[Heathkit] [SPAM] Re: [SPAM] Re: SB-644 problem

[Bill Kuhn]

It's obviously too early in the morning for me.

I have the brown wire on pin 3!!

-----Original Message-----
From: heathkit-bounces at mailman.qth.net
[mailto:heathkit-bounces at mailman.qth.net] On Behalf Of Bill Kuhn
Sent: Sunday, November 15, 2009 9:00 AM
To: ma.locksmith at juno.com; Heathkit at mailman.qth.net
Subject: [SPAM] Re: [Heathkit] [SPAM] Re: SB-644 problem

Thanks for your reply!

It was a typo - I have the brown wire on pin 4.

I have an SB-644 (no mention of 'A' on it). I haven't found anything
that tells me what the difference between the 644 and the 644A is yet.

I'm going to redo the switch wiring and see if I can get some Deoxit
into the switches (not sure if I can).

I'll post my results.

73 DE NO0OO.

-----Original Message-----
From: ma.locksmith at juno.com [mailto:ma.locksmith at juno.com] 
Sent: Sunday, November 15, 2009 7:59 AM
To: Bill Kuhn
Subject: [SPAM] Re: [Heathkit] SB-644 problem

First, do you have the SB-644 or a SB-644A?
 
I'd expect the interface wiring to the transceiver would be the same, so
the schematic I have (SB-644A, attached) shows the brown wire on pin
3...
 not 4.  And, the schematic for the 644 that I have shows that same wire
on pin 3.  

When I look at the schematic for the SB-104 transceiver, the accessory
socket has no connection to pin 4, but does to pin 3.  So, something is
wrong with the info you have.

Or, is that a typo in your "Taking a chance" paragraph...?
 
The jumper.....  looks like it's required.....  with nothing connected
to the accessory socket, you need the jumper on the transceiver.  If you
connect the VFO, the jumper is in it.

Now that I see how the switching is done, you may very well have a dirty
switch contact problem.  It appears that they use a series of forward
biased diodes to perform the switching function....  not the switches
themselves.  They only supply the bias voltage to the diodes.
 
Ed
 
On Sat, 14 Nov 2009 14:42:24 -0600 "Bill Kuhn" <BKuhn at kuhngroup.com>
writes:
> 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.
> 
> 
> 73 DE NO0OO
> 
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