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Discussion in 'General CB Services Discussion' started by 357, Jun 14, 2018 at 7:34 PM.
Thats about right in price tech- nine used to be or is still on you tube he makes the best amps around.
C-class as I see? Bummer.
I think TechNine only builds class C amplifiers. I've never seen one of his that had bias resistors installed .....
If you need to liquidate the (old worn out, beat up, butchered) Golden Eagle 750 to raise funds for this beautiful piece of electronic art, I can help you!!
That is such a wasteful inefficient design.I would love to have a friend nearby that had one so I could look at all the impedance bumps inside the unit. pulling out of the grommet and away from the board.
Instead of proper grommets, he is using 3 wire ties on the end of each huge cable to attempt to keep it from.
The power wires do not have a good physical connection and the soldering is not on a large enough surface area to do a good job of resisting vibration and pulling on the wires. The B+ has very little surface contact. solder alone is not enough for a wire of that size and weight!
Look at all that coax inside the box and the huge resistors floating in space with long leads!
I would rather have a mix of 4, 5 and 6 transistor amps than anything with 32 or more. I could see going as hi and 15 transistors if it was going to be used as a base legal limit amp and you wanted it to run cool. In a mobile, though it is just funny!
But it's pretty to look at...I can stare at things like that all day - but my XYL would not understand...If they just put mirrors on both end panels - and - at the right viewing angle - get an infinity amp...
Boy I gotta' stop staying up so late at night - LOL!
Personally, I think his construction is very well done. The B+ lead appears to be wrapped to secure it to the B+ rail before it was soldered. The negative cable is securely soldered to the ground plane. The resistors are mounted off the board on long leads to help promote air circulation and cooling. Exactly the way I would have done it.
OLT ... show us something you've built.
Yes it is pretty to look at but how often are you going to leave the cover off and put it some place you can see it? Do you put things like this on your coffee table or the wall? Thankful I have never gone to a muesem that has had such on display as modern art behind glass. That said I am not a fan of the Mona Lisa either! LOL
I think a nice big strong breaker bar or a pair of pliers can be sexy when they do a fantastic job at what you need them to do! Nothing worse that a terrible tool! Beauty is in function even more than the visual clues.
I really do not give a toot about how my amp looks especialy under the cover. What I do care about is oscillation, biasing, protection circuits, rated output power, lack of harmonics and durability. My Camry is 15 years old and nothing under the hood besides oil, airfilters, coolant, spark plugs, 1 battery and one belt has ever been changed. 1 Set of front struts. She is just getting some rust I will need to fix soon. As much as I hate FWD cars and 4 cylinder engines this car is beautiful because of what she does with ease. Never failed to start and has never broken down. All of my other Toyota's have been the same way. Boring as can be and not the sexiest to look at but got it where it counts.
I expect even more from my electronics than I do mechanical machines. As you have figured out I am disappointed all the time by a good many things! So these "builder" amps that can not last a few months let alone a decade of daily use with out failing no matter how pretty they might look or the power output claims or the like they are just highly polished turds. You know kind of like costume jewelry might look pretty but it is utterly worthless much like fools gold! If I can not reasonably bet my life on it when TSHTF I do not want it around me becasue the false sense of security will only lead me to falter!
Unlike 70% of America I actually have standards that fairly stationary and are not based solely on my beliefs and opinions! LOL
In a mobile application you should not have a 32 pill amp where you can see it and you should definitely not have the cover off it! LOL Generally we do not want debris to get into it and usually space is limited and a 32 pill takes up some space. On top of that in an accident if it is not secured well it would become a missile and take you out!
Maybe that amp should have tanning bed bulb in it! LOL
Maybe lexan cover and you can mount it to the hood or the head liner.
I also do not get the custom paint jobs or decals when you can not see any of that unless it breaks and you need to get it out of the trunk! LOL
That is one of the reasons I like 102-108 inch whips. Bullet proof practically no other CB antenna on the planet can take as much abuse and cheap compared to most CB antenna's! No amount of sexy can replace utility and durability!
Well I guess in a way, we're both right...
(Didn't anyone catch the reference "infinity amp" - Avengers - GROAN...)
Now I will tell you I got my XYL (a little bit upset) CONCERNED over the fact that I had removed some wedding photo Album page protectors to use for my schematics of Cobra 148 and her HR2510.
It Didn't settle too well with her...
Now, I'm going to speed this up a bit so you know - because we do see things in a different "light"....
And so it should be,
I have known of people that have placed the little "black lite" night light fluorescent bulbs on their "twins" and ran around at night using the TS 250 or whatever they had, keyed up to look flashy on a cruise night.
And sometimes I see radio's built so pretty - it's a shame to have to take them back out of the box to use them - but that's why I am still alive today, because I protected my XYL's investment too - else messing with her Wedding album - you might have wound up in a serious world of hurt.
Sometimes the radio looks better if it sits of the shelf, for I do know some "flashy" stuff out there that is all fluff no work - at least it lights up...but that's about all.
And sometimes - the only good thing it has going for it - is it's good looks.
Check - Check
:+> Andy <+:
... You know you're a CB'er when...
... Your radio lets you watch it's show, while you play with it's knobs...
Toshiba BJT's ? We're all chumps...
The first is a DC to 54 SDR @ 500mw
Next is it's 300w amplifier. Note the filter section.
Then the big brother 1.8-54 Mhz for 2xBLX188XR .
I'll spell it out in plain english.
Amplifier Class Description Conduction Angle
Class-A Full cycle 360o of Conduction θ = 2π
Class-B Half cycle 180o of Conduction θ = π
Class-AB Slightly more than 180o of conduction π < θ < 2π
Class-C Slightly less than 180o of conduction θ < π
Class-D to T ON-OFF non-linear switching θ = 0
Lets get some fundamental myth out of the way .
Solid-state amplifiers cannot be class "AB1" or class "AB2". A bipolar transistor amp cannot be a sub 1 or sub 2 class because they do not have grids to have or not have grid current. Solid-state amplifiers have bases or gates, and a bipolar transistor always has base current.
Class AB does not mean the amplifier is linear. "Linear" in the context of amplifiers indicates a linear transfer function, or a transfer function that has the proper transfer function curve shape to minimize odd-order intermodulation products. A linear transfer function generally means the output power level tracks the input power level in a way that does not cause excessive 3rd, 5th, 7th and other odd-order mixes. Only odd-order mixing or distortion produces annoying splatter.
The bias current can NOT remain steady because the bipolar requires a change in base current to produce a change in collect current.
If the bias current remains steady with varying drive, the amplifier will have gain compression.
If the VOLTAGE supplied to the bias system remains fixed at a level that produces the correct Ic for the device junction temperature, the amplifier will not gain compress when the exciter power rectified in the EB junction tries to add negative voltage back into the bias supply.
If the current is regulated, the bias will go negative as drive is increased.
That's why high power transistors can not be correctly biased without an active bias system that maintains constant voltage with a very low bias dynamic source impedance .
FET's, because they have no gate current (hopefully), require only
a regulated voltage source of almost any impedance.
I'd like to thank Tom Rauch and https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html for the text and graphics
Sławomir Kleczyk for the photos.
I'd rather convert DC/DC to get the necessary voltage and use a modern output device .
Directive 2002/95/EC, originated in the European Union in 2002.
This was the initial death knell for the Toshiba 2SC2879. Production modifications were made within the year.
All applicable products in the EU market since July 1, 2006 must pass RoHS compliance. This killed 2SC2879.
Short version , lead free.
Long version Beryllium free.
Longer version is BJT's had outlived their design expectancy and the only market was HF radio. Toshiba threw in the towel and cut what was becoming a loss leader. This was sixteen years ago!
Then the imitators and outright fakes.
If you read this far I commend you because all this remedial education is putting me to sleep.
Bias is not resistors , diodes or even a fixed source .
Class of operation is determined by bias
BJT's are dead
LDMOS or MosFet
Damn I long for a time when tubes were a simple affair of a few volts here and there and a tank circuit out of the handbook.
As you were
Now I don't claim to know anything about anything but I can imagine all the work that went into putting this together. The detail looks very good and if I built an amp I would want it to look like this even though the lid goes on I would know it. It would have to have a metal lid to keep the RF in right? I can't imagine how someone would go about matching all the double pill sections together. Or is it just "put it together and it is what it is"?
Yes matching is important but well documented.
Yes it all gets RF tight enclosures.
A candy store.
Ya gots ta pay ta play . Never said the high life was cheap.
What would you rather do ?
Four times the current at 14V with obsolete devices , at half again the IMD, at nearly four times the dissipated heat load?
And melt it down and build it back up repeatedly
Spend it once and get it right.
I see it as a know brainer...
Guys when I go off the deep end on a rant I do not think I am right! LOL I know I am a nut and other peoples opinions are just as valid as mine. Now when something is based in fact though that does trump opinion even my own! LOL
I am glad you guys put up with me! LOL
Actually, for me, it would be a very expensive mirror but a parts bonanza when I needed to scavenge a part of two.
Else all it would do is sit across the room laying flat with the mirror facing me, then to have it light up with some NEON tubes buried alongside the board as I "chat" would make an impressive display. Or, don't even bother using it with a radio - just put a neon night light in it...
Heck don't need to key up the amp - just "model it" and sell it as a kit for kids so they can become the leaders in Amp Building someday...Hello Lego?
I guess if someone went to all the trouble to make it look so pretty, why put a plate over it? Just let it shine or even better make up a "Cherry patch" of Sweep Tube amps and watch their glow and arc all night - at least during the winter months you'd have light and heat in the same box. Or centerpiece if you want to cook your dinner on the table...
:+> Andy <+: