[ARC5] More on the "No HF" Myth

[David Stinson]

gordon white wrote:
> From my research into WWII work on various communications problems
> indicate to me that the SCR-274N got a lot of use; 
> that tuning drift was
> the greatest problem, and that it was more or less dealt with.

Thank you for writing, Gordon.  

While the drift problem was certainly real, a lot of 
improvement took place between the GF/RU, SCR-183 sets and
the ATA/ARA SCR-274N sets.  At least some of the "drift"
problem can actually be attributed to operator error.

Anyone who knows pilots, knows that they are a skeptical lot- 
at least, the ones that live very long.  
Pilots tend to carry their notions about systems
over when a new system is introduced.  "Radios drift a lot"
was a preconception applied to any new non-crystal radio.
While an ARA did drift some, it was no where near as 
bad as, say an early RU or a BC-229.
Sometimes a pilot would make a radio call. 
If not answered immediately- he'd cuss the "drifting radio"
and start cranking away on the "coffee grinder," looking 
for an answer from someone in the flight.  Those who hadn't 
dinked with the settings would answer him, get no response
(because his receiver was off frequency), and start
cranking away in their turn.  The next thing you knew you 
had a whole flight with perfectly good comm gear giving 
hand signals to each other and filing reports about
"damn drifty radios."

Very soon after AN/ARC-5 came on line as an "improved" ATA/ARA,
they were retrofitted with further modifications to 
relieve this problem.  On most AN/ARC-5 receivers, you'll 
find a circle with "S" stamped in it.  This indicated the 
receiver had been modified to improve its frequency stability.
The little tuning keys some lucky folks find on the inside of 
the top cover were used to tune the receiver to a fixed 
frequency, then screwed over the tuning gear to cover the hole.
The "coffee grinder" pilot's control boxes were replaced
with boxes like the C-38, which had only switching and 
volume controls.  
That's why you don't see many 3-grinder Navy boxes around.
This "locked tune" solution seems to have worked very well,
because the Navy keep AN/ARC-5 HF in service for a long time
after WWII.

The Army kept the grinders all the way to the end.
I don't have any info on how they kept people from cranking,
but I'd bet they did it the same way they did every thing-
training and YELLING. "Keep your paws OFF, knucklehead!"  ;-)

73 Dave S.

P.S. I pulled out an RE-2 HF antenna relay.  It was overhauled
in 1957 and is tagged pulled from a Navy aircraft in 1959.