[Hallicrafters] Hallicrafters Digest, Vol 60, Issue 15

[Don VE3HUR]

Thanks Jim,

Guess I'm chasing after something that's "normal".

73, Don

On Fri Jan 16 12:56:58 2009 james.liles at comcast.net (Jim Liles) wrote:
> 
> Good morning Don:
> The resistance chart is incorrect for V19-P1 --- it has a 234K resistor in 
> line.  When using the VOX to control CW break in the first keystroke needs a 
> moment to pick the VOX relay and engage the drivers.  If your first 
> character begins with a dot, you will be disappointed.  Kindest regards Jim 
> K9AXN
> 
> 
> > Message: 1
> > Date: Thu, 15 Jan 2009 14:23:46 -0500 (EST)
> > From: Don VE3HUR <dstalk at execulink.com>
> > Subject: [Hallicrafters] SR-400A VOX problems
> > To: hallicrafters at mailman.qth.net
> > Message-ID: <m1LNXoh-00HXAZC at smp>
> > Content-Type: text/plain; charset=us-ascii
> >
> > The VOX on my SR-400A clips off the first dit of a CW character. It's
> > not a sharp clipping but, rather, a slow dit/dah seems to fade in.
> >
> > The sidetone sounds ok and there is 12V P-P at the junction of R143 and
> > R144 so I presume that the sidetone generator is ok.
> >
> > As per the manual, I measured the resistances around V19 and V20 and all
> > were ok except for V19 pin 1 measuring 242K (should be 130K) and V20
> > pin 2 measuring 3.9M/10.1M (should be 3M/7M).
> >
> > Voltage measurements on V20 were within tolerance. However, on V19 pin 1
> > was only 81 volts (should be 135). Pin 7 was -106 volts (should be -130)
> > but since that is to cut off V19A it should be ok. All voltages are for
> > CW operation. The +230V line is ok and the bias line is -135V.
> >
> > I checked the resistors around V19 and V20 by measuring them in circuit
> > and they all measured within tolerance except for R159 which tested ok
> > when removed from the circuit.
> >
> > For test purposes I've disconnected the anti-trip by disconnecting R157.
> >
> > The two times I operated SSB I was told my audio was ok. I used an
> > old Turner desk microphone and didn't have gain problems.
> >
> > Does anyone have any suggestions about why V19 pin 1's voltage and
> > resistance are so far off. Also - any suggestions about diagnosing the
> > VOX problem?
> >
> > 73, Don VE3HUR
> 
> ______________________________________________________________
>