Search results

Talking about those resistors, it's been a while since I worked on a Texas Star, the last was a DX1600 in 2004. If I remember right those are the Bias resistors, I was thinking 1.8 and 1.6 ohm, maybe I am not remembering it right. I think I have some of those around here.

Dug out some old Class C 2SC2879 2 pills I built back in 2003. Did not realize they are non Red Dots till I opened the amps up. They are. So what should I do with them? I'm not planning on building or running any "Comp" boxes, I'd hate to build something with these when I could sell them...

Yeah whatever I saw was something from Amazon that had a schematic with it, showed a 2 x SD1446 amp. Maybe that was an older like KL-203 without the P, hell I don't know. I have never owned a RM Italy amp. Worked on a KLV-500 or whatever it's called once, many years ago for a guy, base amp...

Oh wow, that's crappy. A friend has one, and he sent me a schematic, it showed SD1446's, but it was not in the box with his amp, it was something he downloaded online. I was wondering why only 100W output, a pair of SD1446's good for 150W or more and will take more than 4W drive (in a pair).

Thanks Andy. Makes sense.

What are the power transistors in a KL-203 or KL-203p amplifier? I thought it was a pair of SD1446's, but someone said mosfets???

Looks like his meter was out of Cal. Not sitting on 0 (the bird meter, not Daiwa). I'd go for 1500-1800PEP from a monobanded 3-500Z amp at 3KV and glowing like that. Can't say how long tube would last though. Run that amp at 1000-1200, last long time.

The one good thing about the low gain stages SHOULD be durability. However due to it being FETs, that half-way goes out the window. FET's will take a lot of abuse on the Drain/Source, but the Gate is a different story. If that gate signal gets screwy, pop goes the mosfet. I only blew the...

Question for the tech savvy, is the 2.2uF electrolytic cap enough cap for the bias output? I mean caps are cheap, and small these days, was thinking why not use a 10uF or so cap there, or even a 4.7uF...

Yes in the Palomar amp using this Bias circuit the 7805 had a little TO-220 heatsink attached to it. Having dealt with these 7805, 7812, 7815 type regulators ALOT in my past lines of work, they take the dropping voltage really well, even without a sink, even in fully encapsulated package form...

Glad y'all found this circuit useful. 73's -443

Yep. I bought these amps from a local Palomar builder 11 years ago, for I think about half or less than half of what they cost now. I may have been given special pricing though, was a friend. I had a 250FET and a 450FET. Used one to drive the other LOL. My feelings about these... If I don't...

I did get in touch with RocketBox. Just thought I'd update.

Though I don't want to get off topic and also go into information overload in this thread, just for reference, with the 723 regulator circuit above, this is the Dual Bias LNA schematic they were speaking of in the document.

Also I did read over the Peakaboo thread (where is he these days? been a while since we spoke), but found lots of discussion, no schematics. I was intending this circuit as an alternate to the "Quick and Dirty Bias" sticky post. Being that this is a Regulated Bias design, "should" be better...

I read over that, but it was all about unregulated, sandbar resistor/reverse diode bias, which works "ok", but isn't regulated.

Thanks guys for the input. I find it useful and I am sure someone else here will too. Some of my thoughts: Question about the diodes, the diodes in this circuit, are/were not mounted near the power transistors. I wasn't sure if their function was to kill AC/RF that gets into the Bias...

You are welcome. I am hoping to receive some input from some of the more experienced amp techs here on this circuit before anyone tries it, just thought it might interest quite a few looking to do something other than the brick/sandbar resistor and reverse diode Bias thing. I would think this...

Was reading over posts here about simple amplifier biasing to otherwise AM/FM only Class C amplifiers, by adding big resistors and reverse diodes, the normal, easy, but works, way to do it. So I thought I'd contribute this, for opinions, options, upgrades and applications. This is a crude...

I see on their Facebook page they were "testing" a 1000XL version of this low gain mosfet amp. My confusion is, that I "thought" I knew the guy who started "RocketBox" like around 3-5 years ago, but I could be wrong, or maybe he recently sold it. Not giving names, just initials, here, JDG...