Yes
The 1st UHF transistor (BFG67) could be replaced with a BFG520.
It might lower noise figure a couple of tenths of a dB.
Prrobably need to retune.
The transistor substitution works fine, did that when replacing balun.
Based on the circuit design, the components, and comparative testing:
The older 0064/0264 have about the same noise figure as the BT Galaxy series.
Image of CM0064 with half-wave balun below:
The coax is RG-180 (95 Ohm). The impedance is not ideal, but in some ways better than 75 Ohm coax.
It could be better if the impedance for the loop was 150 Ohms.
But, such cable would have to be custom made and it would probably be too large to fit in the case.
The noise that is bothersome in preamplifiers is usually in the same frequency range as the desired signals (MHz).
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