Batboard

Here's something I didn't even know existed... it's a multi-channel alert monitor. Although I guess "alert" is a bit of misnomer, since it doesn't appear to have any signaling functions. Just carrier squelch.

The model number is M03CNB-1100A SP23.

It's also the only alert monitor I've seen that has an SO-239 on the back in addition to the usual "RCA" type plug.

None of my manuals or literature reference these options. Has anyone ever seen this before, or have any documentation on it? I'd especially like to know what the function of the "SIMUL/NORM" switch is. It kind of implies that the radio can listen to all 6 channels concurrently? Or some kind of scan?

SO-239 looks added because there is not 2 ribits holding it.
Channel selector knob looks like knob from HT-220.
What is the leaf switch on rear panel?
Never seem this version of receiver.

Is that a metering socket on side of chassis?

My guess is it is some sort of scanning receiver that may be used in a place like a fire station to activate lights and/or horn. The multi-plug on the side near the crystals may be the decoder output to turn on various circuits. The SIMUL/NORM selector probably selects the channels from a scan list (crystals) or if set on NORM it monitors whatever channel the selector is set on. Just a WAG on my part.
Andy
W4KDN

I have serviced hundreds of Alert Monitors but that one is definitely unique.

Looks like it has dual filters sets to allow wider frequency coverage (similar to what was done with the "wideband" MCX100 mobile radios)
The channel select knob looks to be from a HT-220
The metering jack is standard
No alerting board present so this is a monitor only model
The "leaf" switch makes contact with the antenna built into the handle on the case
Would guess that "simul" monitors all frequencies and "norm" selects just one.

PM me with what frequencies you need, I may still have some crystals laying around.

I suspect that the add on board is a whole five freq front end ...the main board channel 1 and front end are enabled with the SIMUL button with 2 -6 being selected for the secondary.

In order to add just five channels you wouldn't need that much HW.

The SIMUL button probably just grounds chan 1 all the time and one of the other channels can also be monitored .

Just a guess based on how they did things back in the day.

That one is unusual for sure and all of those SP units in good shape would demand a lot more value than a typical version ...which i almost zero