[Milsurplus] WTB Headset Parts

[WA5CAB at cs.com]

The nominal impedance of the ANB-H-1 receiver is 300 ohms.  The R-14 is 
4000 ohms.  When connected to an HB-7 or with the interconnecting wiring in 
either the tanker helmet or the aircrew canvas "helmet" or skull-cap, they are 
in series, so either 600 ohms or 8000 ohms.  The nominal output impedance of 
the Signal Corps audio output transformer secondaries of the period was 
either 4000 or 250 ohms.  I once read somewhere that the idea behind this was 
that you could connect from one to four of the correct audio loads to either 
system without exceeding a 2:1 impedance mismatch.  That being said, if all 
that you have is one HS-23, HS-33, LS-3 or LS-9, it will appear to work in 
either system, albeit maybe not as well as the proper one would.  But if you 
have one Lo-Z and one Hi-Z load and plug both of them in, only the Lo-Z one 
will work.  Also, the impedance of the R-30 receivers in the HS-30 ear-plig 
type headsets is 128 ohms each, or 256 ohms when connected in the normal 
way.  So you don't want to mix those with the others, either.  Although they 
would probably work with an HS-33' or an LS-9 or 11 if each had its own volume 
control pot and the source output were turned up enough.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 10/12/2017 12:16:57 PM Central Daylight Time, 
kgordon2006 at frontier.com writes: 
> On 12 Oct 2017 at 9:51, Brooke Clarke wrote:
> 
> >Hi Floyd:
> >
> >Maybe the ANB-H-1 Headphones?
> >http://prc68.com/I/MAA.shtml#Headsets
> 
> The ANB-H1s are excellent headphones, although they are 600 ohm 'phones.
> 
> I think Floyd mentioned R-14s. Those are high-impedance 'phones. I think 
> they are at least 
> 2K ohms.
> 
> I've used both and have found that the R-14s sound so much better in my 
> ears than the 
> ANB-H1s, although both work very well with my gear here.
> 
> Still, I much prefer the R-14s.
> 
> Ken W7EKB
> 
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