[ARC5] RU/GF sets

[Kenneth G. Gordon]

I realize that the RU/GF sets were one of those types that were used before 
the "ARC-5" types appeared, but I am curious if anyone here is using or has 
used them in the past, and what was your experience with them.

One reason I ask is that for many years, I used an RAL-7 as my main station 
receiver and came to really appreciate what a really good HF TRF receiver is 
capable of doing.

Since the RU was also an HF TRF, I am wondering how it might compare 
with the RAL.

Were there any other military HF TRF receivers which were used "back 
then"? 

I know that the German's used TRF receivers in their aircraft almost 
exclusively in WWII, and that the Japanese also made heavy use of them, 
but were any other combatants using them then?

Ken Gordon W7EKB