And here is the RCA KRK-226 UHF tuner of 1975:
It was RCA’s first, and I think the first UHF tuner anywhere to use a dual-gate mosfet RF amplifier, foe which a 10 to 20 dB reduction in cross-modulation was claimed.
There was a preceding UHF varactor tuner that used a grounded base bipolar RF amplifier. The grounded base IF preamplifier in the KRK-226 was a carryover from this previous model, so one may infer that the use of a mosfet in this position was not justified.
The KRK-226 was intended to work with the KRK-228 VHF tuner, also of 1975, with the UHF IF going to the mixer, not the RF amplifier:
This was RCA’s first VHF tuner to use a dual-gate mosfet in the mixer position, for which it claimed a 10 to 20 dB reduction in channel 6 colour beat. RCA wasn’t though the first to use dual-gate mosfets in both the RF amplifier and mixer positions. Others, I think including Zenith and Magnavox, got there first.
The preceding VHF varactor tuner would have used a cascode bipolar mixer. The latter goes back at least to the KRK-142 of 1968. This was a switch tuned unit that was the first anywhere to use a dual-gate mosfet as RF amplifier:
The cascode bipolar mixer may have had earlier use, I’m not sure. As far as I know, preceding the KRK-142 was a top-end VHF tuner that had a nuvistor RF amplifier and a bipolar mixer; the latter may well have been of the cascode type.
The KRK-132 UHF IF input was to the RF amplifier, and it was designed to work with the KRK-132 UHF tuner, which was probably similar to the KRK-120.
Cheers,