Be careful fitting faster transistors.
I replaced some output transistors with new transistors and the amp oscillated badly.
I had to put a bigger capacitor in the VAS to slow it down.
I have also found you sometimes need 10R resistors between driver transistors and output transistor bases when fitting new transistors.
I replaced some output transistors with new transistors and the amp oscillated badly.
I had to put a bigger capacitor in the VAS to slow it down.
I have also found you sometimes need 10R resistors between driver transistors and output transistor bases when fitting new transistors.
On-semi's MJL21193/4 are nominally "slow" with an Ft of 4MHz but really tough and with much better gain linearity than their old TO3 types. Expensive? Possibly but then what price on reliability?
The originals are 20 mhz, so I think 4 mhz is too slow .. more a 70's /80's thing whereas the M-501 was built late nineties. I think the 30 mhz ones will likely be drop in replacements. 2SA1943/2SC5200 ... I'm going to have to re-do this thing for the driver and possibley some of the signal transistors, but no time right now.
Anyone correlating the current presidential election meltdown with amplifier theory? Anyone else notice that there's no negative vote on the ballot (killing proper negative feedback) and that the gain factor from president to population is roughly 1:100000000 setting us up for bad-a parasitics?
Anyone correlating the current presidential election meltdown with amplifier theory? Anyone else notice that there's no negative vote on the ballot (killing proper negative feedback) and that the gain factor from president to population is roughly 1:100000000 setting us up for bad-a parasitics?
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