Has anyone tried this on here?
Seems like it might work as down/dirty fix.
2 people commented the following.
Seems like it might work as down/dirty fix.
2 people commented the following.
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Texas Star Modulator V-Plus sideband mod??
- Thread starter CB590
- Start date
Adding the standard capacitor setup to the Texas Star keying circuit will stop the relay chatter.
And that's all. Like the man said, this is a Class-C amplifier. Means that your sideband signal will sound like doo-doo. Other Texas Star models have fixed bias, and will amplify a SSB signal just fine.
This one won't.
73
And that's all. Like the man said, this is a Class-C amplifier. Means that your sideband signal will sound like doo-doo. Other Texas Star models have fixed bias, and will amplify a SSB signal just fine.
This one won't.
73
Gatekeeper says he worked out the bias issue. Added a second small relay to shut off the bias in receive mode.
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A driver amp on sideband almost always sounds terrible.
The max drive level that still sounds okay on AM will always be more than your sideband audio quality can tolerate.
SSB is just different from AM.
This is why ham amplifiers come with that "ALC" socket on the back. The radio will nearly always have enough drive power to overdrive the amplifier, flatten your voice peaks and ruin the audio quality. The amplifier's ALC hookup is intended to hold the radio below that level.
Of course the radio has its own internal ALC that holds the radio's final stage below that 'flattopping" level. Doesn't necessarily keep the drive level to an amplifier below the threshold where it slices off your modulation peaks.
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The max drive level that still sounds okay on AM will always be more than your sideband audio quality can tolerate.
SSB is just different from AM.
This is why ham amplifiers come with that "ALC" socket on the back. The radio will nearly always have enough drive power to overdrive the amplifier, flatten your voice peaks and ruin the audio quality. The amplifier's ALC hookup is intended to hold the radio below that level.
Of course the radio has its own internal ALC that holds the radio's final stage below that 'flattopping" level. Doesn't necessarily keep the drive level to an amplifier below the threshold where it slices off your modulation peaks.
73
He said that, but I'm pretty sure all he did was to apply a bias current to the transistor like all other TS amps do. The problem with that is that unless it has been biased in class A where the transistor is on all of the time, it still won't fix the audio problems on SSB because the transistor will be off for part of the cycle.
The TS bias system is designed for a push/pull configuration with 2 transistors, and won't work with 1.
I have had the RM 203 for like 4 years. I don't have the Texas Star. I was just wondering about it.
Not initially. Just thought down the line maybe for like a test.
But I think on SSB and say 30-35W or so peak from my AT-6666 the 4 pill should run great. It was tuned to 48-50w peak on SSB with the RF power knob all the way up on a scope. On lowest I get like 20w PEP on sideband.
I know anything over say 28w pep (For all 4 pills) it goes into saturation per the spec sheet for the pills. (More or less).
Thoughts??
Just thoughts....and zero experience with running an amp like that on SSB. I have absolutely no idea what drive levels it might take.
You might dig up the thread from @Shadetree Mechanic where he was discussing his Magnaforce. That might help give you some idea.
I remember when we lasted talked about this and looking at Carl's videos a couple months back that he was putting an obnoxious amount of drive into the class C version, and I believe I couldn't quite understand what he was doing with the biased amplifier.
I'm very curious to see how you make out with your planned drive levels. I don't think I would assume that 28 watts will put it into saturation, as I don't think that takes into account amplifier design.
For what it's worth, I'm running a radio straight into a DX1600 now....I think around 30 watts drive, and I am happy with it. I run half that (or less) into my DX500.
Oh...and if you ever do decide you want or need to run a driver I would ditch the RF keying in both amps. One RF-key and SSB delay is more than enough pain, two would put me over a cliff...LOL!
Here's the thread I was referring to...not a Magnaforce, but a TNT...I bet it's very similar to your amp:
https://www.worldwidedx.com/threads/x-force-600hd-smoked.249976/
https://www.worldwidedx.com/threads/x-force-600hd-smoked.249976/
This is why the T/S amps as well as many others, for SSB, use their own Pre-amp (single pill) just to offset the problems you will have with the dynamics of one dedicated amp to a particular Class (Class C versus AB), and then attempt to drive another with it - the "interface layer" the output of one, into the input of another - requires so much fiddling and mess - it's easier to buy the all-in-one package and live with it and sell off the excess.
Just go to the CB Tricks site and look up the T/Star like the 500 and 667 variables, they use a different "choke" (READ: Matching) method for coupling 1 to 4 - than to match the 50 ohm output a typical amp needs for one output to couple to another - this affects the drive dynamics to the input of the second stage.
Makes for at least a good thought process when you can't sleep at night - at least when you stare at the ceiling - its' a blank canvas, for your "schematic and layout" nightmare to play out for you...