[Heathkit] SB-610 scope to SB-303 receiver

[Tom Chesek]

I'm jumping in here with a question. If you shunt signal to ground does this
affect the receiver sensitivity?

Tom K3TVC


----- Original Message ----- 
From: "jeremy-ca" <km1h at jeremy.mv.com>
To: "Bob Macklin" <macklinbob at msn.com>; "Dan Pividal"
<dpividal at tampabay.rr.com>; "heathkit at mailman.qth.nt"
<heathkit at mailman.qth.net>
Sent: Tuesday, December 11, 2007 8:12 PM
Subject: Re: [Heathkit] SB-610 scope to SB-303 receiver


> 10:1 of almost nothing is still almost nothing. The issue is how LITTLE of
a
> signal is required to drive the scope and not the amount shunted to
ground.
>
> Carl
> KM1H
>
>
>
>
> ----- Original Message ----- 
> From: "Bob Macklin" <macklinbob at msn.com>
> To: "jeremy-ca" <km1h at jeremy.mv.com>; "Dan Pividal"
> <dpividal at tampabay.rr.com>; "heathkit at mailman.qth.nt"
> <heathkit at mailman.qth.net>
> Sent: Tuesday, December 11, 2007 7:37 PM
> Subject: Re: [Heathkit] SB-610 scope to SB-303 receiver
>
>
> >A 2pf cap connected in series with a 22pf cap produces a 10:1 voltage
> >divide
> > at any frequency!
> >
> > Bob Macklin
> > K5MYJ
> > Seattle, Wa,
> > "Real Radios Glow in the Dark"
> > ----- Original Message ----- 
> > From: "jeremy-ca" <km1h at jeremy.mv.com>
> > To: "Bob Macklin" <macklinbob at msn.com>; "Dan Pividal"
> > <dpividal at tampabay.rr.com>; "heathkit at mailman.qth.nt"
> > <heathkit at mailman.qth.net>
> > Sent: Tuesday, December 11, 2007 4:29 PM
> > Subject: Re: [Heathkit] SB-610 scope to SB-303 receiver
> >
> >
> >> Luckily, 22pf has minimal effect at the frequency of interest.
> >>
> >> Carl
> >> KM1H
> >>
> >>
> >> ----- Original Message ----- 
> >> From: "Bob Macklin" <macklinbob at msn.com>
> >> To: "jeremy-ca" <km1h at jeremy.mv.com>; "Dan Pividal"
> >> <dpividal at tampabay.rr.com>; "heathkit at mailman.qth.nt"
> >> <heathkit at mailman.qth.net>
> >> Sent: Tuesday, December 11, 2007 5:37 PM
> >> Subject: Re: [Heathkit] SB-610 scope to SB-303 receiver
> >>
> >>
> >> > Remember that coax like RG-174 is about 22pf/ft. The coupling cap and
> > the
> >> > capacitance of the coax will be a voltage divider.
> >> >
> >> > You want to use the smallest possible coupling cap to reduce the
> >> > loading
> >> > on
> >> > the IF stage. I would recommend using a GIMMICK.
> >> >
> >> > Bob Macklin
> >> > K5MYJ
> >> > Seattle, Wa,
> >> > "Real Radios Glow in the Dark"
> >> > ----- Original Message ----- 
> >> > From: "jeremy-ca" <km1h at jeremy.mv.com>
> >> > To: "Dan Pividal" <dpividal at tampabay.rr.com>;
"heathkit at mailman.qth.nt"
> >> > <heathkit at mailman.qth.net>
> >> > Sent: Tuesday, December 11, 2007 1:35 PM
> >> > Subject: Re: [Heathkit] SB-610 scope to SB-303 receiver
> >> >
> >> >
> >> >> Well at first you said bypass and now you say coupling; there is a
> >> >> huge
> >> >> difference.
> >> >>
> >> >>  Mmf is now pf;  mf is still mf.
> >> >>
> >> >> Either the manual has a typo or you need glasses or maybe both <G>
> >> >>
> >> >> A very low value of 1-12pf is more like it and you select a value
that
> >> >> doesnt overdrive the scope. Use a trimmer if you have one and then
> >> >> measure
> >> >> the value that gives the best results and replace with a fixed
value.
> >> >>
> >> >> For such a short run any miniature coax is OK, RG-174, 178 and 179
are
> >> >> common ones.
> >> >>
> >> >> Carl
> >> >> KM1H
> >> >>
> >> >> ----- Original Message ----- 
> >> >> From: "Dan Pividal" <dpividal at tampabay.rr.com>
> >> >> To: "heathkit at mailman.qth.nt" <heathkit at mailman.qth.net>
> >> >> Sent: Tuesday, December 11, 2007 3:46 PM
> >> >> Subject: [Heathkit] SB-610 scope to SB-303 receiver
> >> >>
> >> >>
> >> >> >I am trying real hard to hook up an SB-610 to an
> >> >> > SB-303.
> >> >> > If anyone has done the mod to monitor the receive envelope please
> >> >> > let
> >> >> > me
> >> >> > know what value of coupling capacitor you used with success.
> >> >> > Seems the Heathkit SB-610 assembly manual says to use a 1.0mmf
> >> >> > Also says, they supplied the 1.0mmf as well as a 2.2mmf and a
12mmf
> >> >> > capacitor in the original kit.
> >> >> > I believe that long ago mmf meant Picofared.
> >> >> > That would make a big difference.
> >> >> > Tech notes I have from Heathkit says to use a 1.0mf coupling cap
to
> > the
> >> >> > 3rd IF via a RG174 coax to a spare RCA plug in the back of the
> >> >> > receiver.
> >> >> > To which document do I pay heed.
> >> >> > Thanks in advance for any help in clearing this up.
> >> >> > Dan/N4VET
> >> >> >
> >> >>
> >> >>
> >> >
> >> >
> >>
> >>
> >
> >
>
>
>
>
> -- 
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