[ARC5] RU, GF, and What Else?

[Kenneth G. Gordon]

On 11 Nov 2015 at 11:35, gordon white wrote:

> The TRF receivers, pre-Type K, were pretty sensitive, I think, though 
> broad.

TRF receivers can be fairly broad, especially at HF, and the higher in 
frequency, the broader. The reason being that all the selectivity must take 
place at the frequency one is tuned to.

The RAK, for instance, a VLF receiver, exhibits single-signal (there is only 
one "side" of zero-beat) selectivity, but its RF coils show very high "Q". The 
RAL, its HF version, does not show single-signal selectivity at HF. It can't.

I would think that the RU would purposely show wide selectivity, since some 
of the aircraft transmitters were no particularly stable or accurately tuned.

Sensitivity in TRF receivers can be quite good, since usually (but not always) 
there will be more than one RF amp ahead of the detector.

> Has anyone done comparisons between the types?

Not I, but I would love to see that.

Ken W7EKB