[Heathkit] SB-644 problem

[Bill Kuhn]

Thanks for responding!

I think the jumper is required regardless (I may be wrong).

In my sb-644 Assembly manual, in the instructions for assembling the
plug, it has you jump between pins 2 and 5 and then connect the brown
wire to that jumper (not to pin 3 which the schematic shows). In the
assembly manual, there is no connection to pin 3 at all.

The VFO as I have been using it (I bought it used a few months ago) was
set up according to the assembly manual (no connection to pin 3, and the
brown wire connected to the jump between 2 and 5). It works as I
described.

Taking a chance, I've changed the plug wiring to what the schematic on
the website shows - the brown wire is on pin 4, and pins 2 and 5 are
jumped. No change in operation but I do now get 12v at test point C when
the remote is set for RX. I think I'm getting closer.

I'm starting to wonder if either Q6 or Q7 is bad (I haven't pulled them
to test yet).

73 DE NO0OO

-----Original Message-----
From: ma.locksmith at juno.com [mailto:ma.locksmith at juno.com] 
Sent: Saturday, November 14, 2009 2:24 PM
To: Bill Kuhn
Subject: [SPAM] Re: [Heathkit] SB-644 problem

As I look at the schematic for the accessory socket on the SB-104, it
looks like there is a jumper between pins 2 and 5....  5 being the relay
coil.  This jumper is shown with arrow points on the lines which I think
means that it's sometimes used and other times not.

My best guess is that in order to use the VFO, you have to cut the
jumper???? in the 104 and use the VFO to complete the connection.

Ed
K1ZOK


On Sat, 14 Nov 2009 12:42:51 -0600 "Bill Kuhn" <BKuhn at kuhngroup.com>
writes:
> I've got an SB-644 VFO hooked to my SB-104A.
> 
> The SB-644 works properly if I have it set for Remote T/R (transmit 
> and receive). The remote freq displays on the SB-104 and I can TX/RX 
> fine on the remote freq.
> 
> If I have it set for Remote RX (where it *should* be using the radio 
> VFO for TX and remote for RX), the radio displays the remote freq on 
> TX and RX and the TX and RX are in fact on the remote freq.
> 
> If I have it set for Remote TX (where it *should* be using the radio 
> VFO for RX and remote for TX), the radio displays the Radio VFO freq 
> and TX and RX are on that freq.
> 
> Basically, split operation is not working. I'm either all on the 
> remote or all on the radio.
> 
> Checking test points, I'm supposed to be getting 13V on test points 
> A, C, or D depending on whether I'm switched for Remote RX or Remote 
> TX. I get 0V no matter what on these test points.
> 
> Looking back a bit for a voltage source, I see I should be getting 
> 13V in on a line coming in from the radio. This (brown) wire is 
> confusing. 
> 
> >From the assembly instructions, It is supposed to connect to pins 2 
> and 5 of the accessory jack on the radio.
> 
> >From the schematic I downloaded at 
>
http://www.vintage-radio.info/download/download.php?dir=heathkit&file=sb
-
644.zip, 
> it shows a plug wiring diagram with the brown wire connecting to pin 
> 3 of the accessory jack, which is 13V switched on tx from the radio 
> (best I can tell).
> 
> The schematic I have in my sb-644 assembly manual does not show the 
> plug wiring at all.
> 
> Anyone know which is correct?
> 
> If I'm making stupid assumptions or otherwise doing something 
> stupid, please be kind :)
> 
> __________________________________________________
>  
> Bill Kuhn - MCSE , Microsoft Small Business Specialist
> President
> The Kuhn Group, Inc.
> A Microsoft Certified Partner
> 
>     E-Mail:  bkuhn at kuhngroup.com
>        Web:  http://www.kuhngroup.com
> Toll Free: 877-367-5846
>      Office: 785-437-3277
>   Callsign: NO0OO
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