Monarch ST-100 Tuner

[SA-300]

This Monarch ST-100 tuner followed me home a while ago after the dual tuning eye tubes caught my eye. I haven't done anything to it and have only used it sporadically but recently I've become curious and want to learn more about it. A few tries at googling it haven't turned up more than a few similar Monarch models. Nothing about the ST-100 as far as I can tell. Can anyone fill in some details? Specific questions I have are below the photos.

FM selected:


AM selected:


Rear panel:


FM antenna terminals, selectable (with a fuse) input voltage, and one output jack:


Output jacks, output selection switch, AM antenna terminals.


Questions that come to mind include:
- Is there a way to date it? I'm guessing early-mid 1960s.
- How common was an AM selectivity knob (3KC, 10KC) on tuners? I've seen them on AM and SW radios before.
- What would the AM-FM selection do? Is that for stereo?
- What's the proper way to wire the FM antenna? Using A1 and S2 seems to work, but what's the 3rd terminal for?
- How do the three outputs on the right side of the output switch work? They're labeled, "FM-M/X FM-S-AM". Are FM-M/X and FM for FM stereo with a decoder of some sort? And are FM and AM for AM stereo?

Thanks for any insight,

/Mark

 

[gadget73]

60-62 most likely. You could open it up to see if there are date codes on anything, but FM stereo in it's current configuration came about in 1962.

AM variable bandwidth mostly existed on these era simulcast units. The idea was high fidelity AM when available, or reasonable selectivity with low noise when that made sense.

Yep, AM-FM simulcast. Related to the above actually. AM was your left channel, FM was the right. The wide bandwidth was to make them sound as similar as possible. They had really kick-ass AM tuners as a result of this. I have a Sherwood and a Fisher receiver from this era with the simulcast setup and if AM had anything worth listening to, they'd do a spectacular job of pulling it in.

Not sure about the antenna, possible its to let you switch from balanced twin lead to unbalanced coax input? Guessing A1, A2 for twin lead, and bring the jumper in for unbalanced.

FM-MX is output to an external stereo demultiplexer. This will let you get modern FM stereo broadcasts. The other two outputs would go to the left and right channels of the preamp for AM-FM simulcast. Some preamps from this era actually were marked FM-AM on the tuner input when run in stereo mode. My Dyna PAS2 is at least.