On Wed, Feb 14, 2024 at 05:45 PM, Amp Guy Llc wrote:
I would like to point something out before I take my wife out for a Valentine¡¯s Day lunch and then get to work
Jim¡¯s choke will be tested at a high duty cycle 100 percent. Theirs a big difference between a ssb type duty cycle , vrs am long rag chew or a data mode type.
Really Apples to oranges.
There are A LOT of guys running am and other high duty cycle modes. High power pa¡¯s
Once the chain and sprockets finally arrive I¡¯ll be back on the 160-15 meter pa and then can map out the capacitor capacitance to turns ratio and finish tapping the output pi network coil. Look forward to getting back on it and showing it in operation.
I¡¯ll have to deal with the line drop issue prior to the test. So don¡¯t have a repeat of the 10kw 6 meter test.
73
## agreed.? Every newbie and his dog runs FT-8....esp on 160m.? ( all bands really, but most folks don't have good ants on the lower bands, and they also have high noise levels on the low? bands).? They go to bed at night, and meanwhile their xcvr / pc / amp is running full bore? FT-8 all night long.? Then they get up the next morning to see.....'how many? new countries' ...they...'worked'.? If I say the choke works good on SSB, somebody is gonna bitch how they overheated it on FT-8, hence testing it with a cxr, at least for 15 sec on, 15 sec off.... for 1/2 hr.? ?RTTY is even worse.?
## The issue with plate modulated AM is..... the B+ doubles with 100% positive modulation....and a helluva lot more with 125% to 150% positive modulation.? I can see all hell breaking loose with his? ( black dude, forget his callsign) pair of 4-1000's modulated by a pair of 4-1000's.? 5 kv now becomes 10-12 kv on peaks.?
## I think ( I might be wrong here), the black dude in Co had issues with the floyd choke...and I think on 160m plate modulated AM.? I think it drifted enough in uh value, that it affected the C1 tuning, putting the amp out of resonance a bit.?
## any plate choke is directly in parallel electrically, with the C1 tune cap. ( cold end of the plate choke is bypassed to the chassis with real low XC bypass caps. IF the caps overheated, and drifted? higher / lower in value, it could affect tuning.
The C1 tune cap's? C has to be increased a bit over calculated values when on 160+80m? since the C1 cap has to also cancel out the XL of the plate choke.?
##? IE: the big choke from the 8K ultra measures exactly 180 uh.? With it in the circuit, the C1 tune cap has to be increased by 40 pf.? (and 10 pf on 75m).? With a bigger 360 uh choke, C1 has to be increased by? 20 pf? ( and 5 pf on 75m).? With a bigger choke to begin with, any change in value of the choke will have a lesser effect on the tuning.?
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##? I only saw a measured 2 uh drop, from 305 uh, down to 302 uh, after 2 hrs at 3.222 amps CCS dc current flowing.? ?Sounds good so far, but that test has no RF current flowing (which will be 1.25 amps @ 1.8 mhz).?
## This entire mess will get tested out soon enough.? ?I have a busy week, and the tweaked up version of Scotts new choke still has to be shipped out. (+ a pair of .01uf @ 30 kv disc? bypass caps).
