[Heathkit] HW-8 Audio Output

[Mark K3MSB]

 This may be a repeat, but I got a "message content not explicitly allowed"
when I sent the first email with an embedded picture....  Sorry if it's a
repeat.

Hi Jeramy and others...

Got the new audio board installed.... easy build.... and fun!

When going from mono to stereo,  I see there are two ways of doing it.  One
way is just to directly connect the L/R channels together at the new stereo
jack.

The other way is to connect a 220 ohm resistor to each stereo channel,  tie
the other end of the resistors together and connect to the mono source.

Any particular benefits or concerns with either?

73 Mark K3MSB



On Mon, Apr 21, 2025 at 9:26 PM Jeramy Thibodeaux <kg4azt at earthlink.net>
wrote:

> This should work!
>
> https://kc9on.com/product/hw-8-lm386-audio-board/
>
> Several people on the heathkit groups.io reflector have endorsed this to
> fix the low impedance speaker issue.
>
>
> 73
> JT
> KG4AZT
>
> On 4/21/25 5:53 PM, Mark K3MSB wrote:
> > Thanks everyone;  I admit to being lazy Ken and I didn't look it up but I
> > figured it couldn't be much.
> >
> > I'm repairing one for a friend and told him he could not use an 8 ohm
> > headset, so I was looking for a matching transformer or line transformer.
> > Lots out there to choose from.
> >
> > I think the Radio Shack 273-1380 should work.
> >
> > 73 Mark K3MSB
> >
> > On Mon, Apr 21, 2025 at 5:26 PM Ken Gordon <kgordon2006 at frontier.com>
> wrote:
> >
> >> On 21 Apr 2025 at 15:38, Mark K3MSB wrote:
> >>
> >>> Does anyone know what the output is rated in Watts?
> >>>
> >>> 73 Mark K3MSB
> >> Well, Mark, according to the manual, the audio output transistor is an
> >> MPS-A20.
> >>
> >> Specs say that maximum collector current is 100 mA at 4 VDC, which
> >> works out to 0,4 watts.
> >>
> >> Does that sound about right to you?
> >>
> >> BTW, if you have not yet found a copy of "The Heathkit HW-8 Handbook 2
> >> ed 2008 " in PDF format, you may find that book to be of interest.
> >>
> >> Ken W7EKB
> >>
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