[Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII

[Mike Everette]

Jason,

Did you actually mean to type "23AU7A" or was it 12AU7A?  If you actually have a 23AU7A in the V13 socket, it's being fed only about half heater voltage.  12= 12 volt filament; 23=23 volts (some weird series string TV tube??).

Better get used to working on high voltage.  If you are scared of it, you really don't have much business sticking your hands in there.... Learn how to do it safely.

Isolate your signal source from the high voltage, using a capacitor.  A 0.01 uF cap usually works well.  Be sure it's rated for at theast the value of the B plus voltage.

73

Mike
W4DSE


--- On Tue, 11/15/11, Jason Hissong <jhissong at gmail.com> wrote:

> From: Jason Hissong <jhissong at gmail.com>
> Subject: Re: [Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII
> To: hallicrafters at mailman.qth.net
> Date: Tuesday, November 15, 2011, 12:41 AM
> Quick update on my SX101 Mk *2* :)
> 
> I worked with a local ham over the radio and he assisted me
> in 
> troubleshooting the radio.  This is what I know:
> 
> I plugged a pair of headphones in and tested the audio
> stage.  I plugged 
> a phono cord into the back, switched the rig to "phono" and
> touched the 
> tip of the phono plug to cause a hum.  I heard the hum
> and the volume 
> control works.  However, when I turn the calibrator
> on, and put the rig 
> to USB or LSB, and tune around, I don't hear the calibrator
> at all.  I 
> did not have an antenna plugged in.
> 
> I tested the 1st Conversion Oscillator (V13, 23AU7A) by
> setting my TS450 
> to 7100kc + 1650kc = 8750kc, made a make-shift "antenna"
> with a test 
> lead wrapped it around V3.  I turned the VFO knob up
> and down the dial 
> and I heard the signal.  I tried this on 80, 20, and
> 15 and heard it 
> there too (changing the TS450 frequency to the appropriate
> frequency).  
> I did not hear one on 10M (I did not try it with 160M).
> 
> I also tried testing the 2nd conversion oscillator (V12,
> 12AT7) by 
> setting my Kenwood to 1600kc, set it to LSB, and wrapped
> the lead around 
> V12.  I did not hear anything.  I tried it with
> 1700kc and set the SX101 
> to USB.  Nothing.  I also tried it reversed in
> case I messed it up.
> 
> So this is where I am now.  The ham who was helping me
> suggested I need 
> to inject a signal to the grid of each stage of the radio
> and hear which 
> one does not work, starting from the audio stage all the
> way to the 
> antenna.  I don't have a signal injector to do this.
> 
> The other thing is, I am used to working on low voltage
> stuff.  I don't 
> want to be putting this signal injector onto the wrong
> thing and *poof*!!!
> 
> 73, Jason N8XE (new boatachorologist)
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