--- In ham_amplifiers@..., R L Measures <r@...> wrote:
RICH SEZ...Correct. Jim. My thinking on NOT using a fuse holder is
that if the fusing element blows, the reason is not a defective
fuse, it has to be the whatever that caused the fuse to blow, so a
new fuse is not the total repair. Thus, when the fusing element
blows, the amplifier has to be disassembled anyway to find the
real problem, so a fuse holder would be of no advantage.
### Gimme a break ! The grid fuse could blow for several
reasons.... like SKY high swr... accidental overdrive....
underloading, both..... OR if the HV fuse blew open [and with amp
being driven, the grid current will wrap around the peg].
## once the reason for the grid fuse blowing is known.... it can
be quickly replaced... in mere seconds flat. Ditto with a
cathode fuse. A little longer to replace either of the HV fuses.
### I can stuff a screwdriver into the HV compartment, grnd
anything you want, short out caps, short the grid to the
cathode... run 15 kw into a dead short, wide open,,, drop a wrench
across the 240 v input, have the big Dayton blower crap out, lose
air to the tube , lose commerccial AC power from the street,
have transients, spikes , surges coming in off the street,
overdrive the amp, underload the amp, etc, etc... and you STILL
CAN'T blow anything up. I can even lay a dead short across the
diode FWB rectifier board.... and not take out any diodes.
### I can also short out the fil xfmr, or short out the + 120
vdc supply for the sped up vac relays, or short out the +12
vdc for the plate choke relay.
### My goal was to make it [RF deck + HV supply] 120% BULLET
PROOF!! Next step is to add the spark gap across the Vac load cap.
[heck a spark plug in open air.. set to arc at 1.7 kv will work]
We might add electronic grid + plate overcurrent protection
later on... + a HV sensor [which will inhibit TX... with low, or
NO hv present].
### The beauty of HB designs is.... you can easily add any or
all of this stuff in... at any time.... and it's all dirt cheap....
just like copper tubing.
Later... Jim VE7RF
