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Title: Heath Chippewa Post by: VE3AJM on January 29, 2015, 06:08:03 PM Curious if anyone on here has modified the amp for class C plate modulation? Looks like the plate tuning cap and any components that would have modulated DC on them, would have to be upgraded at least. I have a line on one for relatively cheap.
Al VE3AJM Title: Re: Heath Chippewa Post by: flintstone mop on January 29, 2015, 06:18:09 PM How's about SCREEN modulation???
Fred Title: Re: Heath Chippewa Post by: VE3AJM on January 29, 2015, 06:36:28 PM Yeah..ts a possibility Fred. It wont be LOOPY modulation though. :)
Al VE3AJM Title: Re: Heath Chippewa Post by: John K5PRO on January 31, 2015, 02:40:45 PM I have one and have considered the same idea when I picked it up a decade ago. Fellow had several of them, I took the worst looking without power supply. Later I found the KS1 matching power supply in California. Once I looked at one in Seattle while I happened to be there, but it had been converted to grounded grid and I didn't care for that, plenty of smaller amps can handle that. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
So you are correct that the plate tuning cap would need beefing up, with wider spacing unit. It already has a healthy cooling package. Since screen voltage comes from a regulated supply (VR tubes in stock, a separate transformer in mine), it will need to feed via a small choke or resistor to 'self modulate'. And you'll need to play with grid bias. Chippewa is my favorite big iron amp, it is quite rare and built so much heavier than the Warrior ever was. |