[Elecraft] 100 Watts or 500 Watts
Frank MacDonell
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
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.
>
able...@aol.com
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 <w3...@embarqmail.com>
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
Don Wilhelm
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
Rick Dettinger
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
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
>
>
>
>
>
ab2tc
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>
>
--
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Dale Parfitt
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
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02:34:00
Don Wilhelm
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.
>
Byron Servies
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 <w3...@embarqmail.com> 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
Igor Kosvin
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
Dave KQ3T
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
>
______________________________________________________________
Ron D'Eau Claire
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
-----Original Message-----
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
______________________________________________________________
Vic K2VCO
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/
Dale Parfitt
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" <v...@rakefet.com>
To: <elec...@mailman.qth.net>
Sent: Wednesday, December 22, 2010 11:14 AM
Subject: Re: [Elecraft] 100 Watts or 500 Watts
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02:34:00
John Ragle
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
Vic Rosenthal
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.
--
Vic
Ron D'Eau Claire
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
Tony Estep
> 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
Vic K2VCO
(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.
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
george fritkin
dissipation, 50 watts of heater power, and a large physical size. The "modern"
572b uses 25 watts for heater power has 225 watts dissipation and is cheap. I
have two SB200s they put out 800 watts PEP and they can be bought real
inexpensive. Every couple of years I stick new tubes in them for kicks and use
the pulls as spares or "presents".
I love building, but I am practical too. But have fun guys and please be
careful.
George, W6GF
________________________________
From: Ron D'Eau Claire <r...@cobi.biz>
To:
Sent: Wed, December 22, 2010 9:20:47 AM
Subject: Re: [Elecraft] 100 Watts or 500 Watts
Time to dig out some old ARRL Handbooks from the 60's. My '62 Handbook has a
WILLIS COOKE
I will throw out another opinion about amplifier gain that has nothing to do
with CB or IMD.
If an operator is currently running QRP at 10, 5 or less watts, adding the KPA-3
to boost power to 100 watts will give you a very large power boost and will be
enough power for a lot of QSOs, both domestic and DX. You can still turn the
K-3 down to 100 mw if you want to give your antennas and patience the acid
test. If you add a 500 watt or bigger amplifier you have another nice boost
in power and you have a combination that will give you smooth power increases
from 100 mw to 500 watts or with a bigger amp the legal limit. To my way of
thinking, this is a better combination than trying to solve the problems of home
brewing or modifing a commercial amp.
Food for thought?
Willis 'Cookie' Cooke
K5EWJ
Ron D'Eau Claire
"nostalgia bottle" for many of us. It was popular after WWII because you
could get them for as little as 50 cents each in the USA. Even in the 60's
they were still available 'surplus' for a few dollars. Typically the socket
cost far more than the tube.
The biggest cost in a tube amp is in the power supply (including high
voltage hardware) and in the input/output network components that can handle
the voltages involved.
You can avoid those costs by buying a used amp, even if it's not functional
(but hopefully has a good power transformer).
Other than learning to work around thousands of volts (only one mistake
allowed per lifetime) tube amps are extremely simple things compared to most
high power solid state amps. And tubes tend to be much more tolerant of
abuse than solid state.
But that comment about only one mistake allowed per lifetime around the
typical tube amp power supply was serious. I'm always very cautious about
encouraging today's typical ham to mess around with even moderate or low
power tube gear if he/she has "grown up" around solid state running from a
few tens of volts at the most. One needs a wholly different set of
procedures, concerns and attitudes to work around even a few hundred volts
safely.
Over the years we've lost a number of wonderful, bright, prolific designers
and builders in the Ham community to one momentary mis-step around a high
voltage power supply.
Ron AC7AC
-----Original Message-----
Just some simple questions. Why use an 813 for an amp. 125 watt plate
dissipation, 50 watts of heater power, and a large physical size. The
"modern"
572b uses 25 watts for heater power has 225 watts dissipation and is cheap.
I
have two SB200s they put out 800 watts PEP and they can be bought real
inexpensive. Every couple of years I stick new tubes in them for kicks and
use
the pulls as spares or "presents".
I love building, but I am practical too. But have fun guys and please be
careful.
George, W6GF
______________________________________________________________
Vic K2VCO
procedures like the use of a 'shorting stick', there are various design principles
important for safety. There should never be a way for someone to come into contact with
HV, no matter what component or combination thereof fails (within reason, of course).
Just for example: you often see a 'safety' RF choke across the output of a pi-network.
Supposedly this will cause a fuse to blow if the plate blocking capacitor breaks down and
puts HV on the antenna. But most such chokes are too puny -- they will blow before the
fuse! Interconnections between remote power supplies and RF decks are another risky area.
I prefer to put it all in one box, or at least an enclosed rack.
I only work on such projects when I am feeling 1) alert and 2) patient. 'Patient' is
really important. If you are operating in the 'every time I try to fix something I break
something else' mode, then STOP. I like to spend a lot of time thinking about what I'm
about to do before doing it.
This is getting off-topic for the reflector, so this will be my last post on the subject!
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
Chuck Smallhouse
'47). I'm still trying to understand all the nuiances of the K3
operation. Thank you, the Elecraft Reflector, for all the good ideas and help.
But as I understand it, the quote of the HF DX'rs is " Life is too
short for QRP", 500 Watts.
So my New Years and B'Day (79) present next month will be a 2nd hand
but good working AL 1500. I really like 8877s. I worked WAS, WAC,
VUCC, and 95 DXCCs on 2M with one, using CW.
So maybe I'll try a bit of HF for a change with my K3/100.
BTW, it should also make and excelent EME transceiver, especially
with the purposed extenal 10MHz driven REF Lock module.
GL es 73,
Chuck, W7CS