More than many. Can't remember a tetrode or pentode class C final that didn't modulate plate and screen both.
Screen-grid voltage has more control over plate current than the plate voltage does. Holding it constant would be a big handicap.
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Palomar Electronics Max-Mod. Spoiler alert!
- Thread starter nomadradio
- Start date
More than many. Can't remember a tetrode or pentode class C final that didn't modulate plate and screen both.
Screen-grid voltage has more control over plate current than the plate voltage does. Holding it constant would be a big handicap.
73
Let's not forget about rigs like the Heathkit DX-60 which only use screen modulation. It was also noticeably behind the audio quality of the DX-100.
Oh the beloved Maxi-Mod! They seemed to have disappeared as quickly as they came into play.
Mark @ Fine Tune CB is still touting them like they've been heaven-sent!!
From what I've heard, he and Eric seem to be pretty tight. Maybe he's the "exclusive" distributor for the maxi-mod
I believe someone put a video out awhile back saying the “max mod” wasn’t any better than the TIP36c or even the Toshiba part. Well, the Toshiba part was marginally better, that’s what I think he actually said. But between the 3 there was really no performance gain at all.
You got some guys sold on that max mod though, no true data sheet for it or anything. The sand Jawa said it was better, my wife said bigger was better, so he must be right! Haha.
Heat kills. So why not just run the wire and take the load off the part? If the load is present then I don’t see how a larger case is making it any better, marginally better which can be explained with math. The man even said he’d send you the data if you cared to look at it but they just don’t want to listen to him.
You got some guys sold on that max mod though, no true data sheet for it or anything. The sand Jawa said it was better, my wife said bigger was better, so he must be right! Haha.
Heat kills. So why not just run the wire and take the load off the part? If the load is present then I don’t see how a larger case is making it any better, marginally better which can be explained with math. The man even said he’d send you the data if you cared to look at it but they just don’t want to listen to him.
You mean me.?!?
I've been just about the most vocal person against the "snake-oil" claims of the infamous Palomar "Max-Mod" device., ever since their introduction to what I call the "up-sale" (adding / padding a customer's bill) "marketing-ploy" of "pushing" them as some type of "God-send"and have always been against such practices.!
And especially when it comes to those folks that are concerned about the large amount of "waste-heat" that can be generated by the main AM power regulator / modulation transistor., I had posted a long / detailed description of how to very simply quell the fears of those who know how VERY hot that device can get at high dead-key / carrier levels, and even attached a few photos of the simplicity to rectify the problem., especially since virtually all manufacturers mount them under the radio's outer housings / covers.!)
It was waaay back in post #81 of this lengthy thread, and is again linked here from my Klein Communications FB page, which is entitled:
"The AM modulation / Power-Control, Pass-Transistor"
Respectful regards,
Eric Klein
Klein Communications
Klein Communications | Buckhannon WV
Klein Communications, Buckhannon, West Virginia. 2,301 likes · 18 talking about this. Repair of Commercial FM 2-Way Radios, CB Radios & Amps - Design & Repair of Power Back-up Systems
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No, I don't even know you dude. I was responding to a comment about the Jawa, and his relation to Eric Lewis. I have no idea who you even are.....You mean me.?!?
Don't be like the mainstream media
Ahh, yes, now I know who ya mean, as I too, am quite aware of "Mr. Lewis" and his (and late father's) tendency for the re-banding of some items.!!
As far as any similarity of me to "main-stream-media" is concerned., I don't believe that my present BitChute channel (which was created just before the "Great-Purge" of other YouTube channels like mine) would be as far-away from ANYTHING "main-stream" as one could get.!!
WVradioman
Howdy all., "WVradioman" (Eric) here., from my YT channel (https://www.youtube.com/user/WVradioman) and my complete up-load list (https://www.youtube.com/playlist?list=UUvsxRjHXrPdAgCinyKBYAMA) with an explanation for my presence here, and why I bel…
www.bitchute.com
Simple facts. The 60 watt transistor biased up to provide 6 volts VCC at 1 amp, will be dissipating 6 watts of heat into the heatsink. The 150 watt part biased up to provide 6 volts VCC at 1 amp, will still be dissipating the same 6 watts of heat into the heatsink. Heat disapation is a direct function of current through the part, multiplied by the voltage drop across the part. Changing the pass transistor part number has no ability to alter heat disapation. It only impacts reliability.
But a larger package with more surface area in contact with the heat sink will exhibit a lower temperature rise.
Heat is heat. The heat sink will still get just as hot. The transistor's temperature will always be higher than the heat sink. But the larger package will let the transistor breathe just a little easier than the smaller-package part. For years we used the 2SA1302 transistor for just that reason. It has a higher current rating than the 2SA754 used by RCI before lead-free, but the bigger package made it more reliable for a sideband operator. Current rating is irrelevant once the die inside the transistor reaches meltdown temperature.
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Heat is heat. The heat sink will still get just as hot. The transistor's temperature will always be higher than the heat sink. But the larger package will let the transistor breathe just a little easier than the smaller-package part. For years we used the 2SA1302 transistor for just that reason. It has a higher current rating than the 2SA754 used by RCI before lead-free, but the bigger package made it more reliable for a sideband operator. Current rating is irrelevant once the die inside the transistor reaches meltdown temperature.
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How does the larger package make it more reliable for the sideband operator, when there is no voltage drop across this part in sideband and the full 12 volts is applied to the drivers and finals? This part only affects modes with carrier, where the VCC is less than 12 volts.
Good chance the only reason the sidebanders were popping 2SA754s was from turning the ALC too high after they got the radio home. Never bothered with an analysis. Back in the 90s we had callbacks from failure of newly-installed 754s, but only from sideband operators. Simply upgrading a chronic-failure component may be a kind of knee-jerk solution, but it worked. Never got around to analyzing the arithmetic of the issue, just the cause-and-effect side.
Yes, correlation is not always causation. Sometimes it's all you have to go on.
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Yes, correlation is not always causation. Sometimes it's all you have to go on.
73
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