Found this junk shopping. Locally made with F-type connections for composite and line level mono in and is apparently factory set to "Channel D"

https://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/CGS_9350.jpg
https://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/CGS_9351.jpg

There's sharpie on the side somehow relating D to the number 17, which according to this - When ordering please specify what Channel(s) you would like. We will check availability and advise by email.

AVAILABLE CHANNELS:

VM5: 1 7 8 9 10 11 13 16 17 18 19 21 23 24 25 29 34 36

Requires a 12 VDC power adapter - NOT included.
https://www.torontosurplus.com/a-v-photo-computer/audio-visual-equipment-accessories/nexus-vm-5-television-modulator-see-description.html

...implies this is a UHF RF modulator, but I can't find any more information on it. Is this a rebrand UHF modulator or something less interesting?

http://eaglecomtronics.com/Cable_Television_Channel_-_Frequency_Chart.pdf

Analog cable channel D, also called channel 17; 138-144 MHz, not broadcast channel 17.

It took me a little while to find something to adapt the coaxial connectors to something else but yes, it IS a CATV modulator!
I put a test pattern on the input and tried a Jerrold cable box and the test pattern came in clean and strong on channel 17. :thmbsp:

Hi to all,

Hi MIPS, it's a nice unit and i think it's up to Broadcast quality with Vestigial sideband filtering not dual sideband like consumer units.
I purchased a new one circa 1990, it was on a VHF Band III channel, CCIR (Euro) channel norm. Used with an Avantek wideband power amplifier "brick", it made a decent low power 1 watt TV transmitter to use with your TVs around the house.

I would have loved a Blonder-Tongue modulator, the one with +95dBm output that you can find cheaply today as reformed cable equipment but BT only made Euro models on special order and they cost around 2K$ in 1990.

Best regards
jhalphen
Paris/France