Who in there right Mind?

[N8ETQ]

     Found this on the primary side of power
xfmr in an AL-80A..  Amazing!  The guy even
strapped another 10 ohm 10 w across it after
this one melted!  One Dam tough "R"...

     I  found a bunch of bad diodes..

  Never saw one melt like that.

/Dan

[KL7OF]

Looks like it melted because of  RF......not current overload..

[N8ETQ]

 after a little more "pokin'" around it looks like
part of a Harbach Soft Start install gone Wild...

   I think you need to get a diff. R for 110VAC on those.
Nice clean little amp. Hope the guy didn't ruin it.

    God never intended for a medium power amp
to run off 110 VAC.  Can I get an "Harrumph"?

/Dan

[KA9EGW]

Harrumph!

[WQ9E]

When anyone installs one of these mods there needs to be a fuse that will open if the relay fails to short across the resistor after the "soft start" period.  I have seen a couple of cases where damage was done from resistor shrapnel with this style of modification. 

[N8ETQ]

Good Idea Rodger,

   An appropriate SLO-BLOW in series with the "R" that
also gets jumped out by the relay should do it easily.
This could be the first time I've used my Tektronics
current probe!

Thanks,

/Dan

When anyone installs one of these mods there needs to be a fuse that will open if the relay fails to short across the resistor after the "soft start" period.  I have seen a couple of cases where damage was done from resistor shrapnel with this style of modification. 

[WQ9E]

Dan,

You are welcome.  If you are rebuilding the circuit you might also consider using a relay with an extra set of contacts for the step start circuit and use one set  of contacts in series with the T/R line so that the amp cannot go into transmit mode until the step start relay closes.  I set up my homebrew amplifiers this way.