[ARC5] eBay C-29/ARC-5 (PB vs. Rotary Selector)

[Mike Morrow]

Robert wrote:

>I have to disagree about the utility (ease or accuracy of use) of
>push-button versus rotary switch selectors.  In a blind test, one
>will find that the likelyhood of pressing the correct button out
>of four in a row is probably much higher than that of one rotating
>a rotary switch to the correct position. 

I wouldn't disagree with that for systems whose switch manipulations
must be made during operator stress.  But...changing channels on a
command radio is NOT an action that would normally be often required
during stressful situations aboard an aircraft.  Everyone should already
be on the appropriate channel.

>I therefore find the four-push button designs as found in
>SCR-522/542/624, AN/ARC-3, 4 ,MAH, MAL and some AN/ARC-5 control
>boxes as being the superior or preferred design.

I believe the pushbutton design was solely an unfortunate legacy
of the original British design upon which the SCR-522 was based.
Its BC-602 is two or three times larger, heavier, and an order
of magnitude more mechanically complex (and costly) than a simple
rotary selector in a box would have been.  The same assessment
applies to the C-118A/ARC-3 vs. C-404A/A, and C-30 vs. C-30A/ARC-5.
The C-45/ARC-1 (for AN/ARC-1 and -12), the C-244/ARC-2, the C-51/ARC-4,
the C-740/ART-13 and C-733/ARR-15, in fact ALL post-WWII controls 
dropped pushbutton designs in favor of a selector switch.  About
the only place it survived was on the RT-246/VRC ground VHF-FM set
in the AN/VRC-12 series.

One additional operating advantage that the C-30A has over the
C-30 is that the channel of the VHF receiver can be changed even
though a MF/HF transmitter is selected, since the VHF channel
selector switch still works even when the VHF transmitter is not
selected.

>Rotary switches are OK if no one is shooting at you and you have
>time to look at them (and can see them).

But no one plays with his radios in combat, especially in WWII when
frequency options were limited.

My Vietnam Army helicopter friends tell me they seldom had frequency
changes on a mission.  Army UH-1D/H models carried an amazing amount of
radio gear (AN/APX-72 IFF, AN/ARN-82 VOR, AN/ARN-83 ADF, AN/ARC-51BX UHF-AM,
AN/ARC-131 VHF-FM, AN/ARC-134 VHF-AM, and sometimes AN/ARC-102 HF SSB).
One told me the biggest radio operation problem he ever had was when
he was flying into a contested LZ, his new guy pilot killed the audio
to the intercom from the AN/ARC-131 tactical FM set while leaving AFRTS
blaring from the AN/ARN-83 ADF.  He still remembers the song being played
by AFRTS as "Light My Fire" by the Doors.  :-)  That was an era when
only the AN/ARC-51BX had selectable pre-set channels.  The -131 and -134
had to have the full frequency dialed on a mechanical digital display using
three or four separate knobs for any frequency change!  That's way beyond
the selector vs. pushbutton issue.

We both agree that pushbuttons are more ergonomic, but I believe that the
likelihood of operating such equipment to change channels under stress is
small.

Mike / KK5F