[Boatanchors] Headphone Impedance Matching

[K5MYJ]

I just looked at the schematic for the 75S1. It is designed for HI-Z 
headphones!

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Howard Holden" <holden7471 at msn.com>
To: <dhallam at knology.net>; <Boatanchors at mailman.qth.net>
Sent: Wednesday, December 04, 2013 10:08 AM
Subject: Re: [Boatanchors] Headphone Impedance Matching


> They will probably work but volume will be low. The 600 ohm transformer 
> will help decidedly until you can find a better transformer. You can also 
> try using a 120V to 6V filament transformer. I've done that with an 8 ohm 
> speaker on an early HRO and it works fine.
>
> Not sure how the headphone jack is set up on the 73S3, but if there's a 
> series limiting resistor in there it may make things a little tougher. If 
> there's one there you could temporarily jumper around it, but then don't 
> plug in a regular 8 ohm set until you remove it.
>
> Howie WB2AWQ
>
>
>
> -----Original Message----- 
> From: David C. Hallam
> Sent: Wednesday, December 04, 2013 9:33 AM
> To: Boatanchors at mailman.qth.net
> Subject: [Boatanchors] Headphone Impedance Matching
>
> I picked up a Lincoln headset/boom mike set a few days ago.  The box is
> marked Telex but there is a Lincoln sticker and part number on one end
> of the box.  I found this set listed in a 1968 Allied Radio catalog with
> the specs.  The microphone is a high impedance ceramic element and the
> headphones are 2000 ohm impedance.  The high impedance microphone is OK,
> but what would be the best way to match the 2000 ohm to my 75S-3, or do
> I even have to worry about it?  I have some 8 to 600 ohm matching
> transformers, but nothing to match to 2000 ohm.
>
> David
> KW4DH
>
> -- 
> "I predict future happiness for Americans if they can prevent the 
> government from wasting the labors of the people under the pretense of 
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