Alan,
When the Scout first came out, hams were using Communications Headphones.
These were of two types: Ex aviation or military 600 ohm sets, or high
impedance- both military like my HS 34, (higher impedance to thousands of
ohms when you include the crystal headphone, (piezo) elements), and the
Trimm models of 1000 to 2000 ohm impedance, (single or double headphones
respectively.) Any 600 or higher impedance phone is a good match to the 600
ohm connection. (IE does not load down the audio circuit), and 600 ohms is
an audio standard. (Ten Tec after all, derived from Electro Voice, a
microphone and Audio products company).
600 ohms as a line impedance audio output standard was Broadcast and
military standard for many years. In later times, Japanese consumer audio
products included the 1500 ohm line outputs for audio, to use transistors
without need for a transformer.
The 8 ohm or 4 ohm headsets or even the 32 ohm stereo sets are really not
the best to use for communications, (ham) bands. You want to restrict the
frequency response to voice or CW band, and not have to listen to the hum or
higher frequencies that might be on the audio from automotive noise,
ionospheric noise, etc.
The simplest solution if one does not buy a new 2000 ohm headphones from
Antique Electronic Supply, is to either find the military or old civilian
phones, or install the 600 ohm to low impedance transformer stocked for many
years by Radio Shack to use low impedance phones.
Best of all is the 34 model mil set I got NOS. They are magnetic phones,
favoring voice band. The impedance loads the Scout so little I hardly have
to turn up the audio. These were Korean war vintage, so might be available
from surplus outlets like Fair Radio.
I solved the headphones cushion need on them, by using two round disks of
soft foam sold at Walgreens for refills for ladies face powder compacts. I
think the pair were less than a dollar, and are a pleasent off white. You
cut two round holes in the middle of each to line up with the hole in the
headphones. Place double sided Scotch tape on the foam and apply the foam
piece to the headphone earpiece. (These are the large phones that sit
outside the ear, made of hard black plastic material or bakelite).
Put the phones on and enjoy good comfort, as good as my $125 Hi Fi cushioned
phones. My total investment, perhaps $16, 15 of which was for the surplus
phones from a local, new in the sealed package with 1953 date on it.
73, Stuart K5KVH
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