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Data mode and filters

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Jim Brown-10

Re: Data mode and filters

Joe,

Your logic is still faulty.

For my measurements, I set the K3 for 100W, recorded the power measured
by the LP-100A, which we both agree can miss some peaks, SO according to
your logic, I WAS overdriving the K3. Yet, the measured bandwidth is
quite narrow.

On Sun,5/17/2015 6:38 AM, Joe Subich, W4TV wrote:

>
> > No, but they/we can put a calibrated peak-reading wattmeter like the
> > LP-100A in line with the feed to our antennas.
>
> While a peak reading wattmeter like the LPA-100 is a good step, it
> still does not respond to instantaneous peaks. Most "peak reading"
> wattmeters will show peak values that vary depending on the PSK31
> datastream and never show the true instantaneous peak.
>
> > And last I looked, few hams run much power with PSK-31.
>
> They have to do that or they would be clipping terribly in the final
> amplifier stage (or in the transmit IF of some poorly aligned rigs).
> They certainly can't push the rigs to 100W as your tests would imply.

My measurements clearly show what a K3 does when set to 100W.

73, Jim K9YC

>
> 73,
>
> ... Joe, W4TV
>
>
> On 2015-05-15 12:44 PM, Jim Brown wrote:
>> On Fri,5/15/2015 9:10 AM, Joe Subich, W4TV wrote:
>>> The vast majority of amateurs do not have calibrated scopes on the
>>> output of their transmitter/amplifier to keep the instantaneous peak
>>> output below the onset of compression in the final stage of power
>>> amplification.
>>
>> No, but they/we can put a calibrated peak-reading wattmeter like the
>> LP-100A in line with the feed to our antennas.
>>
>> And last I looked, few hams run much power with PSK-31. As both my
>> measurements and K6XX measurements clearly show, IMD in the K3 drops
>> significantly below full power.
>>
>> 73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

> For my measurements, I set the K3 for 100W, recorded the power
> measured by the LP-100A, which we both agree can miss some peaks, SO
> according to your logic, I WAS overdriving the K3.

Yes, you were probably over driving the K3 (KPA3). You can estimate
the amount of overdrive by using the the LP-100A Peak to Average
function. With PSK31 "idle", the LP-100A shows the following:

K3 Power setting CW Power Peak Average Peak to average
20W 20.6W 19.5W 7.5W 4.2 dB
30W 31.4W 29.8W 11.8W 4.0 dB
40W 40.2W 39.2W 15.7W 3.9 dB
50W 50.2W 49.1W 19.8W 3.9 dB
60W 57.7W 58.4W 24.0W 3.8 dB
70W 66.8W 66.2W 28.7W 3.6 dB
80W 75.0W 75.9W 33.1W 3.6 dB
90W 84.6W 83.7W 38.2W 3.4 dB
100W 97.0W 93.3W 43.6W 3.3 dB
110W 103.0W 102.4W 50.2W 3.0 dB

The "CW" power is an unmodulated PSK31 subcarrier. Peak and Average
are measured by the LP-100A. Note that the Peak to Average only drops
1 dB from 20W to 100W (1dB compression) for the PSK31 idle and the
average power stays below 50W so while you are over driving the KPA3,
you're not seriously over driving at the 100W (peak) level with PSK.
At least with a stiff 13.8V supply the KPA3 does not seem to reach
1 dB compression until almost 100W (peak) output.

In addition, with PSK31 the 3rd order products are only +/- 45 Hz
from the "carrier", the fifth only +/- 77 Hz, seventh only +/- 108
Hz, etc. - you are not going to measure a lot of width until the
distortion is bad enough to generate really high order products.

Don't try this with the ALC systems in some other rigs - the excess
gain in their IF stages will make a mess well before 100W peak out.

73,

... Joe, W4TV

On 2015-05-17 12:36 PM, Jim Brown wrote:

> Joe,
>
> Your logic is still faulty.
>
> For my measurements, I set the K3 for 100W, recorded the power measured
> by the LP-100A, which we both agree can miss some peaks, SO according to
> your logic, I WAS overdriving the K3. Yet, the measured bandwidth is
> quite narrow.
>
> On Sun,5/17/2015 6:38 AM, Joe Subich, W4TV wrote:
>>
>> > No, but they/we can put a calibrated peak-reading wattmeter like the
>> > LP-100A in line with the feed to our antennas.
>>
>> While a peak reading wattmeter like the LPA-100 is a good step, it
>> still does not respond to instantaneous peaks. Most "peak reading"
>> wattmeters will show peak values that vary depending on the PSK31
>> datastream and never show the true instantaneous peak.
>>
>> > And last I looked, few hams run much power with PSK-31.
>>
>> They have to do that or they would be clipping terribly in the final
>> amplifier stage (or in the transmit IF of some poorly aligned rigs).
>> They certainly can't push the rigs to 100W as your tests would imply.
>
> My measurements clearly show what a K3 does when set to 100W.
>
> 73, Jim K9YC
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2015-05-15 12:44 PM, Jim Brown wrote:
>>> On Fri,5/15/2015 9:10 AM, Joe Subich, W4TV wrote:
>>>> The vast majority of amateurs do not have calibrated scopes on the
>>>> output of their transmitter/amplifier to keep the instantaneous peak
>>>> output below the onset of compression in the final stage of power
>>>> amplification.
>>>
>>> No, but they/we can put a calibrated peak-reading wattmeter like the
>>> LP-100A in line with the feed to our antennas.
>>>
>>> And last I looked, few hams run much power with PSK-31. As both my
>>> measurements and K6XX measurements clearly show, IMD in the K3 drops
>>> significantly below full power.
>>>
>>> 73, Jim K9YC
>
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>

Jim Brown-10

Re: Data mode and filters

On Sun,5/17/2015 7:29 PM, Joe Subich, W4TV wrote:
> Yes, you were probably over driving the K3 (KPA3). You can estimate
> the amount of overdrive by using the the LP-100A Peak to Average
> function. With PSK31 "idle", the LP-100A shows the following:

Perhaps, BUT -- look at the data for 100W, 93W, 50W. and 29W. The 100W
and 93W data clearly shows IMD at levels corresponding to 2-tone data,
the difference between 100W and 93W is 4 dB, and at 50W almost no IMD is
visible (there are sidebands +/- 360 Hz 60 dB down). 50W gets a legal
limit amp to full power. At 30W, which gets the KPA500 to full power,
sidebands at about +/- 50 Hz are barely visible, there are -63 dBc
sidebands at about +/- 360 Hz.

But let's return to the real world issue -- QRM as the result of
excessive occupied bandwidth. The K3 I measured is 105 Hz wide at -40
dBC at 29W, 110 Hz at 50W. At -60 dBC, it's 340 Hz at 29W and 720 Hz at
50W.

Given that the vast majority of PSK31 ops work below 50W and that 50W to
a power amp will get you to 1500W, your concerns simply do not make
sense in the real world.

73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

> 50W gets a legal limit amp to full power.

Only with some solid state a and ceramic tube amplifiers. Many of
the glass tube amplifiers need every one of the 100Wto reach 1500W
PEP output.

> Given that the vast majority of PSK31 ops work below 50W and that 50W
> to a power amp will get you to 1500W, your concerns simply do not
> make sense in the real world.

You are extrapolating the behavior of the K3 with its open loop ALC
and reasonably behaved KPA3 to other rigs. The results would be
very different if you were pushing a "12V" Icom, Kenwood, or Yaesu
rig. All of this still requires the user understand the concept
of "crest factor" and use a wattmeter that properly indicates peak
power.

73,

... Joe, W4TV

On 2015-05-18 3:26 AM, Jim Brown wrote:

> On Sun,5/17/2015 7:29 PM, Joe Subich, W4TV wrote:
>> Yes, you were probably over driving the K3 (KPA3). You can estimate
>> the amount of overdrive by using the the LP-100A Peak to Average
>> function. With PSK31 "idle", the LP-100A shows the following:
>
> Perhaps, BUT -- look at the data for 100W, 93W, 50W. and 29W. The 100W
> and 93W data clearly shows IMD at levels corresponding to 2-tone data,
> the difference between 100W and 93W is 4 dB, and at 50W almost no IMD is
> visible (there are sidebands +/- 360 Hz 60 dB down). 50W gets a legal
> limit amp to full power. At 30W, which gets the KPA500 to full power,
> sidebands at about +/- 50 Hz are barely visible, there are -63 dBc
> sidebands at about +/- 360 Hz.
>
> But let's return to the real world issue -- QRM as the result of
> excessive occupied bandwidth. The K3 I measured is 105 Hz wide at -40
> dBC at 29W, 110 Hz at 50W. At -60 dBC, it's 340 Hz at 29W and 720 Hz at
> 50W.
>
> Given that the vast majority of PSK31 ops work below 50W and that 50W to
> a power amp will get you to 1500W, your concerns simply do not make
> sense in the real world.
>
> 73, Jim K9YC
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Message delivered to [hidden email]
>

Jim Brown-10

Re: Data mode and filters

On Mon,5/18/2015 5:40 AM, Joe Subich, W4TV wrote:
> You are extrapolating the behavior of the K3 with its open loop ALC
> and reasonably behaved KPA3 to other rigs. The results would be
> very different if you were pushing a "12V" Icom, Kenwood, or Yaesu
> rig.

No, I'm talking about a K3, which is what I measured. The two Yaesu rigs
I've measured, both run only on 120/240VAC, and their IMD and occupied
spectrum do NOT decrease with power level.

You are clearly on a mission to shift the ham world to high voltage PAs.
But a significant part of the ham world wants a radio that runs on
11-14VDC, making it much more versatile for portable and mobile
operation, carry-on in luggage for a DX trip, and easy to run from a
simple solar power system.

73, Jim K9YC
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Joe Subich, W4TV-4

Re: Data mode and filters

> You are clearly on a mission to shift the ham world to high voltage
> PAs.

No, I'm on a mission - if that's what you call it - to get the ham
world to stop using devices with output impedance below 2 Ohms. Most
times those are coupled with 16:1 broadband transformers and one gets
significant peak non-linearity because of impedance mismatch and/or
core saturation problems.

If you want to use 12V systems, use multiple amplifiers in parallel
or use a lower power output. If you want higher power with only a
single pair of devices, get the voltage/impedance up where they will
operate properly.

> But a significant part of the ham world wants a radio that runs on
> 11-14VDC, making it much more versatile for portable and mobile
> operation, carry-on in luggage for a DX trip, and easy to run from a
> simple solar power system.

There is nothing sacred about 11-14V for any of those functions.
Simple solar and battery power systems can handle higher voltages -
it's just a matter of design and planning, switching supplies for DX
trips can be made just as physically small in higher/multiple voltages
(particularly since they typically need to handle less than half the
current, and quiet "boost regulators" solve the mobile issue.

12V is only used because it has always been used. Modern equipment
designers make too many compromises in signal quality to force 12V
operation. "Boost Regulators" (e.g. vibrator or motor generator
supplies) were used for high voltage PAs even in the *tube* days.

73,

... Joe, W4TV

On 2015-05-18 12:36 PM, Jim Brown wrote:

> On Mon,5/18/2015 5:40 AM, Joe Subich, W4TV wrote:
>> You are extrapolating the behavior of the K3 with its open loop ALC
>> and reasonably behaved KPA3 to other rigs. The results would be
>> very different if you were pushing a "12V" Icom, Kenwood, or Yaesu
>> rig.
>
> No, I'm talking about a K3, which is what I measured. The two Yaesu rigs
> I've measured, both run only on 120/240VAC, and their IMD and occupied
> spectrum do NOT decrease with power level.
>
> You are clearly on a mission to shift the ham world to high voltage PAs.
> But a significant part of the ham world wants a radio that runs on
> 11-14VDC, making it much more versatile for portable and mobile
> operation, carry-on in luggage for a DX trip, and easy to run from a
> simple solar power system.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Wes (N7WS)

Re: Data mode and filters

Ahem.

I've said before that I used a floating battery and boost regulator to keep the
supply voltage at the high end of the spec. (I have a KPA500 inline now, so this
has changed somewhat.)

But I've seen comments here more than once that someone's K3 "works" down to 11
V. or some such number.

I'm hoping that Elecraft has a PIP that will add another connector to the KPA3A
to run it on 28-50V to make a K3S/200+.

Wes N7WS

On 5/18/2015 12:48 PM, Joe Subich, W4TV wrote:

>
> No, I'm on a mission - if that's what you call it - to get the ham
> world to stop using devices with output impedance below 2 Ohms. Most
> times those are coupled with 16:1 broadband transformers and one gets
> significant peak non-linearity because of impedance mismatch and/or
> core saturation problems.
>
> If you want to use 12V systems, use multiple amplifiers in parallel
> or use a lower power output. If you want higher power with only a
> single pair of devices, get the voltage/impedance up where they will
> operate properly.
>
> > But a significant part of the ham world wants a radio that runs on
> > 11-14VDC, making it much more versatile for portable and mobile
> > operation, carry-on in luggage for a DX trip, and easy to run from a
> > simple solar power system.
>
> There is nothing sacred about 11-14V for any of those functions.
> Simple solar and battery power systems can handle higher voltages -
> it's just a matter of design and planning, switching supplies for DX
> trips can be made just as physically small in higher/multiple voltages
> (particularly since they typically need to handle less than half the
> current, and quiet "boost regulators" solve the mobile issue.
>
> 12V is only used because it has always been used. Modern equipment
> designers make too many compromises in signal quality to force 12V
> operation. "Boost Regulators" (e.g. vibrator or motor generator
> supplies) were used for high voltage PAs even in the *tube* days.
>
> 73,
>
> ... Joe, W4TV

Jim Brown-10

Re: Data mode and filters

In reply to this post by Joe Subich, W4TV-4

On Mon,5/18/2015 12:48 PM, Joe Subich, W4TV wrote:
> There is nothing sacred about 11-14V for any of those functions.
> Simple solar and battery power systems can handle higher voltages -

AND having to buy equipment to support those higher voltages. Most of us
have vehicles with 13.8V systems, big deep discharge batteries are a
mass market item, and thus inexpensive.

73, Jim K9YC
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Jim Bolit

Re: Data mode and filters

High end car stereo amps use DC/DC's. Yea it's audio, but ya pay to play.
There are 300 watt DC/DC made by Vicor, Belfuse et. al.

Yea, it is more money. But people that want to put a K3 in a mobile is out
at 4 or 5 sigma's (no data, relax, but reasonable estimate)

If ya want mobile, get the KX3. A rig used primarily for base station
operation could be designed for better performance. Business and marine
radios run off 12 volts and have better IMD performance, but the mfg's get
more $ for them, BUT the end sell price is not solely set by their
manufacturing and overhead costs alone.

Jim
W6AIM

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
Brown
Sent: Monday, May 18, 2015 5:29 PM
To: [hidden email]
Subject: Re: [Elecraft] Data mode and filters

On Mon,5/18/2015 12:48 PM, Joe Subich, W4TV wrote:
> There is nothing sacred about 11-14V for any of those functions.
> Simple solar and battery power systems can handle higher voltages -

AND having to buy equipment to support those higher voltages. Most of us
have vehicles with 13.8V systems, big deep discharge batteries are a mass
market item, and thus inexpensive.

73, Jim K9YC
______________________________________________________________
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delivered to [hidden email]

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Bill W4ZV

Re: Data mode and filters

This is more entertaining than the Mayfield-Pacquiao fight!

Who will get the last word?

73, Bill W4ZV

123