[ARC5] R-10 in the receivers - Now a Rabbit Hole :-(

[Mike Morrow]

> Be very careful about accepting explanations in military technical
> manuals.

Gosh...what a rabbit hole just developed from a simple technical design
issue explanation!!! But thanks for the warning! :-)

> During war conditions, able-bodied and intelligent people were occupied
> in designing, making and using this stuff. Very few had time to write
> explanations.

Really? Remember...Quod gratis asseritur, gratis negatur! 

Evidence for such would surface clearly were the explanations found in
a manual incorrect or bizarre on even rare occasion. But we have this
specific and simple case to examine. I challenge any knowledgeable reader
to find fault in the cited manual's description of the function of R-10.
It does not cite a requirement of complex number mathematics for
understanding, and it applies simple Ohm's Law to generate key portions
of its conclusion. This old electrical engineer likes its clarity! :-)

It may be of interest, FWIW, that the same explanation, lacking only one
clarifying sentence, appears in the original pre-war (in US) ATA/ARA manual
produced under contract of 29 June 1940. The full explanation is found
in the original pre-war 1941 contract SCR-274-N manual. My money says it
would be found in the manual for the 1938 A.R.C. Type K receivers, if only
such a manual could be found today. (Pardon my own gratuitous assertion!)

> I have found many explanations that read well, but in terms of demonstrating
> electronics knowledge, were pure, arrant nonsense. This explanation falls 
> very near that category. The problem is that a small part of it is probably
> correct - and then the well-known psychological principle of the 'halo effect'
> takes over.

Would you care to trouble yourself with some specific observations from the
manual's explanation of R-10 function?

This allegation against the manual's description is itself pure gratuitous
nonsense, front to back.

> Also, use of carbon pots in place of the original wire-wound pots will
> result in noise that the 3 uF capacitor will not remove.

What "original wire-wound pots"??? Receiver gain potentiometers used in the
ARA/ATA, SCR-274-N, and AN/ARC-5 are Allen-Bradley Type J carbon composition
pots.

Wire wound pots are not used in ARA, SCR-274-N, or AN/ARC-5 receiver gain
circuits. Why bring components not used into the discussion?

>From my 50 years of collecting and studying US military radio equipment manuals,
I find the instances of erroneous technical explanations to be vanishingly small
in number. Where fault exists, it arises from some lack of detail and not from
technical error. 

Study shows that technical explanations found in US manuals...even wartime manuals
...are correct. (I make no similar claims for AWA or UK work.) We should be able to
accept these without the baseless creation of some dark "conspiracy of incompetency"
in their genesis.

Mike / KK5F
(Not a PhD.)