>G'day Guys,
>
>I've had a few thoughts on the recent thread about filament inrush. People
>were suggesting all sorts of methods including inductors, specially wound
>transformers etc.
>
>Nobody seemed to pick up on the most glaringly obvious method that has been
>around for quite some time and has proved to be the most effective method
>of filament and ht supply startup.
>
>Those of you with an Emtron amplifier in the shack will know what I mean.
>It has been used in power rectification equipment. and even washing
>machines with great success.
>
>I am referring of course to the use of triac control start up circuits.
>For a few bucks worth of components you get the best soft start for both
>the filament and your ht supply.
** One DC relay plus one or two resistors makes a step-srart that's
fail-safe, and it happily step-starts every transformer in the amplifier.
[Figure 1 on my Web site]
>
>At switch on, my Emtron DX-2 takes around 4 seconds to start up the power
>supply. Now you try to tell me that this is not better than all the ideas
>we've seen on the subject in recent times. It just has to be better than
>the old resistor and relay and your super wound trannies and AC analysed
>inductors and all that stuff.
** Super wound/current-limiting transformers are no good for HV
transformers, only filament transformers.
>
>I don't claim to be very clever in this area myself. I'm just a lowly
>telecom technician with a Diploma in Electronic Engineering. I'm not a
>power or rf engineer and all I ever knew about AC analysis etc is long gone
>from my brain. I just know that when I switch my amplifier on each day when
>I enter the shack, that all the expensive bits inside it are well protected
>from any sort of stress.
>
>Next time you are at Dayton, have a look at the Emtron gear. Take off the
>cover. Lift the thing up. See how solidly it is built. It's shipped with
>the transformer installed you know. Ask about the ramp function slow start.
>Ask about the screen regulation. Ask about the tube protection. Take a good
>long look and then go and take a look at the new Ten Tec and all the other
>amps. Make your comparisons.
>
** Do Emtron amplifiers use a filament-type tube or a heater-type tube?
I know of no heater-type tube whose mfg recommends limiting inrush
curent.
>There's more info available at http://www.emtron.com.au/
>
>73, Alek.
>VK6APK
>
>ps: I have no interest, pecuniary or otherwise in Emtron. Just a happy user.
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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