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KPA-200

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rfenabled

KPA-200

What would the K3 be like if one could order an optional plug in module to replace the 100W PA with a 200W PA?

Just a thought...maybe I didn't get quite enough sleep

Gary
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AC7AC

Re: KPA-200

CONTENTS DELETED

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W7GJ, Lance

Re: KPA-200

In reply to this post by rfenabled

[hidden email] wrote:

> What would the K3 be like if one could order an optional plug in module to replace the 100W PA with a 200W PA?
>
> Just a thought...maybe I didn't get quite enough sleep
>
> Gary
> Sent via BlackBerry® from Telstra
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>

I also would love that, Gary....but I don't think it is technically possible for
them, at least that is what they told me at Dayton previously :-( VY 73, Lance

--
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT 59834 USA
QTH: DN27UB
TEL: (406) 626-5728
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815

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David Gilbert

Re: KPA-200

In reply to this post by AC7AC

I think it all depends upon how you operate.

About two years ago I put together some audio files to determine how
much difference a couple of db would make for readability, as at the
time I was trying to decide between a couple of different antenna
options. I generated some CW using CW Player, a free text-to-audio
application, and then I mixed that with some 80m background noise I had
recorded. I varied the relative signal-to-noise level in one db
increments relative to to the noise until I got below the noise level.

At the noise level, I had to work pretty hard to convince myself that I
could hear the difference that one db would make. Two db was
noticeable, but just barely. Three db was definitely noticeable and in
my opinion could easily make the difference between making a weak signal
DX contact or not. I think I still have the audio files around
somewhere if anyone wants a copy.

However, do I think it makes sense to jam a 200 watt amp into the K3?
Nope. First off, I doubt it makes sense to double the heat dissipation
inside such a small rig. Secondly, 3 db more power out doesn't have the
same utility as three db from the antenna, where it also benefits
reception (I did buy the more expensive antenna, by the way). Thirdly,
my testing indicated that even at signals as low as only 10 db above the
noise level, a 3 db difference was barely noticeable. If you feel the
need to be heard, buy a real amp and give yourself a couple of S-units
instead of a couple of db.

73,
Dave AB7E

Ron D'Eau Claire wrote:

> IMX, it would be an undetectable change in signal strength under almost any
> conditions.
>
> Over the years most engineers working in HF radio systems have found that
> the minimum discernable change in a signal is about 3 dB (2:1 change in
> power) under "ideal" conditions. That's 3 times greater than the 'standard'
> for audio lab work, but what is found in practice given typical background
> noise, minimal QSB, etc. on an HF signal.
>
> You can test this "on the air" very easily. Just hook up with someone in a
> normal QSO and then cut your power in half and see if they notice any
> difference. Don't tell them what you're testing, just that you are making a
> change, and see if anyone can tell you what you changed.
>
> If they're looking at the S-meter on one of those absurd rigs that jumps 1
> or 2 S-units for every 2 dB or so of signal change, they'll see something if
> you're close enough for a rock-solid signal, but they're not likely to hear
> it.
>
> I don't normally get excited about any major change that doesn't give me a
> 10:1 (10 dB) improvement in power.
>
> Now, let's not confuse that with having an efficient station. As any QRP
> enthusiast (or smart Ham at any power) will tell you, a dB here and a dB
> there eventually adds to a significant change in signal strength. But the
> cost/benefits ratio of doubling the power compared to the same ratio going
> to the "legal limit" usually makes such a small change a bad investment.
>
> Ron AC7AC
>
>
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Fred Atchley

Re: KPA-200

In reply to this post by rfenabled

Actually Gary, KPA-200 sounds like a good idea. I like contesting and prefer
low power. The problem is that different contests define "low power" as 100,
150 or 200 W. It would be nice to optimize low power for any given contest.
BTW, I wonder if the KAT3 would also need to be replaced. 73, Fred

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PA5MW

Re: KPA-200

In reply to this post by David Gilbert

Dave,

I performed similar tests using a Marconi signal generator in the following test configurations:

1) static benchmark test: generator directly coupled to 144Mhz receiver
2) live on the air tests: smal antenne coupled to generator, receiver uses outdoor 144Mhz antenna. Test was performed with outdoor antenna aimed at a quiet direction.

My results between hearing the weak signal in the noise yes/no:

static benchmark setup: 1.8 dB
Live on the air setup: 2.2-2.5 dB

Same happens when I insert the DCI 4-pole 144 bandfilter, which has 0.8dB insertion loss; never ever heard any difference in copying weak signals.

These results and some 15 years of trying various pre amps in many situations, made me decide to forget about this whole pre-amp hype (I never did EME, so cannot decide on that) on VHF.

73 Mark, PA5MW

>
> At the noise level, I had to work pretty hard to convince myself that
> I
> could hear the difference that one db would make. Two db was
> noticeable, but just barely. Three db was definitely noticeable and
> in
> my opinion could easily make the difference between making a weak
> signal
> DX contact or not.
>
> 73,
> Dave AB7E

Darwin, Keith

Re: KPA-200

In reply to this post by Fred Atchley

I agree that 200 watts inside the K3 isn't a good idea (heat) but having
an external (300-400 watt?) amp that could be driven by 10 watts of
input (key point here!) would be sweet!

This amp could be used by all the Elecraft rigs, not just the K3. For
contests turn it up to the low power limit per the rules. On 30m, run
full power and be a big gun. I assume a lower power amp (1/2 KW) would
be considerably cheaper to build & buy.

- Keith N1AS -
- K3 711 -

-----Original Message-----
From: Fred Atchley
Subject: Re: [Elecraft] KPA-200

Actually Gary, KPA-200 sounds like a good idea. I like contesting and
prefer low power. The problem is that different contests define "low
power" as 100, 150 or 200 W. It would be nice to optimize low power for
any given contest.
BTW, I wonder if the KAT3 would also need to be replaced. 73, Fred

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Craig Smith

Re: KPA-200

I'm with you on this one, Keith! I'm a low power CW contester and
would surely enjoy using the 150 or 200 W power limit when appropriate
instead of accepting the db or so of loss with my 100W K3. I have NO
interest in running a KW, however, so high power amps have no appeal
here. A small amp with internal power supply with 200W or more
capability would be quite interesting. For my purposes it wouldn't
even need to be linear. As someone else pointed out, class C, D or E
could make for an interesting design!

73 Craig AC0DS

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Eric Swartz - WA6HHQ

Re: KPA-200

Administrator

In reply to this post by Darwin, Keith

We do not see 200W inside the K3 any time soon. The heat, current and
other issues make this difficult.

73, Eric WA6HHQ
Elecraft List Moderator, among other things :-)

_..._

Darwin, Keith wrote:

> I agree that 200 watts inside the K3 isn't a good idea (heat) but having
> an external (300-400 watt?) amp that could be driven by 10 watts of
> input (key point here!) would be sweet!
>
> This amp could be used by all the Elecraft rigs, not just the K3. For
> contests turn it up to the low power limit per the rules. On 30m, run
> full power and be a big gun. I assume a lower power amp (1/2 KW) would
> be considerably cheaper to build & buy.
>
> - Keith N1AS -
> - K3 711 -
>
> -----Original Message-----
> From: Fred Atchley
> Subject: Re: [Elecraft] KPA-200
>
> Actually Gary, KPA-200 sounds like a good idea. I like contesting and
> prefer low power. The problem is that different contests define "low
> power" as 100, 150 or 200 W. It would be nice to optimize low power for
> any given contest.
> BTW, I wonder if the KAT3 would also need to be replaced. 73, Fred
>
> ______________________________________________________________
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Matt Palmer-4

Re: KPA-200

a external 200-400 watt amp is a fairly trivial design, if you want
one order some parts and get building. You could do this with a couple
813's for pretty low cost, or solid state for a bit more money. I'm
surprised how many people sit on their rear end and complain about
this or that product not existing, and how elecraft should design one
for them. Start acting like hams and try rolling your own, you have
complete control over the feature set you want then. If you are
unwilling to do this, I think you have no business clogging the
reflector with your criticisms and wish lists, why not keep the posts
on topic to actual elecraft products, their building, and
troubleshooting.

/end rant.

Matt
W8ESE
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Fred Atchley

Re: KPA-200

In reply to this post by rfenabled

Eric, the posts on this thread by Gary, Keith and me are positive with
regard to Elecraft, so please do not consider them as criticisms in any way.
I've been a Ham since 1957 and Elecraft is the best thing to happen since
807's. Thanks for a great reflector. 73, Fred

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AC7AC

Re: KPA-200

In reply to this post by Matt Palmer-4

CONTENTS DELETED

The author has deleted this message.

w4nhj

Re: KPA-200

In reply to this post by Matt Palmer-4

I like to homebrew some of my equipment, all, if I could produce equipment
as good as Elecraft's and some of the other well known vendors. Building an
amplifier is one area I believe the ham can come close to building a product
as good as the average vendor's. If you are talking about tube amps, I
think the ham can do a better job then many of the vendor amps. If you want
a fully integrated amp for the K2 and/or K3 that will be a little harder and
you might want to wait for Elecraft.

Frank - W4NHJ

----- Original Message -----
From: "Matt Palmer" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, May 19, 2009 10:10 AM
Subject: Re: [Elecraft] KPA-200

>a external 200-400 watt amp is a fairly trivial design, if you want
> one order some parts and get building. You could do this with a couple
> 813's for pretty low cost, or solid state for a bit more money. I'm
> surprised how many people sit on their rear end and complain about
> this or that product not existing, and how elecraft should design one
> for them. Start acting like hams and try rolling your own, you have
> complete control over the feature set you want then. If you are
> unwilling to do this, I think you have no business clogging the
> reflector with your criticisms and wish lists, why not keep the posts
> on topic to actual elecraft products, their building, and
> troubleshooting.
>
>
> /end rant.
>
> Matt
> W8ESE
> ______________________________________________________________
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Ed Muns, W0YK

Re: KPA-200

In reply to this post by Eric Swartz - WA6HHQ

On the contest side, all the CQWW and CQ WPX contests for all three modes
(CW, Phone and RTTY) have a 100 watt limit for the Low Power category. So
do the NCJ NAQP and Sprint contests, twelve total each year. The reason for
this is two-fold. First, 100 watts covers the majority of HF transceivers
and second, it is a larger distinction from High Power. If someone wants to
run more than 100 watts, they can enter the High Power category.
Unfortunately, ARRL still has a 150 watt PEP limit on their Low Power
category. However, the effective difference between 100 and 150 watts is
negligible in reality and many contesters, including the serious ones, don't
worry about running 100 watts in ARRL contests.

Ed - W0YK

Eric, WA6HHQ replied:

> We do not see 200W inside the K3 any time soon. The heat,
> current and other issues make this difficult.
>
> Darwin, Keith wrote:
> > I agree that 200 watts inside the K3 isn't a good idea (heat) but
> > having an external (300-400 watt?) amp that could be driven by 10
> > watts of input (key point here!) would be sweet!
> >
> > This amp could be used by all the Elecraft rigs, not just
> the K3. For
> > contests turn it up to the low power limit per the rules.
> On 30m, run
> > full power and be a big gun. I assume a lower power amp (1/2 KW)
> > would be considerably cheaper to build & buy.
>
> Fred Atchley replied:
> > Actually Gary, KPA-200 sounds like a good idea. I like
> contesting and
> > prefer low power. The problem is that different contests
> define "low
> > power" as 100, 150 or 200 W. It would be nice to optimize low power
> > for any given contest.
> > BTW, I wonder if the KAT3 would also need to be replaced. 73, Fred

Ignacy

Re: KPA-200

In reply to this post by Darwin, Keith

I worked someone using K2/10 with ALS600 modified for low power (by cutting some input resistors). He said he was getting > 400W on most bands.
Ignacy

<quote author="Darwin, Keith">
I agree that 200 watts inside the K3 isn't a good idea (heat) but having
an external (300-400 watt?) amp that could be driven by 10 watts of
input (key point here!) would be sweet!

Darwin, Keith

Re: KPA-200

In reply to this post by AC7AC

---------------------------
Matt, W8ESE, wrote:

a external 200-400 watt amp is a fairly trivial design, if you want one
order some parts and get building. You could do this with a couple 813's
for pretty low cost, or solid state for a bit more money.

---------------------------------------

Ron, AC7AC, replied:

*snip*

For some of us, the first and most interesting part of Ham radio is the
challenge of building and modifying gear.

For others, the most interesting part of Ham radio is snagging new DX or
hitting a bigger contest score. Many of these Hams are looking for "plug
'n play" solutions. They have little or no interest in building.

============================================

While Matt has a point, I'm more inclined to "hang with Ron". There is
significant variation in interests. I've never been that interested in
building. I wasn't back in 1977, and am not today. The K2 I build was
lots of fun, but I've been there / done that. Yes, I am a ham but that
doesn't mean I'm an electronics hobbyist. I'm a CW hobbyist. I like
CW, I like sending code with bugs & straight keys and the Elecraft gear
is my chosen vehicle. I don't operate SSB, FM, Packet, VHF, UHF.
Others do. Interests vary.

I don't have time to build. I barely have time to be on the air at all.
Full time job, part time job, Church duties, volunteering at the school,
mowing the grass (2.5 acres) ... You get the idea.

And, yes, I absolutely feel that discussing possible future amps and my
desires for them is completely on-topic since Elecraft is interested in
producing an amp. My views on which Pellet Rifles I prefer or why I use
Canon rather than Nikon (http://DarwinPhotoVT.com) would be off topic so
I won't post about those.

73!

- Keith N1AS -
- K3 711 -
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Eric Swartz - WA6HHQ

Re: KPA-200

Administrator

In reply to this post by Fred Atchley

Absolutely! :-) We always appreciate constructive feedback and suggestions.

All that we ask is that people avoid posting on a high # of postings
topic unless they have substantive info to add.

73, Eric WA6HHQ

Fred Atchley wrote:
> Eric, the posts on this thread by Gary, Keith and me are positive with
> regard to Elecraft, so please do not consider them as criticisms in any way.
> I've been a Ham since 1957 and Elecraft is the best thing to happen since
> 807's. Thanks for a great reflector. 73, Fred
>
>
>
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Jim Brown-10

Re: KPA-200

In reply to this post by PA5MW

On Tue, 19 May 2009 08:30:26 +0200, [hidden email] wrote:

>My results between hearing the weak signal in the noise yes/no:

>static benchmark setup: 1.8 dB
>Live on the air setup: 2.2-2.5 dB

Several years ago, N6ZFO published some statistical analysis of
Sweepstakes score suggesting that a 1 dB increase in transmitted
signal strength is good for about a 2.6% increase in an operator's
score. More than once, I've unsuccessfrully called a weak station
with 800-1,000 watts, then pushed the amp up to legal power and
worked him. It depends on QRM and QRN on the other end, and
sometimes whether his RX antenna is pointed in your direction. I
work a lot of stations that I wouldn't have heard without my
Beverages. And lots of guys are stuck with S8 noise levels.

73,

Jim Brown K9YC

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w7aqk

Re: KPA-200

In reply to this post by AC7AC

I suppose 813's are still available, but I don't see them
listed very often. I do, however, see 811's a lot.
Wouldn't a couple of those work for that kind of power
range? Maybe it would take 3, but they seem to be readily
available, and pretty inexpensive.

By the way, at the swap area at Dayton this year I saw an
old Heath HA-14 (hadn't seen one of those for a while!). I
think it uses 811's or 572B's--a pair--laying sideways. The
guy was pretty proud of it though, as he wanted $900 for it!
I guess they are rare enough that he was serious.

Dave W7AQK

----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, May 19, 2009 7:52 AM
Subject: Re: [Elecraft] KPA-200

> Matt, W8ESE, wrote:
>
> a external 200-400 watt amp is a fairly trivial design, if
> you want
> one order some parts and get building. You could do this
> with a couple
> 813's for pretty low cost, or solid state for a bit more
> money.
>
> ---------------------------------------
>
> 813s! I'm with you Matt!
>
> I have to constantly remind myself that Ham radio has
> changed.
>
> For some of us, the first and most interesting part of Ham
> radio is the
> challenge of building and modifying gear.
>
> For others, the most interesting part of Ham radio is
> snagging new DX or
> hitting a bigger contest score. Many of these Hams are
> looking for "plug 'n
> play" solutions. They have little or no interest in
> building.
>
> Of course most of us are a little bit of both, but the
> swing is definitely
> toward the "plug 'n play" group here on the Elecraft
> reflector.
>
> We're all Hams, but becoming more disparate in our
> interests as times
> change. I sometimes feel like I'm bouncing back and forth
> across a warp in
> space-time, reading here about people drooling over a
> $13,000 legal-limit
> amplifier or a better feeling knob, then finding in my
> in-box other e-mails
> about Hams who are still cobbling their receivers and
> transmitters together
> from scrapped 1960's TV sets and building variable
> condensers out of
> discarded food cans.
>
> Ron AC7AC
>
> ______________________________________________________________
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Steve Ward

Re: KPA-200

In reply to this post by rfenabled

Fred Atchley writes:

>Actually Gary, KPA-200 sounds like a good idea. I like contesting and prefer
>low power. The problem is that different contests define "low power" as 100,
>150 or 200 W. It would be nice to optimize low power for any given contest.
>BTW, I wonder if the KAT3 would also need to be replaced. 73, Fred

Seems to me the biggest issue would be (DC) power. Most of the rigs that can do 200w internally seem to come with their own custom power supplies that give 24 or 48 VDC. Running 200w on 13.8VDC requires a LOT of amperes and is probably not practical.

73,

Steve
AD7OG
K3 #1544

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