That 2 pill driver is AB 1, 2 and 3 biased so I know that be some clean burd wattz. It's running off that 3 amp radio shack power supply that it's sitting on.
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
-
The Retevis Holidays giveaway winner has been selected! Check Here to see who won!
Machlett 3+500zg tubes
- Thread starter 552fl
- Start date
He's an AM guy that lives and dies by the RF meter. If it's not pegged all the way over then something is wrong.
He's an AM guy that lives and dies by the RF meter. If it's not pegged all the way over then something is wrong.
If only AM guys were obsessed with watching the watt meter SSB guys wouldn't say uhhhhh so much. People use ssb because the same finals would have to be ran at lower power in AM mode.
Here's what we use for 11-meter AM hot-rod operators.
The coil is #14 copper, three turns wound on a half-inch diamter. One 100-ohm 5-Watt carbon-film resistor inside, and another one in parallel alongside it. The long "tail" on each is to make it flexible enough to remove and install tubes without damaging the solder lug at the top of the plate choke.
Looks crude, but driving the amplifier hard produces a lot of harmonic energy. The parasitic choke will trap enough of this harmonic energy to overheat and cause the original 2-Watt part to fail, usually with a crack down the middle.
And if your main interest is sideband, you won't be driving the SB-220 hard enough for this solution to make sense.
But the nichrome suppressors will probably overheat if you use the SB-220 as an AM hot rod.
73
Here's what we use for 11-meter AM hot-rod operators.
The coil is #14 copper, three turns wound on a half-inch diamter. One 100-ohm 5-Watt carbon-film resistor inside, and another one in parallel alongside it. The long "tail" on each is to make it flexible enough to remove and install tubes without damaging the solder lug at the top of the plate choke.
Looks crude, but driving the amplifier hard produces a lot of harmonic energy. The parasitic choke will trap enough of this harmonic energy to overheat and cause the original 2-Watt part to fail, usually with a crack down the middle.
And if your main interest is sideband, you won't be driving the SB-220 hard enough for this solution to make sense.
But the nichrome suppressors will probably overheat if you use the SB-220 as an AM hot rod.
73
Nomad I know this is an old post, but I wanted to know if 3 watt resistors would be durable enough? Is there enough difference to be concerned about?
Thanks!
Has more to do with how hard you are on it. The harmonic energy from driving the tubes too hard is what makes it necessary to use beefier resistors. This is a common side effect of the way AM operators treat their amplifiers.
If you operate the amplifier on sideband, below the overdrive level, the original resistors hold up okay. The 3-Watt parts are bound to be good enough. And if you see them showing signs of high temperatures, you're dogging the amplifier too hard.
That's what my customers like to do.
73
If you operate the amplifier on sideband, below the overdrive level, the original resistors hold up okay. The 3-Watt parts are bound to be good enough. And if you see them showing signs of high temperatures, you're dogging the amplifier too hard.
That's what my customers like to do.
73
Thanks for the reply, Nomad! This is definitely not a amp that I run on sideband. I'm trying to determine what's going to be a good driver that will match with it, be it tubes, transistor, size, etc. I want to run as comfortable and consistent as possible with minimum troubles! Btw, we're talking about four 3-500Zs, js.
