[R-390] Audio

[Bob Camp]

Hi

Excess audio decks used to be a pretty common / cheap item. Swapping around tubes and circuits was an "easy to try" sort of thing. One of the many weak links in the deck (hi-fi wise) is the output transformer. Once you decide to pull it, there's not a lot of use to the deck. 

You'll get better performance simply running a *good* blocking capacitor on the diode load and feeding the audio into a decent high impedance pre-amp input. Use what you have. What ever it is, it'll give you better audio response than the built in audio chain. The radio was designed for limited bandpass communications use. It's great for that purpose. Not quite so great for music...

Bob

On Feb 18, 2013, at 8:54 PM, Robert Newberry <N1XBM at amsat.org> wrote:

> I'm in the process of rebuilding my R-390. I've been doing some reading on
> the net how some people use a resistor and DC blocking cap and feeding the
> diode load into an audio amplifier. I've also heard about a modification
> that is a more permanent mod that involves changing out tubes and
> re-working the audio section. Although I haven't come across that
> information yet.
> 
> I'm looking for input as to what other people are doing.
> 
> Thank you
> Bob/N1XBM
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