[Boatanchors] Speech Amp Again

[Bob Macklin]

I hope the chassis of the two units are tied together with a substantial
bonding strap and the shield is not use to provide the ground between the
two units!

Bob Macklin
K5MYJ
Kent (Seattle), Wa,
"Real Radios Glow in the Dark"

----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "Bob Macklin" <macklinbob at msn.com>; "rbethman" <rbethman at comcast.net>;
"Barrie Smith" <barrie at centric.net>
Cc: <boatanchors at mailman.qth.net>
Sent: Wednesday, November 19, 2008 12:45 PM
Subject: Re: [Boatanchors] Speech Amp Again


>
> ----- Original Message ----- 
> From: "Bob Macklin" <macklinbob at msn.com>
> To: "Carl" <km1h at jeremy.mv.com>; "rbethman" <rbethman at comcast.net>;
> "Barrie Smith" <barrie at centric.net>
> Cc: <boatanchors at mailman.qth.net>
> Sent: Wednesday, November 19, 2008 2:59 PM
> Subject: Re: [Boatanchors] Speech Amp Again
>
>
> >A shielded twisted pair should have the shield only connected to ground
> >at
> > one end so the shield does not carry current. It is most common to
> > ground
> > the shield at the load end.
> >
> > Bob Macklin
> > K5MYJ
> > Kent (Seattle), Wa,
> > "Real Radios Glow in the Dark"
>
>
> That only holds true on a battle ship where a real ground is established
> (;
>
> In the typical ham shack its a crap shoot if there is any ground and the
> only load is the one the ham has on....hic
>
> That was the reason for my suggesting trying different ends.
>
> Carl
> KM1H
>
> >
> > ----- Original Message ----- 
> > From: "Carl" <km1h at jeremy.mv.com>
> > To: "rbethman" <rbethman at comcast.net>; "Barrie Smith"
> > <barrie at centric.net>
> > Cc: <boatanchors at mailman.qth.net>
> > Sent: Wednesday, November 19, 2008 11:53 AM
> > Subject: Re: [Boatanchors] Speech Amp Again
> >
> >
> >> Shielding may create a ground loop problem between units. If hum is a
> >> problem try the shielding with grounding at one end at a time and
> >> then
> >> both. As John said twisting is the most important step, as it cancels
> >> common mode problems.
> >>
> >> Im using twisted # 16 cloth covered wire (just like in the old days)
> >> to
> >> both of my modulator decks with no hum pickup.
> >>
> >> Carl
> >> KM1H
> >>
> >>
> >> ----- Original Message ----- 
> >> From: "rbethman" <rbethman at comcast.net>
> >> To: "Barrie Smith" <barrie at centric.net>
> >> Cc: <boatanchors at mailman.qth.net>
> >> Sent: Wednesday, November 19, 2008 2:04 PM
> >> Subject: Re: [Boatanchors] Speech Amp Again
> >>
> >>
> >> > Barrie,
> >> >
> >> > I DEFINITELY shield them.
> >> >
> >> > Bob - N0DGN
> >> >
> >> > Barrie Smith wrote:
> >> >> Good Day:
> >> >>
> >> >> Should the leads from the speech amplifier, or the matching
> >> >> transformer, to the input of the HT-4B be shielded?
> >> >>
> >> >> 73, Barrie, W7ALW
> >> >>
> >> >
> >> > -- 
> >> > Bob - NØDGN
> >> >
> >> > _______________________________________________
> >> >
> >>
> >> _______________________________________________
> >>
> >
> >
>
>