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Re: Supercapacitors - Possible anti-surge device to protect filaments/ heaters

 

Or just bolt a nice aluminum box from Bud Industries onto the L-4B/L-7 PSU front panel (bolt-on vertical or horizontal)
and use it to trick-out your PSU:

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AMAZON - BUD Industries CN-5714 Die Cast Aluminum Enclosure 10.81" L x 6.89" W x 2.64" H, Natural

Many other sizes available to suit your needs.

Stuff the box with all sorts of electronics, like the resistor for start-up.? Also add a power switch
that can handle the current surge.? Add a pilot light.? Add an HV voltmeter for permanent HV
readings:

image.png
AMAZON - Baomain Analog 85C1 DC 0-5V Rectanglular Panel Meter

image.png
AMAZON -?Baomain Analog 65C5 DC 0-5 V Round? Panel Meter

Change the L-4B/L-7 front panel switches from AC mains to 12VDC

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AMAZON - Rotary Panel Switch, 690VAC, 32A

Use control modules to sense and protect your amp against high SWR,

image.png
DXWORLD-E?SWR Module, HF, 6m, 2.5KW

Use control modules to sense and protect your RF deck and PSU transformer?against high temperature:

image.png
AMAZON -?12V Temperature Controller, -50 to 110C Degrees, WITH Display

image.png
AMAZON - 12V Temperature Controller, -50 to 110C Degrees,?NO Diplay

Even protect against arcing in your amp, antenna tuner, feedline, balun and antennas, any and all covered.
Key takeaway:? Arcing turns your amp/tuner/feedline/antenna into a Marconi broadband spark transmitter:

image.png
NASA -?Arc Protection System for High-Power RF Amplifiers

For the coupler, use the SWR module above.

You could even build-in a RaspberryPi to tie-in with your home's skeduler and disable your rig for
the times you've been assigned house chores.? Negotiate this feature for the funds to pay for all
this gear, and more!

Just my 2 Volts.

73 de Andrew/N5ASE


On Fri, May 23, 2025 at 9:17?AM Jim VE7RF via <jim.thom=[email protected]> wrote:
>On Fri, May 23, 2025 at 03:54 AM, Jim Shorney wrote:
>Or a NTC surge limiter in the AC mains side of the power supply.

That would work too...... but they have to be sized correctly.? ?They run hot, and have to stay hot.? ?IE:? no forced air on them, or their resistance will increase.?

The op did not tell us what tube or tube fils? he is trying to limit inrush current on.?

For stuff like my L4B's,? I do the step start externally.? ?It's just a 8x8x4 electrical box, (home depot)? with loads of knock outs.? ?2 x P+B / Deltrol? DPST? 30 amp relays, + a 20 ohm / 50-100 watt resistor.? ?I used arcol metal finned resistors since I had? a bunch of them.? No standoffs? required, just bolt em down.?

Small control cable? runs from the new? box on floor.....up to a small? mini box on desk, with 2 x mini toggle switches......one for each 120 vac relay coil.? ?Relay #1? applies the 240 vac. (On/off switch on L4B left permanently in the on position).? 20 ohm resistor in one leg of the 240 vac.? ?B+ comes up to 90% of normal.? ?Fils on the pair of 3-500Z's come up to 70% of normal brilliance.? ?Wait 2-3 secs, then hit toggle #2....and 2nd relay operates.? ?One pole on 2nd relay? shunts the resistor.? ?2nd pole on 2nd relay has the key line running through it.? ? IE: step start the B+ and the fils at the same time.?

IE: manually operated step start.? ?Amp can't be keyed until 2nd relay is operated.? ?Dead simple.? ?When? switching from SSB to lower 1900 vdc CW position, non issue.? ? ?When switching from CW 1900 vdc? back to the SSB? 2650 vdc position, I put the resistor back in the circuit,? then switch? from CW to? SSB, then? shunt the resistor.?

I have 2 x harbach boards in each L4PS, and each board has 8 x 330 uf caps.? ? The on/off switch in the L4B is a 10 amp slide switch buried below the rocker switch....and is flaky at best.??
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