[Boatanchors] Headphone Impedance Matching

[Howard Holden]

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 taking care of 
them."
Thomas Jefferson


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