[ARC5] SCR-274N side tone level?

[Michael Hanz]

Of course, don't forget that to authentically calculate that output 
voltage, one must take the square root of 6.667 by using Prime 
Factorization method.  No fair using a computer.

Running and dodging,
  - Mike

On 2/9/2019 2:31 PM, Robert Downs via ARC5 wrote:
>
> I had forgotten about that.  If your BC-456 is a BC-456-B or BC-456-E 
> and is strapped for HI-Z audio, changing the two transformer 
> connections to LO-Z will reduce the voice and CW sidetone output 
> voltage by theoretically SQRT(6.667) without having any effect one way 
> or the other on the receiver audio, regardless of what mix of 
> receivers you have.
>
> Robert Downs
>
> *From:*arc5-bounces at mailman.qth.net 
> [mailto:arc5-bounces at mailman.qth.net] *On Behalf Of *Michael Hanz
> *Sent:* Saturday, February 9, 2019 10:49
> *To:* Dave Kirk; arc5 at mailman.qth.net
> *Subject:* Re: [ARC5] SCR-274N side tone level?
>
> Table 8 in the manual says the sidetone voltage on CW is 7-9 volts 
> into 4,000 ohms.  Are you using low impedance earphones?  If you are, 
> you might try an MC-385* headset adapter to lower the volume. Or, you 
> might check to see if you have a low impedance tap on the sidetone 
> transformer, T-50, in your modulator.  Here's the note on the tap:
>
>
>
> Or, you could just put an appropriate resistor in series with the jack 
> to your headphones...:-)
>
>  - Mike  KC4TOS
>
> On 2/9/2019 10:52 AM, Dave Kirk via ARC5 wrote:
>
>     I run a stock SCR-274N setup with a BC-456 modulator not sure if
>     this is normal, but the side tone in CW, and phone is ear piercing
>     I can't even wear my headphones its so loud. Is there a simple way
>     to lower the level? So far I haven't seen in the manual any
>     mention of level adjustment. Guess I understand why its loud the
>     radio dude needed to be able to hear the radio during flight, but
>     dang this is ridiculous.
>
>     Dave
>

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