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Is anyone familiar with this modulator, the Jerrold C6M aka "Commander 6" model? I got this one as a "free to good home" deal from Don at the 2015 ETF Convention along with some other unsold retired CATV / Satellite items he'd brought to the ETF looking for a buyer and/or new home for them. The only literature I'm able to find through search engines is for the Jerrold C6M II, apparently the next generation of this model with an LED readout in place of the mechanical Channel dials. Hopefully, I can get this working as an addition to a fleet of a few of the more common Blonder-Tongue AM60-550A's that I've picked up on eBay for varying prices. The idea I have is to program the three Blonder-Tongue units for Channels 7, 10, & 13 respectively, set a cheap modulator up with a DVD player on Channel 3, program an ATSC set-top converter box for Channel 4, and set up the Jerrold C6M with its pushbutton channel selector to switch as needed to any of the other channels, simulating medium signal strength OTA reception to achieve the best possible performance on the professional Vintage TV Restoration work done here.
To prevent running afoul of FCC regulations, each source will be limited to no more than about 20mW and one of these little battery portable TV sets will be carried around the property line to make sure that the signal attenuates abruptly beyond the edges of a standard 50'x150' residential lot so there's just enough signal strength to produce a decent picture on receivers anywhere inside the house or out in the garage where final assembly and packaging of large console sets for shipment or customer pickup is done.
Returning to the topic of this Jerrold C6M specifically, none of the internal DIP switches seem to be effective in extinguishing the "REF OFF" LED on the front panel and the only output it seems to produce is an unmodulated carrier corresponding to the selected output channel, no audio or video. I've tested it with antenna "rabbit ears" and with a direct wired connection to the Antenna input of a known working 70's-era 13" Color portable TV, with and without the white coaxial cable "jumper" between its IF OUT & IF IN connections. I've also tried picking off the IF OUT to feed to the IF IN of a known working Blonder-Tongue AM60-550A and reversed the test by sending IF OUT from the same Blonder-Tongue AM60-550A to the IF IN of this Jerrold C6M. Is anyone familiar enough with these to provide some insight into what I might be "missing" here? Operator error, circuit fault(s) in the unit, maybe both? Does anyone have a manual for it? The one for the C6M II is *totally* different.
Here are some photos of the unit (front, rear, & the DIP switches and Settings chart inside the sliding top cover) and the little AM/FM/TV receiver that I use along with a handheld field strength meter to verify compliance with FCC range limits.
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