To make it transmit with a constant carrier level, regardless of the modulation applied.
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Using Magnum S-9 with a linear amplifier ?
- Thread starter Pilsener
- Start date
To make it transmit with a constant carrier level, regardless of the modulation applied.
I don't think you get what I mean......
Back in the days when I was even younger than now, I had an AM transmitter that was rated as 5 watts. No matter if I screamed into the mic, or didn't say a word, it still put out 5 watts. The ppl I talked to got a steady reading of me on their S-meters.
Back in the days when I was even younger than now, I had an AM transmitter that was rated as 5 watts. No matter if I screamed into the mic, or didn't say a word, it still put out 5 watts. The ppl I talked to got a steady reading of me on their S-meters.
you had problems back then too. by definition an am transmitter produces more power output when the transmitter is modulated regardless as to whether average or pep measurements are used.
the average power increase produced by a PROPERLY MODULATED AM TRANSMITTER (100%) is 1.76db., or 1.5 times the resting, unmodulated carrier.
the peak envelope power produced by a PROPERLY MODULATED AM TRANSMITTER (100%) is 6db., or 4.0 times the resting, unmodulated carrier.
the same confusion still exists today when cb radios are referred to as producing 4W of power output. they do produce 4W OF CARRIER & anywhere from 5.5-6.5W of average power or 12-18W of peak envelope power AS INDEED THEY SHOULD WHEN THE TRANSMITTER IS MODULATED at levels just at or under 100%, Modulation Index = 1.
the only transmitter mode that most of us are familiar with that does not produce additional power under modulation is FM.
if you were indeed using an AM TRANSMITTER then something was seriously wrong. either the measuring equipment was defective, the transmitter was operating in FM Mode or the transmitter was improperly tuned / aligned.
take your pick.
http://www.firecommunications.com/hlsos.html
the average power increase produced by a PROPERLY MODULATED AM TRANSMITTER (100%) is 1.76db., or 1.5 times the resting, unmodulated carrier.
the peak envelope power produced by a PROPERLY MODULATED AM TRANSMITTER (100%) is 6db., or 4.0 times the resting, unmodulated carrier.
the same confusion still exists today when cb radios are referred to as producing 4W of power output. they do produce 4W OF CARRIER & anywhere from 5.5-6.5W of average power or 12-18W of peak envelope power AS INDEED THEY SHOULD WHEN THE TRANSMITTER IS MODULATED at levels just at or under 100%, Modulation Index = 1.
the only transmitter mode that most of us are familiar with that does not produce additional power under modulation is FM.
if you were indeed using an AM TRANSMITTER then something was seriously wrong. either the measuring equipment was defective, the transmitter was operating in FM Mode or the transmitter was improperly tuned / aligned.
take your pick.
http://www.firecommunications.com/hlsos.html
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Well...AM is not the most important thing here in Norway. Hardly anyone use it anymore.
SSB is more interesting.
Any neat tricks to keep the S-9 below 20 W on SSB ?
The Zetagi amp has a 6 step output power switch. And as far as I can see on the schematics, it's possible that setting this switch to a low setting will reduce the signal into the output stage, thus preventing it from blowing.
Will this do ?
SSB is more interesting.
Any neat tricks to keep the S-9 below 20 W on SSB ?
The Zetagi amp has a 6 step output power switch. And as far as I can see on the schematics, it's possible that setting this switch to a low setting will reduce the signal into the output stage, thus preventing it from blowing.
Will this do ?
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there are no tricks and like i said in a previous thread no modifications are required. if that POS Zetagi has multiple power levels then use the lower ones and take advantage of the input padding afforded.
or,
add a 3-6db. pad rated for the power developed at the output of the transmitter.
or,
have the S9 matched to the input of the amplifier by a qualified service technician.
or,
add a 3-6db. pad rated for the power developed at the output of the transmitter.
or,
have the S9 matched to the input of the amplifier by a qualified service technician.
Pilsner - the problem is that you have a radio and Amp that really shouldn't be run together.
Can you make an S9 do less than 20 watts on SSB? YES, but it goes against all properties of what that radio was meant to do.
You can't put a V8 engine inside a toyota tercel. Maybe you could with a ton of modifications, but by the time you do all the mods what the hell was the point in buying the V8 engine?
The radio needs an 2 x 2290 or 2 x 2879 or even a straight 4 x 1446 amplifier.
I've run exports doing 30 watts SSB into a 2 x 1446 without problems, but you have to know what the amp can handle and what your radio is doing for output.
The Magnum S-9 is a great radio - what is the point in detuning a great radio to run with that amplifier?
If you want to get the full worth of that radio buy a proper amplifier to match up with it.
Otherwise buy a SSB single final radio that only does 12 watts SSB that will match up with that amplifier if you insist on using it.
Can you make an S9 do less than 20 watts on SSB? YES, but it goes against all properties of what that radio was meant to do.
You can't put a V8 engine inside a toyota tercel. Maybe you could with a ton of modifications, but by the time you do all the mods what the hell was the point in buying the V8 engine?
The radio needs an 2 x 2290 or 2 x 2879 or even a straight 4 x 1446 amplifier.
I've run exports doing 30 watts SSB into a 2 x 1446 without problems, but you have to know what the amp can handle and what your radio is doing for output.
The Magnum S-9 is a great radio - what is the point in detuning a great radio to run with that amplifier?
If you want to get the full worth of that radio buy a proper amplifier to match up with it.
Otherwise buy a SSB single final radio that only does 12 watts SSB that will match up with that amplifier if you insist on using it.
"Can you make an S9 do less than 20 watts on SSB? YES, but it goes against all properties of what that radio was meant to do."
right. that's why it's equipped with a variable rf power output control. where's the "laughing my ass off" icon at when i need it?
:laugh:
right. that's why it's equipped with a variable rf power output control. where's the "laughing my ass off" icon at when i need it?
:laugh:
I was asking all these questions because I didn't want to detune the S-9, but I was hoping that I still could run this amp without blowing anything. I also didn't want to invent the wheel all over again, so I thought it was better to ask someone who maybe had done this combo before.
I love this S-9, so I wanted to do as little fiddling as possible.
But what do you guys think about using a Cobra 200 GTL instead ?
Sure it's a radio with a ...... ehmm.....questionable reputation, but it's rated 4 W on AM/FM and 12 W SSB in the low-power mode.
Would this fit this amp better ?
I love this S-9, so I wanted to do as little fiddling as possible.
But what do you guys think about using a Cobra 200 GTL instead ?
Sure it's a radio with a ...... ehmm.....questionable reputation, but it's rated 4 W on AM/FM and 12 W SSB in the low-power mode.
Would this fit this amp better ?
properly adjusting the OUTPUT of the S9 HAS NOTHING TO DO WITH "TUNING".
"4 W on AM/FM and 12 W SSB in the low-power mode."
4W of what? how much power is generated in AM mode when the transmitter is modulated?
"4 W on AM/FM and 12 W SSB in the low-power mode."
4W of what? how much power is generated in AM mode when the transmitter is modulated?
No, a Cobra 200GTL would fry that amp quicker than a S9.
If you absolutely must run that amp you need a "single final output radio" such as a typical CB uses. Or a dual final radio that doesn't do a whole lot on output.
freecell made an excellent point - you can tune down the variable on that radio so the deadkey is within reason for that amp - the problem is the swing...the swing on that radio doesn't really decrease with rf power knob, you have to detune the radio for lower swing numbers. Magnums are built to deadkey 1 watt and swing 40.
On SSB the RF gain knob can decrease the SSB swing - been awhile since I had one in front of me - but if I remember correctly the RF knob doesn't effect the SSB power output a whole lot.
If you absolutely must run that amp you need a "single final output radio" such as a typical CB uses. Or a dual final radio that doesn't do a whole lot on output.
freecell made an excellent point - you can tune down the variable on that radio so the deadkey is within reason for that amp - the problem is the swing...the swing on that radio doesn't really decrease with rf power knob, you have to detune the radio for lower swing numbers. Magnums are built to deadkey 1 watt and swing 40.
On SSB the RF gain knob can decrease the SSB swing - been awhile since I had one in front of me - but if I remember correctly the RF knob doesn't effect the SSB power output a whole lot.
"the swing on that radio doesn't really decrease with rf power knob, you have to detune the radio for lower swing numbers."
wrong again. that's what the AMC (AM) and ALC (SSB) adjustments are for.
wrong again. that's what the AMC (AM) and ALC (SSB) adjustments are for.
by designing a series-parallel resistor network approximating a pure 50 ohm impedance that reduces any input by 3 - 6 db. at the output side while safely dissipating the power lost as a result of the network attenuation without excessive heating of the resistors used to design the network.
it's a lot easier to just reduce the transmitter output by 3 - 6 db.. and this is not an extreme case by any means as i can do the same thing using transmitters like the CX4300HP (into the same 2XSD1446 transistor complement) which produces much more power output than the S9.
it's a lot easier to just reduce the transmitter output by 3 - 6 db.. and this is not an extreme case by any means as i can do the same thing using transmitters like the CX4300HP (into the same 2XSD1446 transistor complement) which produces much more power output than the S9.
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He understands everthing you're saying but he'll just keep thumping you on your nutsack as long as you alow him to.
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