations in your area (the radio would actually be picking up the extremely strong signal on its own tuner wiring), but in most cases and in most signal areas an antenna lead connected to "G" will result in no reception at all.
BTW, whatever you do,
don't touch the grounded antenna terminal when the radio is in operation. The 800 series Zeniths, including the C/H/L-845, et al., are AC-DC sets which have one side of the chassis connected to the AC line. Should the AC plug be inserted in the wall socket such that the chassis is hot with the line voltage, contacting the grounded antenna terminal and the chassis simultaneously (or the chassis and a grounded object) could be lethal.
This warning also applies to very old AC-DC radios with external AM antenna connections, and goes
at least double for such radios housed in metal cabinets; the Arvin model 540T comes to mind as I write this, as I had one many years ago. The problem occurs because the insulation material, usually rubber grommets, between the radio chassis and the metal cabinet will deteriorate over time, becoming hard and possibly even conductive. Again, depending entirely on which way the AC plug is inserted in the wall socket, the chassis could be hot with the full line voltage, and any contact with same, say via the external AM antenna terminal, will result in a very possibly lethal electrical shock. Always remember to unplug the set before connecting or disconnecting the external antenna, if one is used.