Heathkit DX-60 "key down" with no key in!

[K8AXW]

REQ:  I can still remember to put the iron down.  I don't recall EVER haywiring anything in 45 years of building!

[KE3WD]

REQ:  I can still remember to put the iron down.  I don't recall EVER haywiring anything in 45 years of building!

Neither can I, but that's more likely due to a rather selective and somewhat failing memory, right? 

73

[K8AXW]

WD:  The first thing I built more than 50 years ago (not a kit) was "haywired."  It worked perfectly.  So I tore it down and wired it "right" and it never worked after that.

So I developed a philosophy after that of wiring something "right" the first time and making it work.  Never deviated from that, ever!

[K9MHZ]

Hey guys,

Veering off a little, but DO THIS.................

Take the two red HV wires off of your function switch and put them on the normally open lugs of a good relay.  Where the red HV wires used to be on the function switch, run some low voltage AC (or whatever you can steal from an adjacent component....I think I tapped some filament AC from the speech amp tube) to be switched with the function switch, and then to the coil of the relay.  That will take away the HV sparking from your function switch.  The HV inrush into the big elect. caps produce a terrible spark that pits and corrodes your function switch contacts, which will cause it to fail.   

So to summarize....  Take red HV wires off of the function switch, and solder them to some normally open contacts of a good relay
                             Tap some 6 VAC filament voltage from the adjacent tube and run it to one of the now open lugs on the function switch
                             Run a wire from the other open function switch lug to the relay coil (make sure the relay coil voltage and type match what you're sending to it...eg. 6 VAC).
                             Ground the other side of the relay coil.

Simple, and just moves the sparking to the relay, but it will save your function switch.  Those are really hard to find, and a miserable job to change out.

Cheers.

   
 

[K8AXW]

Not to nitpick, but one reason K3STX took a detour through the tall weeds is that he assumed a chassis is always negative. Usually is, but the DX-60 bias supply is an exception. Likewise, the assumption that a Twist-Lock electrolytic can usually be mounted directly to the chassis because it's at DC ground isn't always true.

On some newer stuff like audio gear and power supplies (IIRC) it has become fashionable to establish a single point ground which might not be tied to the chassis. The chassis could be at AC wall socket "green wire ground" for safety, but the DC supply has its own ground. Basic concept is one well-defined point that's absolutely at zero potential including noise. Audio amplifiers using this technique (allegedly) do have a lower noise floor / wider dynamic range and you'll see ground wires from every sub-section of the chassis connected to that single point.

[/quote/]

5UP:  Excellent and correct information.  One practice that has kept me from making the same mistake WYZ made is to replace components exactly like I remove them, including orientation.  Of course there are exceptions to this but for the most part when replacing like components..... they go in as they came out.  No need to concern oneself with what is ground and what isn't, as well as mutual coupling and lead length questions.

Same with rewiring the components.  I've found that whenever I disconnect multiple leads from a component, there will be a family emergency that takes me away from what I'm doing.  Without a scratch pad drawing of what came from where, I find myself in a world of crap!

Not to nitpick...... but a FWIW thought.

Al - K8AXW

[K3STX]

Hey guys,

Veering off a little, but DO THIS.................

Take the two red HV wires off of your function switch and put them on the normally open lugs of a good relay.  Where the red HV wires used to be on the function switch, run some low voltage AC (or whatever you can steal from an adjacent component....I think I tapped some filament AC from the speech amp tube) to be switched with the function switch, and then to the coil of the relay.  That will take away the HV sparking from your function switch.  The HV inrush into the big elect. caps produce a terrible spark that pits and corrodes your function switch contacts, which will cause it to fail.   

So to summarize....  Take red HV wires off of the function switch, and solder them to some normally open contacts of a good relay
                             Tap some 6 VAC filament voltage from the adjacent tube and run it to one of the now open lugs on the function switch
                             Run a wire from the other open function switch lug to the relay coil (make sure the relay coil voltage and type match what you're sending to it...eg. 6 VAC).
                             Ground the other side of the relay coil.

Simple, and just moves the sparking to the relay, but it will save your function switch.  Those are really hard to find, and a miserable job to change out.

Cheers.

   
 

I have read of this mod, I will do it!! You explain it so simply that even I am unlikely to screw it up. Now to find a 6VAC relay that can handle the 300 or so volts (Rat Shack, here I come!).

paul