PM cuts thru static better?

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Shane
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PM cuts thru static better?

Post by Shane » Fri Feb 05, 2016 11:49 pm

The discussion on static brought to mind something I have subjectively noticed when there are electrical storms nearby. The solid state transmitters, using newer modulation schemes (I think BE uses class E) don't seem to cut thru the static as well as the old plate modulated rigs.

I notice this when we switch to the tube rig as a storm is approaching. The static seems somehow quieter. So I wonder if these "new-fangled" modulation methods are responsible for this phenomenon.

OR is it as simple as the foldback, which would happen more or less simultaneously with a close strike, merely allowing the static to be heard better. I can hear the foldback, if it's deep enough, by an increase in background noise during the foldback. A very interesting sounding effect which the tube rig doesn't do - no foldback circuitry. But could this explain why the plate modulated rig is a lot easier to listen to during a storm, at least in my experience, my first situation where I could compare hollow and solid state on the same station?
Mike Shane, CBRE
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Deep Thought
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Re: PM cuts thru static better?

Post by Deep Thought » Fri Feb 05, 2016 11:59 pm

PWM doesn't make it past the DC stages so I'm not sure how it would influence the susceptibility of lightning noise. Most PWM transmitters can maintain higher modulation density so you'd think they would be better at masking it, but I think you hit on the actual cause...instantaneous foldback. The old tubers would just plow through it, burning up whatever got in the way. :mrgreen:
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Shane
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Re: PM cuts thru static better?

Post by Shane » Wed Feb 10, 2016 2:44 pm

The BE AM1A does something different from other solid state transmitters of the early 2000s but I can't recall what. The thing that was unique about it was it would remain within audio specs all the way down to 5 watts whereas the others we were looking at would get out of spec below 100 watts.

Anyway, thanks for your thoughts again, Mark. I'll have to reduce the time threshold on the foldback alarm to see if I can catch some of these next spring. Currently the remote control is set to leave us alone unless the rig is in a foldback condition for 2 seconds or more.

That has been long enough for us to miss some of these events. After trying to catch these I think I may consider a time delay of 0.5 seconds. Unfortunately, about the only way we can tell if the tube rig is fussing about the condition is to hear it happen on a radio or air monitor (or call the R/c and hear or watch the antenna current ballooning up and down). And with the 2 second parameter on the foldback alarm on the BE sometimes it's the same thing - we have to hear it sputtering.
Mike Shane, CBRE
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