When I worked at Hughes Aircraft in the 80s and 90s building microwave transmitters and receivers for use in radar cross section imaging I used hundreds of Avantek amplifiers from VHF through 90GHz. Certain models are good for receiver front ends, others for receiver and transmitter IFs, some for transmitter PA drivers and some for transmitter PAs.
The UTC 21-104 might be used in transmitter or receiver IF or for general lab use raising weak signals so they can be measured on test equipment. It could have been used as a broad band receiver front end where you have control over what the receiver sees, like inside an anechoic chamber where it would not get overloaded by off air signals.
An amplifier for feeding a VHF/UHF scanner or receiver should have a low noise figure and a 1dB compression point and IP3 spec high enough so it doesn't get overloaded and create IMD from being hit with strong TV, FM broadcast and cell phone tower stuff. In my area its a big problem and most preamps fail miserably. If your area is not too bad with strong signals you might get by with a Minicircuits ZX60-P103LN. The only thing I don't like about that amp, besides not working well here is its gain slope where its got about 22dB gain in the VHF range, 18dB gain in the UHF range and about 14dB gain in the 800MHz range. That slope should be opposite to make up for higher feedline losses at higher frequencies.
For me the Minicircuits ZHL-1010 is working well but its got a trade off of higher noise figure for higher overload characteristics. Its also got about 10dB of gain which is what I needed and if you are feeding something like an 8-way divider there is a 20dB gain version. Whatever you use you want to attenuate the output of the amp so your overall gain is small like 0 to maybe 4dB. If the amplifier gain is too high its going to reach a problem area with overload sooner than a similar amp with less gain.
Well that's a bummer! What sort of applications would they have been used in back in those days?
I think I've seen you (or perhaps Ubb?) recommend different amps, whats your favorite family or model of amps for something like feeding a distro block?
