I have to look at the schematics but it seems to me the S-40 has an electrodynamic speaker, at least in early versions but the S-40A has a PM speaker with a 1K resistor in place of the field coil. The S-20R has a field coil speaker. Field coil speakers? were very common until after WW-2.? Good magnets were expensive plus the field coil served as a filter choke.
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-------- Original message --------
From: don Root <drootofallevil@...>
Date: 1/11/23 2:22 PM (GMT-08:00)
Subject: Re: [HallicraftersRadios] S-40B - What is the socket on the back for?
Hello Craig and group
While scouring the www for info I ran across this link re the ?S-40A and B
It seems that much of it is from Riders.
who knows what run[s] it represents.
Again I don¡¯t know what to believe ¡ for the 40B,? the writing says it has PM speaker, but the schematic shows an electro-dynamic? .. did it maybe change in mid-run?
?
Plug for S-meter ?and DC power is shown in the S-40A , but not the B , as most people believe to be true.
The last page partly applies to the Halli S-40's ¡ if you are working on one, you may want to read it.?
73 don VA3DRL
