Collins 32V-3 HF Transmitter NICE!!!
 

On Thu, 26 Jan 2006 19:26:21 -0500, Straydog wrote:



The PEAK ENVELOPE POWER output will be 4 times the unmodulated output.
Re-read the deffinition of PEP which you deleted.

Yeah, I read it. Some of us have heard the rumor that the FCC has lawyers
write its material, not engineers. I wasn't too impressed with that
definition, by the way.

Well then if you don't believe anyone you should go and look it up for
yourself. You will find that same deffinition in the ARRL handbook. Oh
I forgot you don't believe what is in there either. Then try some of
the Collins Radio SSB handbooks. Maybe Art Collins didn't know what he
was talking about either? How about in the IEEE handbook.

Keep in mind when trying to understand PEP that there is no peak power
involved. It is all average power.

Also when calculating side band power and carrier power that is all
average power too. Forget about peak power.

Once you understand how this works then you can work from there to
figure out the rest.

I have eliminated all the other stuff as you seem to be going round
and round only for the sake of arguing and not for understanding.

I would encourage you to go to your local library and look at some of
Terman's books or get his radio handbook from ebay etc. Also the
radiotron designer's handbook is excellent.

73
Gary K4FMX

Collins 32V-3 HF Transmitter NICE!!!
 

On Thu, 26 Jan 2006, Gary Schafer wrote:

On Thu, 26 Jan 2006 19:26:21 -0500, Straydog wrote:



The PEAK ENVELOPE POWER output will be 4 times the unmodulated output.
Re-read the deffinition of PEP which you deleted.

Yeah, I read it. Some of us have heard the rumor that the FCC has lawyers
write its material, not engineers. I wasn't too impressed with that
definition, by the way.

Well then if you don't believe anyone you should go and look it up for
yourself. You will find that same deffinition in the ARRL handbook. Oh
I forgot you don't believe what is in there either. Then try some of
the Collins Radio SSB handbooks. Maybe Art Collins didn't know what he
was talking about either? How about in the IEEE handbook.

Keep in mind when trying to understand PEP that there is no peak power
involved. It is all average power.

Also when calculating side band power and carrier power that is all
average power too. Forget about peak power.

Once you understand how this works then you can work from there to
figure out the rest.

I have eliminated all the other stuff as you seem to be going round
and round only for the sake of arguing and not for understanding.

I'm sorry but how you can write a sentence, above, like "Keep in mind when
trying to understand PEP that there is no peak power involved" when you
use "PEP" and "peak power" in the same sentence and say something that
sounds like "its there but it isn't there."

As I've already said in an earlier post that my problem was the conflict
between characteristic curves for tetrodes and pentodes showing no change
in Ip for large changes in Vp and the real need for Ip to move in
proportion to Vp to get a quadrupling of input power on a modulation peak
over an unmodulated carrier. This only can happen if the screen voltage is
modulated along with plate--which everyone, including me, knows--but no
one pointed out that practically all if not all characteristic curves give
only curves for one fixed typical screen voltage.

I would encourage you to go to your local library and look at some of
Terman's books or get his radio handbook from ebay etc. Also the
radiotron designer's handbook is excellent.

73
Gary K4FMX

Collins 32V-3 HF Transmitter NICE!!!
 

On Thu, 26 Jan 2006 22:45:57 -0500, Straydog wrote:



On Thu, 26 Jan 2006, Gary Schafer wrote:

On Thu, 26 Jan 2006 19:26:21 -0500, Straydog wrote:



The PEAK ENVELOPE POWER output will be 4 times the unmodulated output.
Re-read the deffinition of PEP which you deleted.

Yeah, I read it. Some of us have heard the rumor that the FCC has lawyers
write its material, not engineers. I wasn't too impressed with that
definition, by the way.

Well then if you don't believe anyone you should go and look it up for
yourself. You will find that same deffinition in the ARRL handbook. Oh
I forgot you don't believe what is in there either. Then try some of
the Collins Radio SSB handbooks. Maybe Art Collins didn't know what he
was talking about either? How about in the IEEE handbook.

Keep in mind when trying to understand PEP that there is no peak power
involved. It is all average power.

Also when calculating side band power and carrier power that is all
average power too. Forget about peak power.

Once you understand how this works then you can work from there to
figure out the rest.

I have eliminated all the other stuff as you seem to be going round
and round only for the sake of arguing and not for understanding.

I'm sorry but how you can write a sentence, above, like "Keep in mind when
trying to understand PEP that there is no peak power involved" when you
use "PEP" and "peak power" in the same sentence and say something that
sounds like "its there but it isn't there."

Let me explain: There is peak envelope power and there is peak power.
Peak power is seldom used. Peak power is the instantaneous power at
the very peak of the voltage and current. You will see peak currents
discussed in tube manuals often.

Our 100 watt carrier output transmitter with no modulation is 100
watts average power as we talked about before. The actual peak power
is 200 watts output. (nothing to do with modulation right now) This is
found by multiplying the 70.7 volts RMS output voltage by 1.414 to
find peak voltage. That gives us 100 volts peak. Divide that by 50
ohms and we have 200 watts peak output power. Note that peak power is
2x average power with a sin wave.

PEP
Peak envelope power does NOT involve peak power as above. It only
deals with AVERAGE power.
Remember the definition of PEP: The AVERAGE power out at the crest of
the modulation waveform.
(perhaps the "peak" in peak envelope power is a misnomer)

The modulation voltages, that we use to calculate PEP, in each side
band are also RMS voltages, they are not peak voltages.
In the figures below are typical voltages present in the signals at
the output of an AM transmitter modulated 100%. I gave these same
figures in another post.

100 watts into 50 ohms = 70.7 volts (carrier)
25 watts into 50 ohms = 35.35 volts (side band)
25 watts into 50 ohms = 35.35 volts (side band)
Total voltage = 141.4 volts (which is 2 x carrier
voltage)

141.4 x 141.4 = 20000 / 50 = 400 watts PEP. This takes care of our
PEP power.

The amount of voltage that you see on a scope when looking at this
same modulated signal, if we actually measure them with the scope,
will be peak to peak voltage as that is what the scope sees.

So measuring the composite signal voltage on the scope it will show
400 volts peak to peak. Take ½ that to find peak voltage and you have
200 volts peak. To find RMS voltage multiply that by .707 and that
will give you 141.4 RMS volts. This is what is used to calculate PEP.

73
Gary K4FMX

Collins 32V-3 HF Transmitter NICE!!!
 

On Fri, 27 Jan 2006, Gary Schafer wrote:

On Thu, 26 Jan 2006 22:45:57 -0500, Straydog wrote:



On Thu, 26 Jan 2006, Gary Schafer wrote:

On Thu, 26 Jan 2006 19:26:21 -0500, Straydog wrote:



The PEAK ENVELOPE POWER output will be 4 times the unmodulated output.
Re-read the deffinition of PEP which you deleted.

Yeah, I read it. Some of us have heard the rumor that the FCC has lawyers
write its material, not engineers. I wasn't too impressed with that
definition, by the way.

Well then if you don't believe anyone you should go and look it up for
yourself. You will find that same deffinition in the ARRL handbook. Oh
I forgot you don't believe what is in there either. Then try some of
the Collins Radio SSB handbooks. Maybe Art Collins didn't know what he
was talking about either? How about in the IEEE handbook.

Keep in mind when trying to understand PEP that there is no peak power
involved. It is all average power.

Also when calculating side band power and carrier power that is all
average power too. Forget about peak power.

Once you understand how this works then you can work from there to
figure out the rest.

I have eliminated all the other stuff as you seem to be going round
and round only for the sake of arguing and not for understanding.

I'm sorry but how you can write a sentence, above, like "Keep in mind when
trying to understand PEP that there is no peak power involved" when you
use "PEP" and "peak power" in the same sentence and say something that
sounds like "its there but it isn't there."

Let me explain: There is peak envelope power and there is peak power.
Peak power is seldom used. Peak power is the instantaneous power at
the very peak of the voltage and current. You will see peak currents
discussed in tube manuals often.

Yes, and I've looked at them very often. The term "instantaneous power"
seems more appropriate to me since it implies a time dependent function,
but that is just my prefernce. More below.

Our 100 watt carrier output transmitter with no modulation is 100
watts average power as we talked about before. The actual peak power
is 200 watts output. (nothing to do with modulation right now) This is
found by multiplying the 70.7 volts RMS output voltage by 1.414 to
find peak voltage. That gives us 100 volts peak. Divide that by 50
ohms and we have 200 watts peak output power. Note that peak power is
2x average power with a sin wave.

PEP
Peak envelope power does NOT involve peak power as above. It only
deals with AVERAGE power.
Remember the definition of PEP: The AVERAGE power out at the crest of
the modulation waveform.
(perhaps the "peak" in peak envelope power is a misnomer)

I think it very well is a misnomer, but that is also maybe "my" problem.
Defining what we mean, and explaining very technical issues bery
accurately is much more difficult than most people realize and sometimes
people read things and still don't understand what they are reading. Just
about everything you wrote above and below is fine with me except that
I've already explained several times in several posts that the problem I
always had, for tetrodes and above, is that all the published curves show
Ip being independent of Vp and I could not see how, under modulation,
there would be enough instantaneous input power to give a 4X instataneous
output instantaneous power. Now that I realize that modulating screen
voltage can make Ip move in proportion to Vp, and thus give double current
at double voltage, my problem with understanding this dissapears. And,
this was the major basis for my squabble with the PEP spec on the 32V3
original post. Non linearities are still an issue, but minor. I guess I am
just dismayed that nobody is reading what I'm saying to see what I'm
saying but they all jump in to talk about everything except the problem
that I more or less figured out by myself after re-reading, thinking, and
getting some stimulation from the discussions.

But, thank you for your time. You need not repeat yourself any more.

===== no change to below, included for reference and context =====

The modulation voltages, that we use to calculate PEP, in each side
band are also RMS voltages, they are not peak voltages.
In the figures below are typical voltages present in the signals at
the output of an AM transmitter modulated 100%. I gave these same
figures in another post.

100 watts into 50 ohms = 70.7 volts (carrier)
25 watts into 50 ohms = 35.35 volts (side band)
25 watts into 50 ohms = 35.35 volts (side band)
Total voltage = 141.4 volts (which is 2 x carrier
voltage)

141.4 x 141.4 = 20000 / 50 = 400 watts PEP. This takes care of our
PEP power.

The amount of voltage that you see on a scope when looking at this
same modulated signal, if we actually measure them with the scope,
will be peak to peak voltage as that is what the scope sees.

So measuring the composite signal voltage on the scope it will show
400 volts peak to peak. Take ½ that to find peak voltage and you have
200 volts peak. To find RMS voltage multiply that by .707 and that
will give you 141.4 RMS volts. This is what is used to calculate PEP.

73
Gary K4FMX

Collins 32V-3 HF Transmitter NICE!!!
 

Don ... you are correct!
73, Lee ZL2AL (Old AMer of the 50s)

"Don Bowey" wrote in message
...
On 1/24/06 12:57 PM, in article 6xwBf.11951$bF.2404@dukeread07, "Uncle
Peter" wrote:


"Straydog" wrote in message
My understanding of AM transmitter technology would estimate that a
32v3,
with ~120 DC input (two 6146s, or were they still using one 4D32?)
would
have at most (class C, plate modulated) 70% X 120 = 80 watts of CW
carrier
output. 60 watts of audio on that final tube (as a non-linear high
level
mixer) will at best, double the _instantaneous_ (peak) input voltage,
therefore power to 240 watts (plate current will _not_ double even if
the
plate voltage doubles on peak audio cycle [look at your tube curves
again
of iP vs vP at constant biases]) which you could only attempt to
measure
with an oscilloscope. Peak output? Could it be more than 240 x 0.7 =
168
watts? I doubt it (unless he's got something like "super-modulation" in
the rig).


Without delving into the limitations of the 32V3, according to the info
from an ARRL publication:

"..since the amplitude at the peak of the upswing is twice the
unmodulated
amplitude, the power at this instant is four times the unmodulated, or
400
watts."

Average power, on the other hand, will be 1.5 times carrier. A Class C
amplifier with high level modulation should produce an instaneous PEP
of 4x carrier power.

Pete






Getting back to basics: A 120W (input) power, class C stage, will require
60W of audio (using a high-level, e.g. plate, modulator) for 100%
modulation. If we assume 85% efficiency, then the output will consist of
a
Carrier of 102W and two sidebands of 25.5W each.

In my opinion, any other explanation is useless. Do remember that the
carrier amplitude does NOT vary with modulation.

Don

Collins 32V-3 HF Transmitter NICE!!!
 

Don ... you are correct!
73, Lee ZL2AL (Old AMer of the 50s)


Getting back to basics: A 120W (input) power, class C stage, will
require
60W of audio (using a high-level, e.g. plate, modulator) for 100%
modulation. If we assume 85% efficiency, then the output will consist
of
a
Carrier of 102W and two sidebands of 25.5W each.

In my opinion, any other explanation is useless. Do remember that the
carrier amplitude does NOT vary with modulation.

Don

Wohoooo here, maybe, since I caught this thread in mid stream, I am out
of place, but Don, your last sentence, "Do remember that the carrier
amplitude does NOT vary with modulation." doesn't sound like high level
amplitude modulation.

When I was young(er), amplitude modulation meant exactly that: carrier
amplitude varying with modulation. In fact, when working out the bugs of
home designed and built AM transmitters, one favorite test was with an
oscilloscope, measuring the amplitude of the carrier, making sure that the
carrier amplitude did actually approach zero and rise to twice the
unmodulated carrier level. (voltage, not power, of course)

Now, for sure, the carrier average POWER didn't vary (much), but the
audio power was added. Now, PEP, peak envelope power, is a whole different
thing for us old timers, and maybe that's what is being discussed here. In
that case, please excuse Mr. Buttinski!

Old Chief Lynn, W7LTQ

Collins 32V-3 HF Transmitter NICE!!!
 

Hi, Lynn

The oscilloscope monitor on an A.M. transmitter output
doesn't show the carrier (except during periods
of no modulation). The scope shows the resultant
of the carrier and both sidebands added together vectorially.
A spectrum analyzer would show a constant amplitude carrier
in the center of the A.M. spectrum.

There is a good description of the process at the Agilent site.
Google a.m. phasor diagram
Click on "Spectrum analysis AM and FM HP T&M Application Note 150-1"
Beginning on page 48 of the pdf file is a description of the a.m.
spectrum, based on phasor diagrams.

73,
Ed Knobloch

Lynn Coffelt wrote:
Wohoooo here, maybe, since I caught this thread in mid stream, I am out
of place, but Don, your last sentence, "Do remember that the carrier
amplitude does NOT vary with modulation." doesn't sound like high level
amplitude modulation.

When I was young(er), amplitude modulation meant exactly that: carrier
amplitude varying with modulation. In fact, when working out the bugs of
home designed and built AM transmitters, one favorite test was with an
oscilloscope, measuring the amplitude of the carrier, making sure that the
carrier amplitude did actually approach zero and rise to twice the
unmodulated carrier level. (voltage, not power, of course)

Now, for sure, the carrier average POWER didn't vary (much), but the
audio power was added. Now, PEP, peak envelope power, is a whole different
thing for us old timers, and maybe that's what is being discussed here. In
that case, please excuse Mr. Buttinski!

Old Chief Lynn, W7LTQ