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100 Watts or 500 Watts

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Frank MacDonell

100 Watts or 500 Watts

I own a K3/10 with ATU and would like to upgrade power. The question
is do I go with the 100w PA option or wait for the KPA500. Any and all
comments are most welcome. Thanks in advance and Merry Christmas to
all.

--
Frank KD8FIP
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Don Wilhelm-4

Re: 100 Watts or 500 Watts

Frank,

If you think you want 500 watts out, you will have to install the KPA3
(100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
full output - you may be able to get somewhere betwen 200 and 300 watts
out of it.

73,
Don W3FPR

On 12/20/2010 1:39 PM, Frank MacDonell wrote:
> I own a K3/10 with ATU and would like to upgrade power. The question
> is do I go with the 100w PA option or wait for the KPA500. Any and all
> comments are most welcome. Thanks in advance and Merry Christmas to
> all.
>
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Able2fly

Re: 100 Watts or 500 Watts

Why wouldn't Elecraft design the KPA500 to be driven to its rated output by a K3/10 ?

Bill K3UJ

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Subject: Re: [Elecraft] 100 Watts or 500 Watts

Frank,
If you think you want 500 watts out, you will have to install the KPA3
100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
ull output - you may be able to get somewhere betwen 200 and 300 watts
ut of it.
73,
on W3FPR

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Don Wilhelm-4

Re: 100 Watts or 500 Watts

Bill,

It is not an Elecraft choice.
While you could do that as an individual, commercial products (sold in
the US) must meet the FCC requirement of a 15 dB maximum gain That
limits the maximum power gain to a factor of 31.62 - 10 watts in gives
316.2 watts (at the most) output.

73,
Don W3FPR

On 12/20/2010 3:23 PM, [hidden email] wrote:

> Why wouldn't Elecraft design the KPA500 to be driven to its rated output by a K3/10 ?
>
> Bill K3UJ
>
>
>
>
>
>
> -----Original Message-----
> From: Don Wilhelm<[hidden email]>
> Subject: Re: [Elecraft] 100 Watts or 500 Watts
>
>
> Frank,
> If you think you want 500 watts out, you will have to install the KPA3
> 100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
> ull output - you may be able to get somewhere betwen 200 and 300 watts
> ut of it.
> 73,
> on W3FPR
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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>

Rick Dettinger-3

Re: 100 Watts or 500 Watts

In reply to this post by Don Wilhelm-4

But going directly from the K3/10 to the KPA500 might be a good way
for those unhappy with the SSB transmit quality of the KPA3 to get a
very clean signal since the KPA500 uses 70 volt devices for the final
amplifiers. Plus a 3 db. gain over the KPA3. At a cost, of course.

73,
Rick Dettinger K7MW

> Frank,
>
> If you think you want 500 watts out, you will have to install the KPA3
> (100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
> full output - you may be able to get somewhere betwen 200 and 300
> watts
> out of it.
>
> 73,
> Don W3FPR
>

Rick Dettinger-3

Re: 100 Watts or 500 Watts

In reply to this post by Able2fly

Not legal in the United States. 15 db gain is the max allowed. The
hams get punished for the illegal activity of others.

73,

Rick Dettinger K7MW

>
> Why wouldn't Elecraft design the KPA500 to be driven to its rated
> output by a K3/10 ?
>
> Bill K3UJ
>
>
>
>
>
> Please help support this email list: http://www.qsl.net/donate.html

ab2tc

Re: 100 Watts or 500 Watts

In reply to this post by Rick Dettinger-3

Hi,

Not so sure. That would require the 12W (pre)amp in the K3 to run full tilt. I seem to remember from the QST review of the K3/10 that it wasn't super clean at full power either. It's well known that both these amps get significantly cleaner when run at 50% or less which is what they would do driving the KPA500 to full power.

AB2TC - Knut

Rick Dettinger-3 wrote

But going directly from the K3/10 to the KPA500 might be a good way
for those unhappy with the SSB transmit quality of the KPA3 to get a
very clean signal since the KPA500 uses 70 volt devices for the final
amplifiers. Plus a 3 db. gain over the KPA3. At a cost, of course.

73,
Rick Dettinger K7MW

<snip>

Dale Parfitt-3

Re: 100 Watts or 500 Watts

In reply to this post by Don Wilhelm-4

Hi Don,
I use my SPE Expert 1K-FA with my barefoot K3. I get around 900Wout on HF
and about 500W on 6M. It's a great combination as the K3 talks to the SPE
and everything is transparent including the SPE's built in autotuner.
The SPE display reports over 18dB gain. It has been type accepted and sold
by SteppIR.

Dale W4OP

> Bill,
>
> It is not an Elecraft choice.
> While you could do that as an individual, commercial products (sold in
> the US) must meet the FCC requirement of a 15 dB maximum gain That
> limits the maximum power gain to a factor of 31.62 - 10 watts in gives
> 316.2 watts (at the most) output.
>
> 73,
> Don W3FPR
>
> On 12/20/2010 3:23 PM, [hidden email] wrote:
>> Why wouldn't Elecraft design the KPA500 to be driven to its rated output
>> by a K3/10 ?
>>
>> Bill K3UJ
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: Don Wilhelm<[hidden email]>
>> Subject: Re: [Elecraft] 100 Watts or 500 Watts
>>
>>
>> Frank,
>> If you think you want 500 watts out, you will have to install the KPA3
>> 100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
>> ull output - you may be able to get somewhere betwen 200 and 300 watts
>> ut of it.
>> 73,
>> on W3FPR
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
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--------------------------------------------------------------------------------

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Don Wilhelm-4

Re: 100 Watts or 500 Watts

Dale,

I am not going to question the legality of the 18 dB gain you are
getting on that SPE nor what the SPE documents filed with the FCC say
about the maximum gain - Mu understanding is only that the FCC says 15
dB is the maximum, and I expect Elecraft will comply with that. What
other companies do is not a concern of mine - I am not in any
enforcement role.

73,
Don W3FPR

On 12/20/2010 3:49 PM, Dale Parfitt wrote:
> Hi Don,
> I use my SPE Expert 1K-FA with my barefoot K3. I get around 900Wout on HF
> and about 500W on 6M. It's a great combination as the K3 talks to the SPE
> and everything is transparent including the SPE's built in autotuner.
> The SPE display reports over 18dB gain. It has been type accepted and sold
> by SteppIR.
>
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Byron N6NUL

Re: 100 Watts or 500 Watts

>From my copy of the ARRL FCC Rules and Regulations for the Amateur
Radio Service, parts 97 and 47 of the Cod of Federal Regulations,
2007:

97.317 Standards for certification of external RF power amplifiers
(a) To receive a grant of certification, the amplifier must:

(2) Not be capable of amplifying the input RF power (driving signal)
by more than 15 dB gain. Gain is defined as the ratio of the input RF
power to the output RF power of the amplifier where both power
measurements are expressed in peak envelope power or mean power.

73, Byron N6NUL

On Mon, Dec 20, 2010 at 1:20 PM, Don Wilhelm <[hidden email]> wrote:
> My understanding is only that the FCC says 15
> dB is the maximum, and I expect Elecraft will comply with that.
--
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org
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k.igor

Re: 100 Watts or 500 Watts

In reply to this post by Don Wilhelm-4

Is there any technical merit behind FCC's 15dB amp gain limitation? I saw
commercial RF amplifiers with gains up to 30dB, obviously approved by FCC. I
could understand the limitation for tube amplifiers, the characteristics of
some amp tubes would make high gain unstable. But for solid state amplifiers
the limitation looks strange to say the least. Maybe it's time to ask FCC to
reconsider this. Any ARRL lawyers out there?
73,
Igor, N1YX

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Monday, December 20, 2010 3:31 PM
To: [hidden email]
Cc: [hidden email]; [hidden email]
Subject: Re: [Elecraft] 100 Watts or 500 Watts

Bill,

It is not an Elecraft choice.
While you could do that as an individual, commercial products (sold in
the US) must meet the FCC requirement of a 15 dB maximum gain That
limits the maximum power gain to a factor of 31.62 - 10 watts in gives
316.2 watts (at the most) output.

73,
Don W3FPR

On 12/20/2010 3:23 PM, [hidden email] wrote:
> Why wouldn't Elecraft design the KPA500 to be driven to its rated output
by a K3/10 ?

>
> Bill K3UJ
>
>
>
>
>
>
> -----Original Message-----
> From: Don Wilhelm<[hidden email]>
> Subject: Re: [Elecraft] 100 Watts or 500 Watts
>
>
> Frank,
> If you think you want 500 watts out, you will have to install the KPA3
> 100 watts) anyway. The K3/10 will not be able to drive the KPA500 to
> ull output - you may be able to get somewhere betwen 200 and 300 watts
> ut of it.
> 73,
> on W3FPR
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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Dave KQ3T

Re: 100 Watts or 500 Watts

Igor,

I think, at least in part, the regulation is intended to make amateur
amplifiers less attractive to users of the Citizen's Radio Service.

Rather than being able to go from 5W to 1000+W with a single, relatively
inexpensive amp, an amp to get from 5W to ~100W is needed in order to
drive the KW amp.. And except for Elecraft, I'm not aware of any other
5->100W amplifiers.

73,
Dave KQ3T

On 12/22/2010 1:29 AM, Igor Kosvin wrote:
> Is there any technical merit behind FCC's 15dB amp gain limitation? I saw
> commercial RF amplifiers with gains up to 30dB, obviously approved by FCC. I
> could understand the limitation for tube amplifiers, the characteristics of
> some amp tubes would make high gain unstable. But for solid state amplifiers
> the limitation looks strange to say the least. Maybe it's time to ask FCC to
> reconsider this. Any ARRL lawyers out there?
> 73,
> Igor, N1YX
>

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AC7AC

Re: 100 Watts or 500 Watts

CONTENTS DELETED

The author has deleted this message.

Vic K2VCO

Re: 100 Watts or 500 Watts

I just finished building a grid-driven amplifier using two 813 tubes. With a 3 db
attenuator at the input, it requires between 16 and 40 watts of drive on 160 through 10
meters respectively, for 800 watts output (only 700 on 10). Without the attenuator, it
would need 8 - 20 watts drive.

And this is a class-C amplifier designed for CW only! If it were a class B or AB linear,
the drive requirement would be even lower.

Grounded-grid is not the only way to design a tube amplifier. Although a traditional
grid-driven circuit is a little more complicated, it's one way to get more gain.

I am going to put some pictures and schematics on my web site soon, not that I think
anyone will want to duplicate it!

On 12/22/2010 7:50 AM, Ron D'Eau Claire wrote:

> Even the Elecraft 100 watt amps are integrated with either the K2 or K3
> control logic so they cannot be used as a stand-alone amplifier with other
> transmitters.
>
> The only reason I have ever seen from the FCC for the amplifier
> certification and 15 dB gain limitation is to discourage the CB
> 'bootleggers'. Certainly building a stable, clean amplifier that would take
> even a few milliwatts to 1000+ watts is a straightforward design exercise.
> There's no real problem with using more than one stage of gain if there was
> no 15 dB limit on the system gain.
>
> Ron AC7AC

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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Dale Parfitt-3

Re: 100 Watts or 500 Watts

Hi Vic,
Dave Ishmael has a single 813 amplifeir in this month's Electric Radio.
Please do publish your amp for all of us to look at. I still have an 813
and socket I have had since I was a kid- maybe it's time to build an amp for
my Atlas 350XL.

Dale W4OP
----- Original Message -----
From: "Vic K2VCO" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, December 22, 2010 11:14 AM
Subject: Re: [Elecraft] 100 Watts or 500 Watts

>I just finished building a grid-driven amplifier using two 813 tubes. With
>a 3 db
> attenuator at the input, it requires between 16 and 40 watts of drive on
> 160 through 10
> meters respectively, for 800 watts output (only 700 on 10). Without the
> attenuator, it
> would need 8 - 20 watts drive.
>
> And this is a class-C amplifier designed for CW only! If it were a class B
> or AB linear,
> the drive requirement would be even lower.
>
> Grounded-grid is not the only way to design a tube amplifier. Although a
> traditional
> grid-driven circuit is a little more complicated, it's one way to get more
> gain.
>
> I am going to put some pictures and schematics on my web site soon, not
> that I think
> anyone will want to duplicate it!
>
> On 12/22/2010 7:50 AM, Ron D'Eau Claire wrote:
>> Even the Elecraft 100 watt amps are integrated with either the K2 or K3
>> control logic so they cannot be used as a stand-alone amplifier with
>> other
>> transmitters.
>>
>> The only reason I have ever seen from the FCC for the amplifier
>> certification and 15 dB gain limitation is to discourage the CB
>> 'bootleggers'. Certainly building a stable, clean amplifier that would
>> take
>> even a few milliwatts to 1000+ watts is a straightforward design
>> exercise.
>> There's no real problem with using more than one stage of gain if there
>> was
>> no 15 dB limit on the system gain.
>>
>> Ron AC7AC
>
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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Version: 9.0.872 / Virus Database: 271.1.1/3331 - Release Date: 12/22/10
02:34:00

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John Ragle

Re: 100 Watts or 500 Watts

On 12/22/2010 11:30 AM, a lister wrote:

Grounded-grid is not the only way to design a tube amplifier. Although a
traditional grid-driven circuit is a little more complicated, it's one way to get more gain.

Amen to that. When I was little, "grounded grid" was vaunted as the way to use triodes without needing neutralization, even though one took a real hit on gain. Unfortunately, the old-time big amps that use/used several triodes in parallel in grounded grid still have a tendency to "take off."

The 813 and the various Eimac ceramic tetrodes are wonderful tubes, and if one can go high voltage low current, they are excellent performers. Again, when I was young, solid state devices wouldn't function in the VHF/UHF region, and the 4CXnnn series were practically a necessity. Need I refer to the beautiful amps vended by one of the early moonbounce guys?

I for one would like to see designs using these tubes. Not all of us need linear/linearized amps.

John Ragle -- W1ZI

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Vic K2VCO

Re: 100 Watts or 500 Watts

In reply to this post by Dale Parfitt-3

For linear purposes, 813's work in grounded grid with the screen tied to the control grid
and grounded. You can also make a class AB1 amplifier with a 'grid circuit' consisting of
a big 50-ohm dummy load. And then there is the G2DAF circuit, in which the screen voltage
is derived fom the drive -- but I only recommend this one for SSB if you have a means for
checking IMD; it may require some careful adjustment.

I'll put up the report on my amp soon. I need to redraw the schematics which are a
horrible mess at present.

On 12/22/2010 8:30 AM, Dale Parfitt wrote:

> Hi Vic,
> Dave Ishmael has a single 813 amplifeir in this month's Electric Radio. Please do publish
> your amp for all of us to look at. I still have an 813 and socket I have had since I was a
> kid- maybe it's time to build an amp for my Atlas 350XL.
>
> Dale W4OP
> ----- Original Message ----- From: "Vic K2VCO" <[hidden email]>
> To: <[hidden email]>
> Sent: Wednesday, December 22, 2010 11:14 AM
> Subject: Re: [Elecraft] 100 Watts or 500 Watts
>
>
>> I just finished building a grid-driven amplifier using two 813 tubes. With a 3 db
>> attenuator at the input, it requires between 16 and 40 watts of drive on 160 through 10
>> meters respectively, for 800 watts output (only 700 on 10). Without the attenuator, it
>> would need 8 - 20 watts drive.
>>
>> And this is a class-C amplifier designed for CW only! If it were a class B or AB linear,
>> the drive requirement would be even lower.
>>
>> Grounded-grid is not the only way to design a tube amplifier. Although a traditional
>> grid-driven circuit is a little more complicated, it's one way to get more gain.
>>
>> I am going to put some pictures and schematics on my web site soon, not that I think
>> anyone will want to duplicate it!
>>
>> On 12/22/2010 7:50 AM, Ron D'Eau Claire wrote:
>>> Even the Elecraft 100 watt amps are integrated with either the K2 or K3
>>> control logic so they cannot be used as a stand-alone amplifier with other
>>> transmitters.
>>>
>>> The only reason I have ever seen from the FCC for the amplifier
>>> certification and 15 dB gain limitation is to discourage the CB
>>> 'bootleggers'. Certainly building a stable, clean amplifier that would take
>>> even a few milliwatts to 1000+ watts is a straightforward design exercise.
>>> There's no real problem with using more than one stage of gain if there was
>>> no 15 dB limit on the system gain.
>>>
>>> Ron AC7AC
>>
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
> --------------------------------------------------------------------------------
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.872 / Virus Database: 271.1.1/3331 - Release Date: 12/22/10 02:34:00
>

--
Vic
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AC7AC

Re: 100 Watts or 500 Watts

In reply to this post by John Ragle

CONTENTS DELETED

The author has deleted this message.

Tony Estep

Re: 100 Watts or 500 Watts

In reply to this post by John Ragle

On Wed, Dec 22, 2010 at 10:45 AM, John Ragle <[hidden email]> wrote:

> On 12/22/2010 11:30 AM, a lister wrote:
>
> ...When I was little, "grounded grid" was vaunted as the way to use triodes
> without needing neutralization...

Yep. Remember the bifilar filament chokes? You could go to the ham store,
get one of those, a cool litz-wound plate choke, and a bandswitching tank
coil, and the variables you needed for a pi-network output, and build a heck
of an amp.

Another way was the NCL-2000 way, wherein the input circuit was just a 50
ohm resistor and the amp ran in class AB1, using 8122 ceramic tubes. IIRC,
about 50 watts of drive was enough. An amp designed that way could use a
higher value resistor, show the transceiver a mismatch, and get by with less
drive. If you used a 200 ohm resistor and a 4:1 balun, you could probably
drive such an amp to the max with 10-15 watts, no step-up stage required.

Tony KT0NY
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Vic K2VCO

Re: 100 Watts or 500 Watts

In reply to this post by AC7AC

My approach to the harmonic problem is to use a link-coupled antenna tuner on 80-30 meters
(Johnson Matchbox), and a homebrew parallel tuned circuit on 160. On the higher bands, the
simple pi network should be adequate to keep the harmonics down. You could use a pi-L
configuration on the low bands if you wish.

A bigger problem with class-C is how to keep the high bias from sharpening up the
beautiful K3 keying and producing clicks. My approach is to have the QSK circuit drop the
bias below cutoff when the amplifier is keyed, so that the amplifier is initially
operating in the linear part of the curve. There is a resistor in the grid circuit which
supplies the remainder of the class-C bias from rectified grid current. But that bias
rises along with the drive. The bypass capacitor and this resistor form a filter which
keeps the transition to full power clean.

On 12/22/2010 9:20 AM, Ron D'Eau Claire wrote:

> Time to dig out some old ARRL Handbooks from the 60's. My '62 Handbook has a
> nice 813 grid driven amp that runs Class C for CW and AB2 for SSB, the
> famous "one band kilowatt" amplifiers using a pair of 813's (each band had
> its own RF 'deck' with a common power and metering circuit so each amp could
> be pre-tuned and ready to go at the snap of a relay or switch) and a
> Kilowatt grid-driven 4-400A amp, in addition to the usual assortment of
> ground grid amps.
>
> A builder today may need to 'beef up' the pi-network output filter to meet
> modern spurious emission standards (typically for the second harmonic) or
> use an outboard half-wave filter for each band for that purpose.
>
> Ron (radios should glow in the dark) AC7AC
>
> -----Original Message-----
> On 12/22/2010 11:30 AM, a lister wrote:
>
> Grounded-grid is not the only way to design a tube amplifier. Although a
> traditional grid-driven circuit is a little more complicated, it's one way
> to get more gain.
>
> Amen to that. When I was little, "grounded grid" was vaunted as the way to
> use triodes without needing neutralization, even though one took a real hit
> on gain. Unfortunately, the old-time big amps that use/used several triodes
> in parallel in grounded grid still have a tendency to "take off."
>
> The 813 and the various Eimac ceramic tetrodes are wonderful tubes, and if
> one can go high voltage low current, they are excellent performers. Again,
> when I was young, solid state devices wouldn't function in the VHF/UHF
> region, and the 4CXnnn series were practically a necessity. Need I refer to
> the beautiful amps vended by one of the early moonbounce guys?
>
> I for one would like to see designs using these tubes. Not all of us need
> linear/linearized amps.
>
> John Ragle -- W1ZI