subject:"\[Elecraft\] IMD and supply voltage"

[Elecraft] IMD and supply voltage

2015-10-30 Thread Charlie Delta via Elecraft

Hi Wayne

How about these ham transceivers? I pulled the data  from my saved QST reviews 
of these radios that I have owned in the past.
I do recall that they did  have transmitter IMD data that was head and 
shoulders above   what was available when they were released.

This data is from the QST reviews and not my owned measured  data. All these 
radios operated on a 12 volt supply.

FT990  3rd -38  5th -47  
FT767  3rd -40  5th -45
TS450  3rd -35  5th -49
IC737   3rd -39  5th -48

The higher order data from the QST reviews indicated a rapid fall off above the 
5th to the 11th order.
 
Low IMD figures while operating from a 12 volt power supply certainly seems to 
be realizable.

73
Craig



"If you have another marine radio in mind that you think is using 
different/better circuitry, please let me know so we can repeat this exercise 
if necessary.

73,
Wayne
N6KR"

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-30 Thread Charlie T, K3ICH

Yep, I remember a certain net control op claiming
to put his rig into "war" mode during a weekly
Sunday net when competing with the incessant
"seeque keyontest" encroachment.

He was running a grid driven 4CX-1000A .  All he
had to do was drive it so a few milliamps of grid
current showed and like magic, the frequency was
clear.

This was the "street-sweeper"  * of radio set-ups
and pretty guaranteed  a QRM free frequency for
the net.

Not sayin' I condone such antics, but it WAS
effective.

73, Charlie k3ICH



 * Street-Sweeper, a rotary magazine 12 shot, 12
Ga semi-automatic shotgun.  Sorta looks like fat
version of the popular Thompson machine gun.





Yes, I understand completely.  From a "Real World
Practical" standpoint, if I have a really clean
transmitter with lovely IMD specifications and I
stuff over compressed, highly processed, all
compressor-limiter knobs to the right audio into
it I will get completely unintelligible audio with
wonderful technical specifications and still
bother my neighbors.

And don't forget. Some contesters *WANT* the
scenario you described above.
No sense in sweeping that under the rug!


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-30 Thread Eric Swartz - WA6HHQ, Elecraft

This thread is now closed. We're drifting way off topic.(We asked that it be 
would down last night.)


73,

Eric
/elecraft.com/

On 10/30/2015 7:19 AM, Jim Bolit wrote:

NO!! Us Californian's understand dB. If you ain't increasing power in 10 dB 
increments, don't bother.
Eimac made 4CX1's based on market demand in California.
Don't ask me how I know this...
JimW6AIM




__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-30 Thread Merv Schweigert


Several years back I had obtained some excellent 4cx5 and
4cx10k tubes,   they were a little more juice than my house
mains power could handle,  so I sold them  ..  the pair of
4cx10k went to a ham in CA who was "upgrading" his amp
that used a pair of 4cx5K at the time,  easy upgrade since the
sockets are the same etc.
There were several 4cx10K amps in the St Louis area at that time
so its not just a CA option.
THis was before Elecraft..  so OT I suspect.
73 Merv K9FD/KH6

NO!! Us Californian's understand dB. If you ain't increasing power in 10 dB 
increments, don't bother.
Eimac made 4CX1's based on market demand in California.
Don't ask me how I know this...
JimW6AIM

.

 Original message 
From: Vic Rosenthal 
Date: 10/29/2015  10:50 PM  (GMT-08:00)
To: Elecraft Reflector 
Subject: Re: [Elecraft] IMD and supply voltage

As I think I remember, in California the limit was 1500 watts, unless you were 
calling an ATNO (all-time new one) in which case it was 5 kW.

Vic 4X6GP/K2VCO


On 30 Oct 2015, at 12:55 AM, Doug Turnbull  wrote:

Of course this is a comparison of these two amps.   Please note that
1500 Watts is only used for contests which we are allowed to use for some
contests in EI but not for regular operating where our power limit is 400W
output.

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jbol...@outlook.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to k...@flex.com



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-30 Thread Jim Bolit

NO!! Us Californian's understand dB. If you ain't increasing power in 10 dB 
increments, don't bother.
Eimac made 4CX1's based on market demand in California.
Don't ask me how I know this...
JimW6AIM

.

 Original message 
From: Vic Rosenthal 
Date: 10/29/2015  10:50 PM  (GMT-08:00)
To: Elecraft Reflector 
Subject: Re: [Elecraft] IMD and supply voltage

As I think I remember, in California the limit was 1500 watts, unless you were 
calling an ATNO (all-time new one) in which case it was 5 kW.

Vic 4X6GP/K2VCO

> On 30 Oct 2015, at 12:55 AM, Doug Turnbull  wrote:
>
> Of course this is a comparison of these two amps.   Please note that
> 1500 Watts is only used for contests which we are allowed to use for some
> contests in EI but not for regular operating where our power limit is 400W
> output.
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jbol...@outlook.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-30 Thread Luis V. Romero

Joe and all:

>
>Comparing processing issues and transmitter IMD are mixing apple and
>oranges.  Processing issues generally affect the quality of signal
>*on channel* - the ability to understand the audio - whilst IMD is the
>"off frequency" splatter up/down the band that interferes with everyone
>*except* your own QSO.
>
>While both are important it is the IMD that represents a "spurious"
>signal outside the bandwidth required for communication - typically fie 
>to ten KHz above and below the desired RF.
>

Yes, I understand completely.  From a "Real World Practical" standpoint, if
I have a really clean transmitter with lovely IMD specifications and I stuff
over compressed, highly processed, all compressor-limiter knobs to the right
audio into it I will get completely unintelligible audio with wonderful
technical specifications and still bother my neighbors.

And don't forget. Some contesters *WANT* the scenario you described above.
No sense in sweeping that under the rug!

That's my point.  I'm being responsible in keeping my IMD products from
raising the noise floor on the bands, but the OB down the street with his
FT101E, "Power Mic" and  4 EL509  sweep tube amp promptly blasts me out of
the pileup. 

I'm not saying that the pursuit of technical excellence in amateur
transmitters is a bad thing, but life is a constant compromise between
technical excellence and "good enough".  Sometimes "close enough!  Now ship
it so we can make a profit!" is the true measure of excellence in the real
world. That doesn't mean we should accept poor engineering, all it means is
that excellence is always a tradeoff, and not only about "numbers".  

Will the OB down the street care enough to change?  That's the ultimate
variable in the equation, isn't it?   

-lu-


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Vic Rosenthal

As I think I remember, in California the limit was 1500 watts, unless you were 
calling an ATNO (all-time new one) in which case it was 5 kW.

Vic 4X6GP/K2VCO 

> On 30 Oct 2015, at 12:55 AM, Doug Turnbull  wrote:
> 
> Of course this is a comparison of these two amps.   Please note that
> 1500 Watts is only used for contests which we are allowed to use for some
> contests in EI but not for regular operating where our power limit is 400W
> output.
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Ron D'Eau Claire

Rich. I have been building radios since 1949 and a Ham since 1952. One of
the first things I learned to appreciate is that good Hams operate their
rigs to produce the cleanest signal possible. If it's a factory built, that
means running it as recommended by the manufacturer. But that does not mean
you are running the latest and most sophisticated rig on the air. 

At the risk of starting an O.T. thread, let me point out that it is 100% as
legal and proper to run a 1948 El-tronics transmitter or a E.F. Johnson
Viking I as it is a current K3S. Sure, the newer rig is likely cleaner than
the old stuff, but that is not the issue. The sign of an A-1 operator is in
getting the best out of what he has, not buying the best on the market. 

That has been true since the earliest days of Ham radio.  And the FCC in the
USA has always supported the idea. (The only thing that is NOT allowed is
spark (damped wave) emissions.)

When I was in school and started designing receivers for a hobby in the
1950's one of the first things I learned is that engineering is not about
achieving perfection. It is achieving what is practical. All engineering is
a trade-off - a compromise - between an imagined ideal and what is possible
given the parts at hand, the time and money available. 

Amateur radio is a hobby. It's what we do for fun and in the USA the FCC
supports that too. 

To heck with "phase noise" or other issues. If your rig chirps a bit when
keyed or drifts a bit so I have to ride the VFO, I'll in line to work you
and learn a bit about what you are running. And if it's a rig that should
not be chirping in CW, or drifting a bit, I'll be first in line to offer my
assistance if you want it. 

73, Ron AC7AC




-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Rich
Sent: Thursday, October 29, 2015 8:35 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] IMD and supply voltage

Guys,

This comment in no way is mean spirited, but truly a concern after reading
all of this tech data.

For those of us who do not have 100K in test equipment and a EE,  I am 
starting to feel like I should not even get on the air.   I get the 
concept, but the best I can do is make good clean connections, do not
overdrive my audio and hope for the best.  I have to have faith in the
equipment builders or find a new hobby.

Rich

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Rich


Guys,

This comment in no way is mean spirited, but truly a concern after 
reading all of this tech data.


For those of us who do not have 100K in test equipment and a EE,  I am 
starting to feel like I should not even get on the air.   I get the 
concept, but the best I can do is make good clean connections, do not 
overdrive my audio and hope for the best.  I have to have faith in the 
equipment builders or find a new hobby.


Rich
On 10/29/2015 10:52 PM, Joe Subich, W4TV wrote:


On 10/29/2015 5:53 PM, Luis V. Romero wrote:


Processing issues heard on the air today simply make the discussion 
of final

amplifier spectral purity moot.




Comparing processing issues and transmitter IMD are mixing apple and
oranges.  Processing issues generally affect the quality of signal
*on channel* - the ability to understand the audio - whilst IMD is the
"off frequency" splatter up/down the band that interferes with everyone
*except* your own QSO.

While both are important it is the IMD that represents a "spurious"
signal outside the bandwidth required for communication - typically 
fie to ten KHz above and below the desired RF.


73,

   ... Joe, W4TV
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rwnewbo...@comcast.net



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Joe Subich, W4TV



On 10/29/2015 5:53 PM, Luis V. Romero wrote:


Processing issues heard on the air today simply make the discussion of final
amplifier spectral purity moot.




Comparing processing issues and transmitter IMD are mixing apple and
oranges.  Processing issues generally affect the quality of signal
*on channel* - the ability to understand the audio - whilst IMD is the
"off frequency" splatter up/down the band that interferes with everyone
*except* your own QSO.

While both are important it is the IMD that represents a "spurious"
signal outside the bandwidth required for communication - typically fie 
to ten KHz above and below the desired RF.


73,

   ... Joe, W4TV
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Wes (N7WS)

IMD is not a single number, even at a fixed supply voltage and power output.  
Recent measurements that I have performed on my K3 show a significant variation 
in IMD vs. frequency.  For example, at 30W (V+ 14.5V), the IMD of my K3, varied 
from -58 dB (relative to PEP*) at 3.8 MHz to -40 dB at 14 MHz.  Both of these 
numbers are astoundingly good, but get worse at 100W, as expected, and get much 
worse at 10W, which is not. And you don't even want to think about it at 12W.


I have it on excellent authority that no one understands this IMD variation with 
respect to frequency.


As to a rule of thumb for IMD dB per volt, IMHO, there isn't one. A 1 volt 
change from 11 to 12 might be fairly significant; a change from 14 to 15, not so 
much.


* Some words about the numbers.  I believe, and a number of professional 
(Collins, EIMAC) and military specifications agree with me, that the IMD 
products should be compared to the level of one of the two fundamental spectral 
components.  ARRL, Elecraft and every other ham equipment manufacturer compare 
the IMD products to the PEP of the two fundamental spectral components. So when 
they measure -24 dBc on a spectrum analyzer they add -6 dB and call the IMD -30 
dBc.  Your receiver is an unswept spectrum analyzer; it isn't fooled by the 
slight-of-hand.



On 10/29/2015 8:09 AM, frank wrote:

This subject keeps cropping up.  Is this a serious issue ?

I have heard that IMD improves by 10db with a one volt increase in supply 
voltage.  Is this really the case or just a measurement error?  10db is a large 
difference.  One volt is a small variation.

What is the minimum acceptable IMD?  How linear does the amp need to be?  If 
36db is better than 26db is 100db even better or just overkill?

Are other solid state amplifier products similarly effected?

What is the IMD performance of the K3S at 10 watts over a supply voltage 
variation from 11 volts to 14.7 volts?  I ask because I believe those ten watts 
are generated by Dmos devices as well.  Do these devices only misbehave with 
varying supply voltage at higher (100w) power levels and lower supply voltages?

Should I wait to purchase a K3S until this issue is resolved?  (Assuming this 
is a valid issue)

Back in the good old days we used to solve problems.  Today we don't have 
problems, just issues.



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Gary

Eric,
I have learnt a lot reading the posts, thanks for being tolerant.

Gary 

-Original Message-
From: "Eric Swartz - WA6HHQ, Elecraft" 
Sent: ‎30/‎10/‎2015 10:53 AM
To: "Matthew Cook" ; "frank" 
Cc: "Elecraft Reflector" 
Subject: Re: [Elecraft] IMD and supply voltage

Folks - we're also hitting the posting limit for this topic. To avoid overload 
for other readers, lets wind it down tonight and then close the thread..

73

Eric
List Moderation, LLC
/elecraft.com/
---
On 10/29/2015 4:57 PM, Matthew Cook wrote:
> Frank,
>
> Actually No.
>
> You can build solid state 125Wpep HF amplifiers with TX IMD figures better
> than  -42dBc that operate quite happily at full power with only 11V.
> Unfortunately they are typically designed and built by Military and
> Commercial HF manufacturers

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to vk1zzg...@gmail.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Eric Swartz - WA6HHQ, Elecraft

Folks - we're also hitting the posting limit for this topic. To avoid overload 
for other readers, lets wind it down tonight and then close the thread..


73

Eric
List Moderation, LLC
/elecraft.com/
---
On 10/29/2015 4:57 PM, Matthew Cook wrote:

Frank,

Actually No.

You can build solid state 125Wpep HF amplifiers with TX IMD figures better
than  -42dBc that operate quite happily at full power with only 11V.
Unfortunately they are typically designed and built by Military and
Commercial HF manufacturers


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Bill Frantz

It looks like there might be a business opportunity for an 
external 100W amp which has very low distortion. Via auxbus it 
could be slaved to a K3, K3S, or a KX3. How does the KXPA100 
stack up?



Re: Overdriving speech processors

K1N team member Glenn Johnson, W0GJ, said, “It seems like 
everyone tries to turn up their microphone gain and speech 
processors to overdrive and it creates splatter and makes it 
almost impossible and if we could somehow magically eliminate 
all speech processors, we could probably double or triple our 
rate."[1] He also said that European stations were worse 
offenders than US stations.


[1] Interview with Glenn Johnson WØGJ , K1N co-team leader by 
Wolf Harranth, OE1WHC of Dokumentationsarchiv Funk, a history of 
radio site 


73 Bill AE6JV

---
Bill Frantz| Ham radio contesting is a| Periwinkle
(408)356-8506  | contact sport.   | 16345 
Englewood Ave
www.pwpconsult.com |  - Ken Widelitz K6LA / VY2TT | Los Gatos, 
CA 95032


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Matthew Cook

Frank,

Actually No.

You can build solid state 125Wpep HF amplifiers with TX IMD figures better
than  -42dBc that operate quite happily at full power with only 11V.
Unfortunately they are typically designed and built by Military and
Commercial HF manufacturers who then have to recover their development
costs with very high transceiver prices.  I don't think most Hamsters will
want to pay for the amortised development costs, they are not insignificant.

The last commercial BJT HF amplifier design that I was involved with
required ~6 man years of development work and easily made the above
specs/grade, this was done 9 years ago.  However while the FCC and other
regulatory bodies don't make the specifications for Amateur gear better,
then there wont really be any serious developments in this area why would
you?

However there are an equal amount of poorly designed tube amplifiers c.f
solid state amplifiers on the air waves, so this phenomenon is not uncommon.

Oh the K3/K3s 100W power amplifier is certainly well above par, especially
when kept around 30Wpep; just the right amount of power to feed the KPA500
or well designed QRO tube amp.

73

Matthew
VK5ZM

On 30 October 2015 at 10:11, frank  wrote:

> On Thu, 29 Oct 2015 15:21:05 -0700
> Wayne Burdick  wrote:
>
> > Yes, we made sure compression was off. We gave the unit every
> opportunity to exhibit magic properties. Alas, it did not.
> >
> > Wayne
> > N6KR
> >
>
>
> Sounds like all solid state amps offering more than about 50 watts are
> having growing pains.  It does not make much sense investing in something
> you might need to trash in a few years when someone decides to design a
> decent solid state amp or the chip designers create a magic power device.
>
> For my money its a K3S/10 and a homebrew 6146 run off a mobile power
> supply.
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to vk...@bistre.net
>
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Doug Turnbull

Frank,
 Maybe when the devices come out Elecraft will bring out a new power
amplifier module to replace the older module for both K3 and KX3.
Meanwhile run the K3 at lower power and drive an external vacuum tube or
solid state power amplifier.

  My experience of an Acom 2000A, a tube amp and an SPE Expert 2K-FA, a
solid state amp is that:
1) Solid State amps are instant on and this is a big plus.
2) Solid State amps do not heat the shack to the same degree.
3) Solid State amps are much more particular as to load and if the SWR is at
all high without being tuned out by matching the load then distortion is
horrific. 
4) The Acom 2000A is much more tolerant of operating for long periods flat
out at 1500 Watts.

  Of course this is a comparison of these two amps.   Please note that
1500 Watts is only used for contests which we are allowed to use for some
contests in EI but not for regular operating where our power limit is 400W
output.

73 Doug EI2CN

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of frank
Sent: 29 October 2015 23:42
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] IMD and supply voltage

On Thu, 29 Oct 2015 15:21:05 -0700
Wayne Burdick  wrote:

> Yes, we made sure compression was off. We gave the unit every opportunity
to exhibit magic properties. Alas, it did not. 
> 
> Wayne
> N6KR
> 

Sounds like all solid state amps offering more than about 50 watts are
having growing pains.  It does not make much sense investing in something
you might need to trash in a few years when someone decides to design a
decent solid state amp or the chip designers create a magic power device.

For my money its a K3S/10 and a homebrew 6146 run off a mobile power supply.

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to turnb...@net1.ie

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread frank

On Thu, 29 Oct 2015 15:21:05 -0700
Wayne Burdick  wrote:

> Yes, we made sure compression was off. We gave the unit every opportunity to 
> exhibit magic properties. Alas, it did not. 
> 
> Wayne
> N6KR
> 

Sounds like all solid state amps offering more than about 50 watts are having 
growing pains.  It does not make much sense investing in something you might 
need to trash in a few years when someone decides to design a decent solid 
state amp or the chip designers create a magic power device.

For my money its a K3S/10 and a homebrew 6146 run off a mobile power supply.

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Wayne Burdick

Greg,

Even a rig with predistortion capability will run out of steam and exhibit 
greater IMD when running from low supply voltages. Predistortion attempts to 
compensate for the compression by increasing drive, but there must be enough 
headroom to allow the algorithm to work. Note that the rear panel of the ANAN 
100D specifies "13.8V DC". I doubt that the ARRL did any testing at lower 
voltages. There are other situations where inadequate headroom might come into 
play, too, such as when driving a somewhat reactive load that causes the 
transmitter to hit a current limit.

While this particular radio emphasizes predistortion, there's more than that 
involved in keeping the bands clean. Figure 3 of the QST review for the rig 
(page 47) shows transmit phase noise that is about 15 dB higher than a 
K3+KSYN3A or a K3S at a 100-kHz offset. This 15 dB of additional wideband noise 
would in many situations (such as FD or multi-transmitter stations) cancel out 
the value obtained with predistortion.

73,
Wayne
N6KR

On Oct 29, 2015, at 2:07 PM, Gregory Schippers  wrote:

> I personally found the recent review in QST of the ANAN 100D using
> pre-distortion to lower TX distortion products to be the most exciting
> thing I have read in that rag in a LONG time. I DO hope they are
> setting a standard that others will strive for. It was so much better
> than any other rig they have ever tested, that is was literally "off
> the chart".  Not sure I want a rig controlled ONLY with a computer
> interface, but this might sway my decision to at least try one!
> 
> Greg in West Mitten, KC8HXO
> 
> On Thu, Oct 29, 2015 at 2:58 PM, Jim Brown  wrote:
>> On Thu,10/29/2015 12:06 PM, frank wrote:
>>> 
>>> Also, you did not answer my questions.  Maybe I should ask them one at a
>>> time.
>> 
>> 
>> I thought Wayne answered them quite well, but I'll try to rephrase his
>> answers in terms that are easier to understand.
>> 
>> 1) Contemporary ham rigs are designed to operate from automotive DC voltages
>> as a matter of convenience.
>> 
>> 2) The output transistors used in these rigs produce less distortion at
>> higher supply voltages.
>> 
>> 3) Most rigs are optimized for 13.8 - 14 VDC, and are tested at that level
>> by ARRL.
>> 
>> 4) Most commercial power supplies marketed to hams are regulated to 13.8 -
>> 14.5 VDC, and that voltage is internally adjustable.
>> 
>> 5) Most rigs will work at lower DC power supply voltages.
>> 
>> 6) When operated at lower DC power supply voltage, their distortion will
>> increase.
>> 
>> 7) When operated above their design output power, distortion will increase.
>> 
>> 8) Doing both 6 and 7 will increase distortion even more.
>> 
>> 9) Distortion in the K3 and K3S output stage is specified for full power
>> output at 13.8 - 14 VDC, and distortion is greatly reduced when run at lower
>> power levels.
>> 
>> My own comments:
>> 
>> Distortion causes the most QRM when running high power. Many of the best
>> power amps reach full power with drive power in the range of 50-60 W -- the
>> KPA500 needs about 28W, my Titans (I have three) need between 40-60W,
>> depending on condition of the tubes and the operating frequency. An ACOM
>> 1010 needs between 50 and 70 watts, again depending on the operating
>> frequency.
>> 
>>> This is state of the art?
>> 
>> How much do you want to pay for "state of the art?" How about the infamous
>> pentagon $800 hammer?
>> 
>> According to ARRL measurements, the K3 produces the cleanest CW signal of
>> any current rig. See my summary of their published data in the following
>> link
>> 
>> k9yc.com/TXNoise.pdf
>> 
>> See my measurements of my K3 and several other rigs in this link
>> 
>> http://k9yc.com/P3_Spectrum_Measurements.pdf
>> 
>> 73, Jim K9YC
>> 
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to kc8h...@gmail.com
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to n...@elecraft.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Wayne Burdick

Yes, we made sure compression was off. We gave the unit every opportunity to 
exhibit magic properties. Alas, it did not. 

Wayne
N6KR


On Oct 29, 2015, at 2:10 PM, Chip Stratton  wrote:

> Interesting results about the Icom M-802. It is actually marketed as a "150 
> Watt" rig, so testing it at 100 Watts would be giving it even more "benefit 
> of the doubt".
> 
> It is also interesting to note that Icom has disabled speech compression in 
> the M-802 by default. Apparently, when compression is enabled the transmitter 
> doesn't meet FCC requirements for use on the marine bands. I suspect that 
> what this means is that the M-802 is normally driven far below 150 Watts PEP 
> or even 100 Watts PEP when used without voice compression.
> 
> 73
> Chip
> AE5KA



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Gary

Walt,

Spot on.

It is frustrating to operate in a contest as much as I enjoy the challenge, the 
vast majority of strong signals are many times, disturbing to listen to.
I make a point of complimenting good audio even in the heat of battle.

Gary 

-Original Message-
From: "Luis V. Romero" 
Sent: ‎30/‎10/‎2015 7:54 AM
To: "elecraft@mailman.qth.net" 
Subject: Re: [Elecraft] IMD and supply voltage

Bob, et. Al:

 

> 

>Signal reports heard being given today are largely "ego reports" and are 

>of little to no value.  When was the last time you heard a report 

>indicating ones audio is distorted, or sounds like the transmitter has a 

>bit of FM, or there's buck shot heard 10 kHz away, or there's a noise, 

>humm or a buzz on your signal?   Nope, we don't want to offend anyone 

>and thus seemingly just roll out a meaningless, non constructive 

>report.  I suppose to many of us have forgotten what we learned; "if you 

>can't say something nice, then don't say anything at all".

> 

 

Well, you obviously have not worked me :)

 

Audio transmission quality is a subject close to my heart.  While I
understand all the technical issues regarding Intermodulation Distortion in
12v vs 48 volt and Tube vs Solid State amps, the proof is in the pudding:
Just listen on the air! You will find folks running Class A rigs that sound
horrible due to overprocessing and the belief that turning all the transmit
audio knobs all the way to ELEVEN and seeing dancing meters make for great
signals.

 

Processor missadjustment is a worse culprit than IMD and, although IMD
products do harm, processor knobs turned all the way to the right are the
main culprit in the mess that has become our SSB subbands.  There are some
operators I can't understand at all.  Worse, some of the "Audio VooDoo" ESSB
types have so much bass that they create a phantom carrier, making their
signal copyable in AM mode.  On many of these, I even able to lock my
WinRadio SDR to the pseudo carrier in Synchronous AM mode!  

 

In the last CQ WW SSB, I started to think that my signal was too clean and
too bandwidth efficient versus my "competitors".  That lovely, raspy, sharp,
dense MP1000 sound (not to blame a particular radio, but I know how to make
that one sound that way), while certainly "penetrating", is difficult to
listen to, and, when overdone, makes it hard to understand.  That means lost
QSO's.  Want to increase your score?  Consider making better audio!  

 

Overdone processing by and large creates listener fatigue and
intelligibility problems.  A 10 second contest QSO, while not creating
fatigue on its own, when joined by 300 of them, will.  Wonder why you are
tired after a short stint on 40m in WorldWide Friday night?  This might be
the answer!Transmitter IMD in this scenario is still there, however,
exacerbating the problem.  And some contesters will use their IMD "wideness"
as a weapon of advantage in the competition.

 

There is nothing we can do in our receivers to counteract this.  We are at
their mercy. Where is the Wouff Hong and the Rettysnich? We need you now
more than ever!

 

If we are going to campaign against anything, I would say campaign against
over-processing.  Once we get them to understand that issue, then we can
concentrate on IMD. 

 

With some of the signals I hear on the air today, IMD is the least of our
worry in a world where everybody is Fine Nine oh Five.

 

Audio quality is a very personal thing, like your car choice, radio choice
or your hair coloring chemical choices... I wish everyone had the common
sense to make articulate, clear, yet punchy and "communications quality"
audio by avoiding the temptation to eke out that last watt.  When we all do
that, then we can worry about Amplifier IMD.

 

Processing issues heard on the air today simply make the discussion of final
amplifier spectral purity moot.

 

Respectfully

 

Lu - W4LT

K-Line

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to vk1zzg...@gmail.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Luis V. Romero

Bob, et. Al:

 

> 

>Signal reports heard being given today are largely "ego reports" and are 

>of little to no value.  When was the last time you heard a report 

>indicating ones audio is distorted, or sounds like the transmitter has a 

>bit of FM, or there's buck shot heard 10 kHz away, or there's a noise, 

>humm or a buzz on your signal?   Nope, we don't want to offend anyone 

>and thus seemingly just roll out a meaningless, non constructive 

>report.  I suppose to many of us have forgotten what we learned; "if you 

>can't say something nice, then don't say anything at all".

> 

 

Well, you obviously have not worked me :)

 

Audio transmission quality is a subject close to my heart.  While I
understand all the technical issues regarding Intermodulation Distortion in
12v vs 48 volt and Tube vs Solid State amps, the proof is in the pudding:
Just listen on the air! You will find folks running Class A rigs that sound
horrible due to overprocessing and the belief that turning all the transmit
audio knobs all the way to ELEVEN and seeing dancing meters make for great
signals.

 

Processor missadjustment is a worse culprit than IMD and, although IMD
products do harm, processor knobs turned all the way to the right are the
main culprit in the mess that has become our SSB subbands.  There are some
operators I can't understand at all.  Worse, some of the "Audio VooDoo" ESSB
types have so much bass that they create a phantom carrier, making their
signal copyable in AM mode.  On many of these, I even able to lock my
WinRadio SDR to the pseudo carrier in Synchronous AM mode!  

 

In the last CQ WW SSB, I started to think that my signal was too clean and
too bandwidth efficient versus my "competitors".  That lovely, raspy, sharp,
dense MP1000 sound (not to blame a particular radio, but I know how to make
that one sound that way), while certainly "penetrating", is difficult to
listen to, and, when overdone, makes it hard to understand.  That means lost
QSO's.  Want to increase your score?  Consider making better audio!  

 

Overdone processing by and large creates listener fatigue and
intelligibility problems.  A 10 second contest QSO, while not creating
fatigue on its own, when joined by 300 of them, will.  Wonder why you are
tired after a short stint on 40m in WorldWide Friday night?  This might be
the answer!Transmitter IMD in this scenario is still there, however,
exacerbating the problem.  And some contesters will use their IMD "wideness"
as a weapon of advantage in the competition.

 

There is nothing we can do in our receivers to counteract this.  We are at
their mercy. Where is the Wouff Hong and the Rettysnich? We need you now
more than ever!

 

If we are going to campaign against anything, I would say campaign against
over-processing.  Once we get them to understand that issue, then we can
concentrate on IMD. 

 

With some of the signals I hear on the air today, IMD is the least of our
worry in a world where everybody is Fine Nine oh Five.

 

Audio quality is a very personal thing, like your car choice, radio choice
or your hair coloring chemical choices... I wish everyone had the common
sense to make articulate, clear, yet punchy and "communications quality"
audio by avoiding the temptation to eke out that last watt.  When we all do
that, then we can worry about Amplifier IMD.

 

Processing issues heard on the air today simply make the discussion of final
amplifier spectral purity moot.

 

Respectfully

 

Lu - W4LT

K-Line

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Chip Stratton

Interesting results about the Icom M-802. It is actually marketed as a "150
Watt" rig, so testing it at 100 Watts would be giving it even more "benefit
of the doubt".

It is also interesting to note that Icom has disabled speech compression in
the M-802 by default. Apparently, when compression is enabled the
transmitter doesn't meet FCC requirements for use on the marine bands. I
suspect that what this means is that the M-802 is normally driven far below
150 Watts PEP or even 100 Watts PEP when used without voice compression.

73
Chip
AE5KA

On Thu, Oct 29, 2015 at 3:39 PM, Wayne Burdick  wrote:

> Jim,
>
> This appears to *not* be true, at least for one radio lauded by those
> concerned about TX IMD.
>
> Earlier this year there was a long forum thread on Eham.net lamenting the
> "fact" that 12-V ham rigs were not as clean as 12-V marine rigs. One radio
> in particular, the Icom M802, was touted by forum participants as having
> far better IMD specs than any 12-V ham transceiver.
>
> We downloaded the manual for we this radio and found that Icom was using
> the same devices and essentially the same amplifier circuit that we were.
> Still, we gave them the benefit of the doubt and purchased a new Icom M802
> (from Amazon, $1813) to test in our own lab.
>
> We very carefully measured transmit IMD at 100 watts on several channels,
> covering the full range of the HF marine band. Here is an example plot from
> about 12.28 MHz:
>
>http://www.elecraft.com/Icom%20M802%20100-W%20IMD.jpeg
>
> This plot shows the two 3rd-order products being down by about 27 and 30
> dBc, respectively. A plot for the Elecraft K3 posted earlier on this same
> forum showed these tones down 33 and 36 dBc--about a 6-dB improvement over
> this particular marine radio.
>
> A bit on our test setup: We used a very clean 14.0 V DC power supply with
> short cables, a high-performance analog 2-tone generator, and a very hefty
> 50-ohm nonreactive dummy load. We set the top of the spectral plot at 100 W
> and equalized the amplitude of the tones at -6 dBc, consistent with the
> usual ARRL method. The tests were done by our senior RF engineer, and I'm
> sure he was not overdriving the spectrum analyzer :)
>
> Chances are that virtually all marine HF SSB radios being made today are
> using the same 100-W MOSFET PAs that we and other ham manufacturers do. As
> far as we can tell, there is no magic in the marine radios that is making
> them better. On the other hand, their marketing department may be better
> funded.
>
> If you have another marine radio in mind that you think is using
> different/better circuitry, please let me know so we can repeat this
> exercise if necessary.
>
> 73,
> Wayne
> N6KR
>
>
>
> On Oct 29, 2015, at 1:04 PM, jim  wrote:
>
> > Jim,
> >
> > The marine divisions of Kenwood, et.al. already have low cost, low
> voltage,
> > PA solutions with better IMD specs, primarily due to channel spacing for
> the
> > marine band.
> >
> > Jim
> >
> > W6AIM
>
>
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to lightdazz...@gmail.com
>
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Gregory Schippers

I personally found the recent review in QST of the ANAN 100D using
pre-distortion to lower TX distortion products to be the most exciting
thing I have read in that rag in a LONG time. I DO hope they are
setting a standard that others will strive for. It was so much better
than any other rig they have ever tested, that is was literally "off
the chart".  Not sure I want a rig controlled ONLY with a computer
interface, but this might sway my decision to at least try one!

Greg in West Mitten, KC8HXO

On Thu, Oct 29, 2015 at 2:58 PM, Jim Brown  wrote:
> On Thu,10/29/2015 12:06 PM, frank wrote:
>>
>> Also, you did not answer my questions.  Maybe I should ask them one at a
>> time.
>
>
> I thought Wayne answered them quite well, but I'll try to rephrase his
> answers in terms that are easier to understand.
>
> 1) Contemporary ham rigs are designed to operate from automotive DC voltages
> as a matter of convenience.
>
> 2) The output transistors used in these rigs produce less distortion at
> higher supply voltages.
>
> 3) Most rigs are optimized for 13.8 - 14 VDC, and are tested at that level
> by ARRL.
>
> 4) Most commercial power supplies marketed to hams are regulated to 13.8 -
> 14.5 VDC, and that voltage is internally adjustable.
>
> 5) Most rigs will work at lower DC power supply voltages.
>
> 6) When operated at lower DC power supply voltage, their distortion will
> increase.
>
> 7) When operated above their design output power, distortion will increase.
>
> 8) Doing both 6 and 7 will increase distortion even more.
>
> 9) Distortion in the K3 and K3S output stage is specified for full power
> output at 13.8 - 14 VDC, and distortion is greatly reduced when run at lower
> power levels.
>
> My own comments:
>
> Distortion causes the most QRM when running high power. Many of the best
> power amps reach full power with drive power in the range of 50-60 W -- the
> KPA500 needs about 28W, my Titans (I have three) need between 40-60W,
> depending on condition of the tubes and the operating frequency. An ACOM
> 1010 needs between 50 and 70 watts, again depending on the operating
> frequency.
>
>> This is state of the art?
>
> How much do you want to pay for "state of the art?" How about the infamous
> pentagon $800 hammer?
>
> According to ARRL measurements, the K3 produces the cleanest CW signal of
> any current rig. See my summary of their published data in the following
> link
>
> k9yc.com/TXNoise.pdf
>
> See my measurements of my K3 and several other rigs in this link
>
> http://k9yc.com/P3_Spectrum_Measurements.pdf
>
> 73, Jim K9YC
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to kc8h...@gmail.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Bob McGraw - K4TAX

I agree Jim.  Many hams do not understand what IMD values mean and how 
it affects other signals on the bands.  To wit, the "on frequency" 
signal is not affected, the IMD is not heard on frequency, so it is of 
little concern to the operator as they are only concerned about getting 
a big signal report.  However, a transmitter and/or amplifier spewing 
garbage across the entire band affects all of us.  We fight noise and 
QRM most aggressively with receivers.  Some of this noise we must deal 
with is IMD from adjacent stations often some 5 kHz to 20 kHz or more.  
The ones I simply detest are the operators that say "my station sounds 
great" not realizing the amount of garbage he's spewing up and down the 
band for the rest of use to deal with.


Signal reports heard being given today are largely "ego reports" and are 
of little to no value.  When was the last time you heard a report 
indicating ones audio is distorted, or sounds like the transmitter has a 
bit of FM, or there's buck shot heard 10 kHz away, or there's a noise, 
humm or a buzz on your signal?   Nope, we don't want to offend anyone 
and thus seemingly just roll out a meaningless, non constructive 
report.  I suppose to many of us have forgotten what we learned; "if you 
can't say something nice, then don't say anything at all".


We talk about the level of electronic noise which is heard today as 
opposed to what we heard 20 or so years ago.  Well, the IMD component is 
part of that electronic noise.


Yes I would agree the technology is available and that company's should 
or could design radios to attain at least a 10 dB improvement in IMD 
numbers.  Yes, the ARRL does represent a majority of the hams in the US 
area.  I would certainly like to see them petition the FCC for improved 
specs in this regard.


73
Bob, K4TAX

On 10/29/2015 12:37 PM, jim wrote:

How about 80 watts instead.

Won't make a noticeable difference on the receive end.

Even better, get rid of all the Yaesu and Icom "Clackers" with their VERY
poor CW performance.  You can have the best class A amplifier in the world,
but garbage in will always equal garbage out.

I am ashamed at our "leaders" at the ARRL for not petitioning the FCC for
better specs.  The technology is there, they all use it in their business
radios that have a better spec.

Oh, I forgot, follow the money and take the advertising monies from these
clackers

Jim
W6AIM



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Wayne Burdick

Jim,

This appears to *not* be true, at least for one radio lauded by those concerned 
about TX IMD.

Earlier this year there was a long forum thread on Eham.net lamenting the 
"fact" that 12-V ham rigs were not as clean as 12-V marine rigs. One radio in 
particular, the Icom M802, was touted by forum participants as having far 
better IMD specs than any 12-V ham transceiver.

We downloaded the manual for we this radio and found that Icom was using the 
same devices and essentially the same amplifier circuit that we were. Still, we 
gave them the benefit of the doubt and purchased a new Icom M802 (from Amazon, 
$1813) to test in our own lab.

We very carefully measured transmit IMD at 100 watts on several channels, 
covering the full range of the HF marine band. Here is an example plot from 
about 12.28 MHz:

   http://www.elecraft.com/Icom%20M802%20100-W%20IMD.jpeg

This plot shows the two 3rd-order products being down by about 27 and 30 dBc, 
respectively. A plot for the Elecraft K3 posted earlier on this same forum 
showed these tones down 33 and 36 dBc--about a 6-dB improvement over this 
particular marine radio. 

A bit on our test setup: We used a very clean 14.0 V DC power supply with short 
cables, a high-performance analog 2-tone generator, and a very hefty 50-ohm 
nonreactive dummy load. We set the top of the spectral plot at 100 W and 
equalized the amplitude of the tones at -6 dBc, consistent with the usual ARRL 
method. The tests were done by our senior RF engineer, and I'm sure he was not 
overdriving the spectrum analyzer :)

Chances are that virtually all marine HF SSB radios being made today are using 
the same 100-W MOSFET PAs that we and other ham manufacturers do. As far as we 
can tell, there is no magic in the marine radios that is making them better. On 
the other hand, their marketing department may be better funded.

If you have another marine radio in mind that you think is using 
different/better circuitry, please let me know so we can repeat this exercise 
if necessary.

73,
Wayne
N6KR

On Oct 29, 2015, at 1:04 PM, jim  wrote:

> Jim,
> 
> The marine divisions of Kenwood, et.al. already have low cost, low voltage,
> PA solutions with better IMD specs, primarily due to channel spacing for the
> marine band.
> 
> Jim
> 
> W6AIM

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Guy Olinger K2AV

My internal K3 readings of 14.3V idle and 14.0V at the 35w PEP out needed
to drive my Alpha 8410 to 1200 or 1300 watts out, probably is pretty good
IMD. The idle current is ~1.3 amps. Tune at 35 watts into 1:1 SWR is 8.7
amps. That's .04 ohms in the cabling. I don't have anything to directly
measure that.

At that point, the tuning of the Alpha would has more to do with the
over-the-air IMD than the K3.

Wouldn't predistortion need to be external to the K3, dynamic based on
sampling the output of the amp, and converted into some DSP friendly format
fed to the K3 CPU?

73, Guy K2AV

On Thu, Oct 29, 2015 at 3:52 PM, Joe Subich, W4TV  wrote:

>
> CW is just one mode and is the easiest to "get right" as far as the PA
> is concerned.  CW bandwidth is determined primarily by keying shape and
> phase noise in the synthesizer (or D to A clock jitter).
>
> The K3/K3S is far from the cleanest rig when it comes to SSB on any of
> the audio based digital modes.  All of the rigs using 48V finals have
> IMD products many dB less than the K3/K3S - particularly when the
> K3/K3S is being run from a partially discharged battery.
>
> However, even rigs with 48V finals are notably more dirty than many of
> the rigs that used tube type finals (particularly the 6146) of 40 years
> ago.
>
> Amateur rigs need predistortion - particularly those with "12V" finals -
> to get SSB (and data mode) IMD below -50 dBc (-44 dB PEP) as a starting
> point or "12V" radios should be limited by their makers to 60-80W where
> the IMD is much lower than at 100-120W levels.
>
> For ARRL to have silently watched transmit IMD degrade by nearly 20 dB
> in the last 40 years and not raised the issue is unconscionable.
>
> Lest anyone think I'm picking on Elecraft ... the IMD issues are the
> same in many solid state amplifiers, they are rated for saturated
> conditions which drive up IMD.  Most are significantly less dirty when
> operated at 60-75% of rated PEP output unless the designer has built in
> a significant amount of negative feedback.  When a 1200W PEP amplifier
> has only 8 150W transistors or or a 600 W amplifier has only two 300 W
> transistors that's a good sign the amplifier can not possibly be clean
> at its rated output.
>
> 73,
>
>... Joe, W4TV
>
> On Thu, Oct 29, 2015 at 2:58 PM, Jim Brown 
>> wrote:
>>
>> According to ARRL measurements, the K3 produces the cleanest CW signal of
>>> any current rig. See my summary of their published data in the following
>>> link
>>>
>>> k9yc.com/TXNoise.pdf
>>>
>>> See my measurements of my K3 and several other rigs in this link
>>>
>>> http://k9yc.com/P3_Spectrum_Measurements.pdf
>>>
>>> 73, Jim K9YC
>>>
>>> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k2av@gmail.com
>
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread jim

Jim,

The marine divisions of Kenwood, et.al. already have low cost, low voltage,
PA solutions with better IMD specs, primarily due to channel spacing for the
marine band.

Jim

W6AIM

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim
Brown
Sent: Thursday, October 29, 2015 11:58 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] IMD and supply voltage

On Thu,10/29/2015 12:06 PM, frank wrote:
> Also, you did not answer my questions.  Maybe I should ask them one at a
time.

I thought Wayne answered them quite well, but I'll try to rephrase his
answers in terms that are easier to understand.

1) Contemporary ham rigs are designed to operate from automotive DC voltages
as a matter of convenience.

2) The output transistors used in these rigs produce less distortion at
higher supply voltages.

3) Most rigs are optimized for 13.8 - 14 VDC, and are tested at that level
by ARRL.

4) Most commercial power supplies marketed to hams are regulated to 13.8
- 14.5 VDC, and that voltage is internally adjustable.

5) Most rigs will work at lower DC power supply voltages.

6) When operated at lower DC power supply voltage, their distortion will
increase.

7) When operated above their design output power, distortion will increase.

8) Doing both 6 and 7 will increase distortion even more.

9) Distortion in the K3 and K3S output stage is specified for full power
output at 13.8 - 14 VDC, and distortion is greatly reduced when run at lower
power levels.

My own comments:

Distortion causes the most QRM when running high power. Many of the best
power amps reach full power with drive power in the range of 50-60 W -- the
KPA500 needs about 28W, my Titans (I have three) need between 40-60W,
depending on condition of the tubes and the operating frequency. 
An ACOM 1010 needs between 50 and 70 watts, again depending on the operating
frequency.

 > This is state of the art?

How much do you want to pay for "state of the art?" How about the infamous
pentagon $800 hammer?

According to ARRL measurements, the K3 produces the cleanest CW signal of
any current rig. See my summary of their published data in the following
link

k9yc.com/TXNoise.pdf

See my measurements of my K3 and several other rigs in this link

http://k9yc.com/P3_Spectrum_Measurements.pdf

73, Jim K9YC

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to jbol...@outlook.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Joe Subich, W4TV



CW is just one mode and is the easiest to "get right" as far as the PA
is concerned.  CW bandwidth is determined primarily by keying shape and
phase noise in the synthesizer (or D to A clock jitter).

The K3/K3S is far from the cleanest rig when it comes to SSB on any of
the audio based digital modes.  All of the rigs using 48V finals have
IMD products many dB less than the K3/K3S - particularly when the
K3/K3S is being run from a partially discharged battery.

However, even rigs with 48V finals are notably more dirty than many of
the rigs that used tube type finals (particularly the 6146) of 40 years
ago.

Amateur rigs need predistortion - particularly those with "12V" finals -
to get SSB (and data mode) IMD below -50 dBc (-44 dB PEP) as a starting
point or "12V" radios should be limited by their makers to 60-80W where
the IMD is much lower than at 100-120W levels.

For ARRL to have silently watched transmit IMD degrade by nearly 20 dB
in the last 40 years and not raised the issue is unconscionable.

Lest anyone think I'm picking on Elecraft ... the IMD issues are the
same in many solid state amplifiers, they are rated for saturated
conditions which drive up IMD.  Most are significantly less dirty when
operated at 60-75% of rated PEP output unless the designer has built in
a significant amount of negative feedback.  When a 1200W PEP amplifier
has only 8 150W transistors or or a 600 W amplifier has only two 300 W
transistors that's a good sign the amplifier can not possibly be clean
at its rated output.

73,

   ... Joe, W4TV


On Thu, Oct 29, 2015 at 2:58 PM, Jim Brown 
wrote:


According to ARRL measurements, the K3 produces the cleanest CW signal of
any current rig. See my summary of their published data in the following
link

k9yc.com/TXNoise.pdf

See my measurements of my K3 and several other rigs in this link

http://k9yc.com/P3_Spectrum_Measurements.pdf

73, Jim K9YC


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Guy Olinger K2AV

On Thu, Oct 29, 2015 at 2:58 PM, Jim Brown 
wrote:

> According to ARRL measurements, the K3 produces the cleanest CW signal of
> any current rig. See my summary of their published data in the following
> link
>
> k9yc.com/TXNoise.pdf
>
> See my measurements of my K3 and several other rigs in this link
>
> http://k9yc.com/P3_Spectrum_Measurements.pdf
>
> 73, Jim K9YC
>

Any chance you will be able to revise those two documents by adding K3S or
K3/syn3a mod, without removing the existing K3 curves in there? Think that
might put the synthesizer mod in a very appropriate setting.

73, Guy K2AV
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Jim Brown


On Thu,10/29/2015 12:06 PM, frank wrote:

Also, you did not answer my questions.  Maybe I should ask them one at a time.


I thought Wayne answered them quite well, but I'll try to rephrase his 
answers in terms that are easier to understand.


1) Contemporary ham rigs are designed to operate from automotive DC 
voltages as a matter of convenience.


2) The output transistors used in these rigs produce less distortion at 
higher supply voltages.


3) Most rigs are optimized for 13.8 - 14 VDC, and are tested at that 
level by ARRL.


4) Most commercial power supplies marketed to hams are regulated to 13.8 
- 14.5 VDC, and that voltage is internally adjustable.


5) Most rigs will work at lower DC power supply voltages.

6) When operated at lower DC power supply voltage, their distortion will 
increase.


7) When operated above their design output power, distortion will increase.

8) Doing both 6 and 7 will increase distortion even more.

9) Distortion in the K3 and K3S output stage is specified for full power 
output at 13.8 - 14 VDC, and distortion is greatly reduced when run at 
lower power levels.


My own comments:

Distortion causes the most QRM when running high power. Many of the best 
power amps reach full power with drive power in the range of 50-60 W -- 
the KPA500 needs about 28W, my Titans (I have three) need between 
40-60W, depending on condition of the tubes and the operating frequency. 
An ACOM 1010 needs between 50 and 70 watts, again depending on the 
operating frequency.


> This is state of the art?

How much do you want to pay for "state of the art?" How about the 
infamous pentagon $800 hammer?


According to ARRL measurements, the K3 produces the cleanest CW signal 
of any current rig. See my summary of their published data in the 
following link


k9yc.com/TXNoise.pdf

See my measurements of my K3 and several other rigs in this link

http://k9yc.com/P3_Spectrum_Measurements.pdf

73, Jim K9YC

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread frank

On Thu, 29 Oct 2015 07:43:24 -0700
Wayne Burdick  wrote:


> The K3 and K3S, like our other radios, are very popular for Field Day and 
> other applications where a battery might be used. So we provide two ways for 
> you to monitor the supply voltage:
> 
> 1. The CONFIG:BAT MIN menu entry. This sets the voltage at which you will 
> periodically see a BAT LOW warning on the display. 
> 
> 2. Voltage display: Tap DISP and rotate VFO B until you see XX.X VDC. You can 
> also display current drain and PA temperature this way.
> 

Verifying the obvious is sometimes helpful.  Of course the battery voltage is 
going to drop when you are pulling enough current to power a 100 watt 
transceiver.

I was hoping for a more pro-active suggestion to the IMD problem.

My old Drake, tube type, mobile did not have an IMD problem even when run off 
less than 12 volts.  it had a switching supply delivering 700 volts at 200ma to 
the finals.  Today we use switching supplies to deliver 12 volts to finals that 
are not capable of delivering a clean signal at 12 volts.

This is state of the art?

Just because everyone else is building radios that produce dirty signals, does 
that justify doing the same?

Also, you did not answer my questions.  Maybe I should ask them one at a time.

I
> 
> On Oct 29, 2015, at 8:09 AM, frank  wrote:
> 
> > This subject keeps cropping up.  Is this a serious issue ?
> > 
> > I have heard that IMD improves by 10db with a one volt increase in supply 
> > voltage.  Is this really the case or just a measurement error?  10db is a 
> > large difference.  One volt is a small variation.
> > 
> > What is the minimum acceptable IMD?  How linear does the amp need to be?  
> > If 36db is better than 26db is 100db even better or just overkill?
> > 
> > Are other solid state amplifier products similarly effected?
> > 
> > What is the IMD performance of the K3S at 10 watts over a supply voltage 
> > variation from 11 volts to 14.7 volts?  I ask because I believe those ten 
> > watts are generated by Dmos devices as well.  Do these devices only 
> > misbehave with varying supply voltage at higher (100w) power levels and 
> > lower supply voltages?
> > 
> > Should I wait to purchase a K3S until this issue is resolved?  (Assuming 
> > this is a valid issue)
> > 
> > Back in the good old days we used to solve problems.  Today we don't have 
> > problems, just issues.  
> > 
> > -- 
> > Frank - K5DKZ
> > KX3 - 7550
> > PX3 - 1143
> > KXPA100 - 1566
> > __
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft@mailman.qth.net
> > 
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to n...@elecraft.com
> 


-- 
Frank - K5DKZ
KX3 - 7550
PX3 - 1143
KXPA100 - 1566
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Bill Frantz

And 120W over 100W gives you a whopping 0.8dB increase in power. 
Will anyone notice?


I see the "easy to measure" effect in many fields. Anything 
that's easy to measure becomes the only thing to optimize. In 
program language compilers,the speed of the optimized program is 
easy to measure so it is more important than robustness, which 
is hard to measure. In cars, horsepower is easy to measure, so 
it becomes more important than handling. In cameras, its pixels 
over lens quality. In radios, it's power over IMD. etc.


73 Bill AE6JV

On 10/29/15 at 7:41 AM, w3...@embarqmail.com (Don Wilhelm) wrote:

So the thing to do is to run the power supply voltage up to 
near 15 volts (but not above), and do not operate with "all 
knobs to the right".
Many hams seen to want to squeeze all the power output that 
they can from a transceiver, so you will put a cleaner signal 
on the air if you set the power to 100 watts rather than trying 
to squeeze that last 20 extra watts out of an amplifier.


--
Bill Frantz| There are now so many exceptions to the
408-356-8506   | Fourth Amendment that it operates only by
www.pwpconsult.com | accident.  -  William Hugh Murray

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread jim

How about 80 watts instead.

Won't make a noticeable difference on the receive end.

Even better, get rid of all the Yaesu and Icom "Clackers" with their VERY
poor CW performance.  You can have the best class A amplifier in the world,
but garbage in will always equal garbage out.

I am ashamed at our "leaders" at the ARRL for not petitioning the FCC for
better specs.  The technology is there, they all use it in their business
radios that have a better spec.

Oh, I forgot, follow the money and take the advertising monies from these
clackers

Jim
W6AIM

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don
Wilhelm
Sent: Thursday, October 29, 2015 7:41 AM
To: frank; elecraft@mailman.qth.net
Subject: Re: [Elecraft] IMD and supply voltage

Frank,

I think the "issue" is one of some hams wanting to make what is good already
into something better.
If you look closely you should discover that this is a situation common to
*all* 100 watt class amplifiers that are supposed to run on a nominal
'12 volt' supply.  That voltage level is chosen because it is common for
vehicle batteries, so most transceivers are designed around that voltage
- the K3S is just one of those.

Using an increased voltage power supply will drastically reduce the transmit
IMD, and that is true for all those 100 watt class amplifiers.
Bottom line is that I don't think it will be "fixed" in the K3S - I don't
think it can be fixed in any of the 100 watt class solid state amplifiers.

So the thing to do is to run the power supply voltage up to near 15 volts
(but not above), and do not operate with "all knobs to the right".
Many hams seen to want to squeeze all the power output that they can from a
transceiver, so you will put a cleaner signal on the air if you set the
power to 100 watts rather than trying to squeeze that last 20 extra watts
out of an amplifier.

73,
Don W3FPR

On 10/29/2015 11:09 AM, frank wrote:
> This subject keeps cropping up.  Is this a serious issue ?
>
> I have heard that IMD improves by 10db with a one volt increase in supply
voltage.  Is this really the case or just a measurement error?  10db is a
large difference.  One volt is a small variation.
>
> What is the minimum acceptable IMD?  How linear does the amp need to be?
If 36db is better than 26db is 100db even better or just overkill?
>
> Are other solid state amplifier products similarly effected?
>
> What is the IMD performance of the K3S at 10 watts over a supply voltage
variation from 11 volts to 14.7 volts?  I ask because I believe those ten
watts are generated by Dmos devices as well.  Do these devices only
misbehave with varying supply voltage at higher (100w) power levels and
lower supply voltages?
>
> Should I wait to purchase a K3S until this issue is resolved?  (Assuming
this is a valid issue)
>
>

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jbol...@outlook.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread ae4pb

Does that imply we should all adjust our power supplies to output +15VDC?
Will that damage my 2M Rig?
I recently purchased the powerwerx SS-30DV from Elecraft when I purchased my
K3S kit.

Thanks 

Jerry Moore
CDXA, INDEXA, SKCC, Fists
AE4PB, K3S - S.N. 010324
http://www.qrz.com/db/AE4PB
An Amateur is - Considerate, Loyal, Progressive, Friendly, Balanced, and
Patriotic.


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Wayne Burdick

Frank,

All radios that run from an external DC supply (to make them usable with 
emergency power sources, such as a 12-V car battery or solar panel) are subject 
to increasing TX IMD as supply voltage goes down. But such radios are virtually 
all specified (by the manufacturer) and tested (in QST reviews, for example) at 
a standard bench supply voltage of about 14 V. 

If you're running from lower voltages, such as from a depleted 12 V car 
battery, the radio is not likely to put out full power on all bands. This 
effect will vary with band, load impedance, and the actual voltage. You could 
simply crank the power all the way up and accept whatever TX IMD results from 
this. Instead, we recommend reducing power manually if you know the voltage is 
low.

The K3 and K3S, like our other radios, are very popular for Field Day and other 
applications where a battery might be used. So we provide two ways for you to 
monitor the supply voltage:

1. The CONFIG:BAT MIN menu entry. This sets the voltage at which you will 
periodically see a BAT LOW warning on the display. 

2. Voltage display: Tap DISP and rotate VFO B until you see XX.X VDC. You can 
also display current drain and PA temperature this way.

73,
Wayne
N6KR

On Oct 29, 2015, at 8:09 AM, frank  wrote:

> This subject keeps cropping up.  Is this a serious issue ?
> 
> I have heard that IMD improves by 10db with a one volt increase in supply 
> voltage.  Is this really the case or just a measurement error?  10db is a 
> large difference.  One volt is a small variation.
> 
> What is the minimum acceptable IMD?  How linear does the amp need to be?  If 
> 36db is better than 26db is 100db even better or just overkill?
> 
> Are other solid state amplifier products similarly effected?
> 
> What is the IMD performance of the K3S at 10 watts over a supply voltage 
> variation from 11 volts to 14.7 volts?  I ask because I believe those ten 
> watts are generated by Dmos devices as well.  Do these devices only misbehave 
> with varying supply voltage at higher (100w) power levels and lower supply 
> voltages?
> 
> Should I wait to purchase a K3S until this issue is resolved?  (Assuming this 
> is a valid issue)
> 
> Back in the good old days we used to solve problems.  Today we don't have 
> problems, just issues.  
> 
> -- 
> Frank - K5DKZ
> KX3 - 7550
> PX3 - 1143
> KXPA100 - 1566
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to n...@elecraft.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] IMD and supply voltage

2015-10-29 Thread Don Wilhelm


Frank,

I think the "issue" is one of some hams wanting to make what is good 
already into something better.
If you look closely you should discover that this is a situation common 
to *all* 100 watt class amplifiers that are supposed to run on a nominal 
'12 volt' supply.  That voltage level is chosen because it is common for 
vehicle batteries, so most transceivers are designed around that voltage 
- the K3S is just one of those.


Using an increased voltage power supply will drastically reduce the 
transmit IMD, and that is true for all those 100 watt class amplifiers.
Bottom line is that I don't think it will be "fixed" in the K3S - I 
don't think it can be fixed in any of the 100 watt class solid state 
amplifiers.


So the thing to do is to run the power supply voltage up to near 15 
volts (but not above), and do not operate with "all knobs to the right".
Many hams seen to want to squeeze all the power output that they can 
from a transceiver, so you will put a cleaner signal on the air if you 
set the power to 100 watts rather than trying to squeeze that last 20 
extra watts out of an amplifier.


73,
Don W3FPR

On 10/29/2015 11:09 AM, frank wrote:

This subject keeps cropping up.  Is this a serious issue ?

I have heard that IMD improves by 10db with a one volt increase in supply 
voltage.  Is this really the case or just a measurement error?  10db is a large 
difference.  One volt is a small variation.

What is the minimum acceptable IMD?  How linear does the amp need to be?  If 
36db is better than 26db is 100db even better or just overkill?

Are other solid state amplifier products similarly effected?

What is the IMD performance of the K3S at 10 watts over a supply voltage 
variation from 11 volts to 14.7 volts?  I ask because I believe those ten watts 
are generated by Dmos devices as well.  Do these devices only misbehave with 
varying supply voltage at higher (100w) power levels and lower supply voltages?

Should I wait to purchase a K3S until this issue is resolved?  (Assuming this 
is a valid issue)




__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

[Elecraft] IMD and supply voltage

2015-10-29 Thread frank

This subject keeps cropping up.  Is this a serious issue ?

I have heard that IMD improves by 10db with a one volt increase in supply 
voltage.  Is this really the case or just a measurement error?  10db is a large 
difference.  One volt is a small variation.

What is the minimum acceptable IMD?  How linear does the amp need to be?  If 
36db is better than 26db is 100db even better or just overkill?

Are other solid state amplifier products similarly effected?

What is the IMD performance of the K3S at 10 watts over a supply voltage 
variation from 11 volts to 14.7 volts?  I ask because I believe those ten watts 
are generated by Dmos devices as well.  Do these devices only misbehave with 
varying supply voltage at higher (100w) power levels and lower supply voltages?

Should I wait to purchase a K3S until this issue is resolved?  (Assuming this 
is a valid issue)

Back in the good old days we used to solve problems.  Today we don't have 
problems, just issues.  

-- 
Frank - K5DKZ
KX3 - 7550
PX3 - 1143
KXPA100 - 1566
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

37 matches

Mail list logo