New Amplifier - ULD Extreme

[ostripper]

Originally Posted by VHF man

Hi OS

The f14 ferrite needs to be in series with the vas emitter and preferably as close to the vas device as possible. If you use a small emitter resistor on the VAS then the f14 or F25 bead could be installed over the resistor lead closest to the VAS transistor.

Dave VHF

So integrate it with the degeneration resistor that is VERY close to the main VAS device (R17 below) ?. Insulate the resistor lead and pass 2 turns through the f14. Just to be sure ... is this a f14 ??


BTW , you realize this amp has "magical sound". I can't get over it ... had to get new tweeters and mids (below 1)to fully realize just how accurate it's sound was. Near perfection. I will share the final design (below 2 - r25 is just to test CCS current , not on real amp)... 0 thump (not even a "glitch" on the CRO) , 0 offset (0c - 60c) , can't be overdriven , and 100% awesome sound. It will run from 10V to 80V rails maintaining it's 6mA CCS current.

I've built every voltage stage out there and this one stands out. I can swap stages in 30 seconds , so I KNOW.
OS

[Ian Finch]

Os, those TV baluns look the part, grade-wise. If they were for VHF reception, rather than just UHF, they'd be suitable. If you have access to the ARRL handbook in some form, it's usually a great guide to ferrites. I see there's some guidelines there too in the catalog you posted. The 6-hole "bead" Dave is using is, in my example, 6mm dia. x10 long.

[VHF man]

Originally Posted by Ian Finch

Thanks for the comments
A great opportunity, eh? I did the same with ACE Radio in the late 1980s. Indeed, I have a number of those 6-hole formers and wired ones too. There's quite a bit more material in those than your average bead, however. I imagine it would take 2-3 beads of say 3.5 x5 mm to approach those big'uns. It's just well I asked.

Yes they are probably 3x standard beads. I will set up a bread board test cct and sweep Z over 1-50 MHz. I should also really use a 10mA dc bias to better simulate a VAS environment.

[VHF man]

Originally Posted by ostripper

So integrate it with the degeneration resistor that is VERY close to the main VAS device (R17 below) ?. Insulate the resistor lead and pass 2 turns through the f14. Just to be sure ... is this a f14 ??OS

If it's sold as a vhf grade former then yes it's probably what I call F14.
It's a specific blend of nickel + zinc that's effectively lossy > 10MHz.

NAL F14

[Ian Finch]

This would seem to be the equivalent part in the US. The nearest standard Ni/Zn grade is 43 and fig. 1 (unwound) appears identical. As Dave suggests, a few smaller, plain beads may suffice. I guess we'll hear shortly.

Fair-Rite Catalog | Wound Beads

[Harry3]

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