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switcheable bias 1x4
- Thread starter bob85
- Start date
N
NewcastleBrownAle
Guest
Nice looking Bob. I see the bias transistors for each 2 transistor section(what trans. did you go with), but where is the supply for the driver? Did you pull off of one of the other two?
Also out of curiousity is this setup like the one used by skywalker(homebrew amatuer not the cb one) which is one I have posted before?
If the answer to the question about the design is yes did you try the same design with matched transistors and only one bias supply? I figure you could do so the only issues is if they are not matched.
Again nice work very clean.
Also out of curiousity is this setup like the one used by skywalker(homebrew amatuer not the cb one) which is one I have posted before?
If the answer to the question about the design is yes did you try the same design with matched transistors and only one bias supply? I figure you could do so the only issues is if they are not matched.
Again nice work very clean.
B
BOOTY MONSTER
Guest
very clean bob85 . are you gonna use that with a very low output radio ? just wondering cause i was under the impression that 4x2879's didnt need a driver pill for full CLEAN output on most radios . thanks
rr its not mine,
i just helped with ideas for the biasing / not having it look like a ratsnest with wires running here there and everywhere, component values were chosen by calculation/experimentation after he chose the top secret lmfao pass transistors
,
theres a separate bias regulator/pass transistor and thermal tracking for each of the two stages and the drive stage, his first bias job and he did a nice clean job
i remember you posting a circuit a while back but i have never tried it and never seen a skywalker other than the dutch guy taking one that looked a real mess and reworking it,
i have used a common bias supply before but only where no viable alternative was available.
i just helped with ideas for the biasing / not having it look like a ratsnest with wires running here there and everywhere, component values were chosen by calculation/experimentation after he chose the top secret lmfao pass transistors
,theres a separate bias regulator/pass transistor and thermal tracking for each of the two stages and the drive stage, his first bias job and he did a nice clean job
i remember you posting a circuit a while back but i have never tried it and never seen a skywalker other than the dutch guy taking one that looked a real mess and reworking it,
i have used a common bias supply before but only where no viable alternative was available.
That amp looks great. VERY neat. I like the relay so that biasing is active only when keying circuit is activated. My compliments to both you guys.
I was just wondering.... If this has Bias other then class C, then why does it look like it still has wire wrapped ferrites going to ground off the back of the input wideband transformers? Am I missing something here? Or were these pictures taken prior to actually hooking up the bias circuit? I see the circuit for bias, just dont understand why there is still the grounded input transformers...looks like a nice job by the way..
Like Bob said if you look at where the choke goes it is a pad that has a wire from under the board coming up in the center. This wire should run back to the relay's center leg and toggle between the bias supply when biased and ground when not.
Crusher that can be done via a transistor used as a switch as well or via relay as shown.
Dang top secret pass transistors and voltage regulator....
As stated I see the other two bias supplies Bob just didn't visually see one for the driver which are probably using transsitors in a to92 case.
Sorry for babling guys back to observing and learning, one of these days I will know something.
Crusher that can be done via a transistor used as a switch as well or via relay as shown.
Dang top secret pass transistors and voltage regulator....
As stated I see the other two bias supplies Bob just didn't visually see one for the driver which are probably using transsitors in a to92 case.
Sorry for babling guys back to observing and learning, one of these days I will know something.
rr where you looking?,
theres 3 x to220 pass transistors and 3 x to220 regulators 3 x 22turn pots, 3 of everything discounting the relay and keying circuit buffer which is common to all three circuits to ensure the are synchronised and it lowers the chances of one relay coil ever failing dropping bias on any one stage and smoking the combiner resistor or worse, if any pass transistor or reg goes short the whole amp should drop back into class C.
theres 3 x to220 pass transistors and 3 x to220 regulators 3 x 22turn pots, 3 of everything discounting the relay and keying circuit buffer which is common to all three circuits to ensure the are synchronised and it lowers the chances of one relay coil ever failing dropping bias on any one stage and smoking the combiner resistor or worse, if any pass transistor or reg goes short the whole amp should drop back into class C.
I see I made an assumption(we all know what that does) that he was using the 2-to220 transistors and a voltage regulator(to220) per 2 transistor module. The assumption was thinking that the 2 transistors would be used for thermal regulation.
Interesting.
So is he using the transistor on the other side of the voltage regulator for thermal regulation or is it being used as a pass transsitor with a diode?
Thats what I get when I step away from a hobby for a while and use my memory, I let what I think I am seeing get in the way of what I am seeing.
Interesting.
So is he using the transistor on the other side of the voltage regulator for thermal regulation or is it being used as a pass transsitor with a diode?
Thats what I get when I step away from a hobby for a while and use my memory, I let what I think I am seeing get in the way of what I am seeing.
rr, the sensing is right beside the pills each circuit is biasing used with a pass transistor,
i know its hard to see how its working, thats not the reason for doing it how he did its just a byproduct of making a tidy job without having unshielded wires running above the board, more work yep but it looks much nicer too imho
i know its hard to see how its working, thats not the reason for doing it how he did its just a byproduct of making a tidy job without having unshielded wires running above the board, more work yep but it looks much nicer too imho
Hey that looks like my handiwork