[Elecraft_K3] K3S 630 Meter Quandry


Wes
 

The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:
 

One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.


I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.


However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!


I realize there is the article:

   http://njdtechnologies.net/630-meter-class-de-amplifier/

but this design is non-linear.


I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 

respectable RF output in more of a linear fashion.


Mike,  W0IH

 



Mel Farrer <farrerfolks@...>
 

I h ave designed and build MANY station control console with DDS and buffer linear amplifiers to drive TX.  There is nothing wrong in constructing a station in such a manner and be legal.  What seems to be at issue is a after market amplifier with excessive gain.  This is not the case in getting a home built TX chain up to some reasonable level on 630 meters.  IMHO.  And I might be wrong again....

Mel, K6KBE



From: "Wes wes@... [Elecraft_K3]"
To: Elecraft_K3@...
Sent: Friday, December 29, 2017 2:01 PM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 
The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:
 
One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.

I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.

However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!

I realize there is the article:
but this design is non-linear.

I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 
respectable RF output in more of a linear fashion.

Mike,  W0IH
 




Bob McGraw - K4TAX
 

Of course the FCC allows a ham to  build there own amplifier for their own personal use.  I think there is a limit on the number of units one can produce in a year.  Something like one or two.  So one builds a cascade amplifier, in a single box, that has 30 or 40 dB of gain with a reasonable output power.  After all, in my VHF station I take 1 mw to legal limit power through several stages of amplification.

73

Bob, K4TAX


On 12/29/2017 4:01 PM, Wes wes@... [Elecraft_K3] wrote:
 

The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:
 

One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.


I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.


However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!


I realize there is the article:

   http://njdtechnologies.net/630-meter-class-de-amplifier/

but this design is non-linear.


I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 

respectable RF output in more of a linear fashion.


Mike,  W0IH

 




Mal
 

I think the max power on that band is 5W

 

From: Elecraft_K3@... [mailto:Elecraft_K3@...]
Sent: Friday, December 29, 2017 5:12 PM
To: Elecraft_K3@...
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 

 

I h ave designed and build MANY station control console with DDS and buffer linear amplifiers to drive TX.  There is nothing wrong in constructing a station in such a manner and be legal.  What seems to be at issue is a after market amplifier with excessive gain.  This is not the case in getting a home built TX chain up to some reasonable level on 630 meters.  IMHO.  And I might be wrong again....

 

Mel, K6KBE

 


From: "Wes wes@... [Elecraft_K3]" <Elecraft_K3@...>
To: Elecraft_K3@...
Sent: Friday, December 29, 2017 2:01 PM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 

 

The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:

 

One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.

 

I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.

 

However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!

 

I realize there is the article:

but this design is non-linear.

 

I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 

respectable RF output in more of a linear fashion.

 

Mike,  W0IH

 

 

 


 


Mel Farrer <farrerfolks@...>
 

Yes, 5 W ERP Effective Radiated Power, not transmitter power.  Many of the antennas on 630 Meters are down many dB.  So the input power allowed to the antenna is realitive to the radiation loss.  If the calculated antenna is -10 dB you can run 50 watts into the antenna port.   


Mel, K6KBE



From: "'Mal Speer' malco@... [Elecraft_K3]"
To: Elecraft_K3@...
Sent: Saturday, December 30, 2017 6:49 AM
Subject: RE: [Elecraft_K3] K3S 630 Meter Quandry

 
I think the max power on that band is 5W
 
From: Elecraft_K3@... [mailto:Elecraft_K3@...]
Sent: Friday, December 29, 2017 5:12 PM
To: Elecraft_K3@...
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry
 
 
I h ave designed and build MANY station control console with DDS and buffer linear amplifiers to drive TX.  There is nothing wrong in constructing a station in such a manner and be legal.  What seems to be at issue is a after market amplifier with excessive gain.  This is not the case in getting a home built TX chain up to some reasonable level on 630 meters.  IMHO.  And I might be wrong again....
 
Mel, K6KBE
 

From: "Wes wes@... [Elecraft_K3]" <Elecraft_K3@...>
To: Elecraft_K3@...
Sent: Friday, December 29, 2017 2:01 PM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry
 
 
The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:
 
One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.
 
I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.
 
However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!
 
I realize there is the article:
but this design is non-linear.
 
I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 
respectable RF output in more of a linear fashion.
 
Mike,  W0IH
 
 
 



Rob Sherwood
 

5 watts IERP.  How we are supposed to measure that is a different story.  My Monitor Sensors transverter puts out a nominal 50 watt, though you can push it harder. I don't. 
Rob
NC0B


On Dec 30, 2017, at 7:49 AM, 'Mal Speer' malco@... [Elecraft_K3] <Elecraft_K3@...> wrote:

 

I think the max power on that band is 5W

 

From: Elecraft_K3@... [mailto:Elecraft_K3@...]
Sent: Friday, December 29, 2017 5:12 PM
To: Elecraft_K3@...
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 

 

I h ave designed and build MANY station control console with DDS and buffer linear amplifiers to drive TX.  There is nothing wrong in constructing a station in such a manner and be legal.  What seems to be at issue is a after market amplifier with excessive gain.  This is not the case in getting a home built TX chain up to some reasonable level on 630 meters.  IMHO.  And I might be wrong again....

 

Mel, K6KBE

 


From: "Wes wes@... [Elecraft_K3]" <Elecraft_K3@...>
To: Elecraft_K3@...
Sent: Friday, December 29, 2017 2:01 PM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 

 

The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:

 

One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.

 

I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.

 

However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!

 

I realize there is the article:

but this design is non-linear.

 

I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 

respectable RF output in more of a linear fashion.

 

Mike,  W0IH

 

 

 



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Mel Farrer <farrerfolks@...>
 

Here is a tutorial.

E(I)RP

In most countries there is an E(I)RP limit rather than a TX output power limit. This limit is between 1 and 5 Watt EIRP (except New Zealand with a 25 W EIRP limit).
The effective radiated power (ERP, in W) depends on TX power (P, in W), antenna gain (G, in dBd) and antenna efficiency (η):
ERP = η · P · 10G/10
The ratio between ERP and EIRP (effective isotropic radiated power) is:
ERP = EIRP/1.64   or   ERPdB = EIRPdB - 2.15dB
A small (toploaded) vertical monopole antenna has a theoretical gain of 3 (4.77 dBi or 2.62 dBd). For an unobstructed antenna and a good ground (low loss) the real gain will be close to the theoretical value. But as the ground conductivity drops (and the ground loss rises) the radiation pattern of a vertical monopole will  be affected, resulting in a lower gain.
Obstructions near or even under the antenna will reduce the effective antenna height. The radiation resistance will be less than the theoretical value (based on the physical dimensions of the antenna) and thus the efficiency will drop. Small antennas seem to suffer more from this effect than big antennas. Measurements on 136 kHz have shown that his additional loss can vary from 1 dB (large unobstructed antenna) to 5 dB (small antenna with lot of objects around). On 472 kHz this effect is probably less profound, but with small or heavily obstructed antennas up to 3 dB extra RF power might be needed.
The theoretical gain of a small loop antenna is 1.5 (1.76dBi or -0.39dBd) and is much less affected by obstructions or poor ground.
A result of the rather low E(I)RP limit is that with most antennas (except for very small ones) it is not so hard to reach this limit, it is just a matter of RF power:
  • Case 1: a small toploaded vertical antenna (6 m high and 20 m topload wire) with a radiation resistance RA = 0.1 Ω and a loss resistance RG = 100 Ω.
    The efficiency η = RA/(RA+RG) = 0.1/100.1 = 0.000999 (-30.0 dB) and the antenna gain G = 1.5 (due to very poor ground).
    This means that 667 W RF power is needed to reach 1 W EIRP (1094 W RF for 1 W ERP and 3337 W RF for 5 W EIRP).
  • Case 2: an average toploaded vertical antenna (10 m high with 30 m topload wire) with RA = 0.3 Ω and RG = 50 Ω.
    The efficiency η = RA/(RA+RG) = 0.3/50.3 = 0.00596 (-22.2 dB) and the antenna gain G = 2 (due to poor ground).
    This means that 84 W RF power is needed to reach 1 W EIRP (138 W RF for 1 W ERP and 419 W RF for 5 W EIRP).
  • Case 3: a large toploaded vertical antenna (18 m high with 50 m topload wire) with RA = 1 Ω and RG = 30 Ω.
    The efficiency η = RA/(RA+RG) = 1/31 = 0.0323 (-14.9 dB) and the antenna gain G = 2.5 (due to average ground).
    This means that 12 W RF power is needed to reach 1 W EIRP (20 W RF for 1 W ERP and 62 W RF for 5 W EIRP).
  • Case 4: a "giant" toploaded vertical antenna (50 m high with 100 m topload wire) with RA = 8 Ω and RG = 15 Ω.
    The efficiency η = RA/(RA+RG) = 8/23 = 0.348 (-4.6 dB) and the antenna gain G = 3.
    This means that 0.96 W RF power is needed to reach 1 W EIRP (1.6 W RF for 1 W ERP and 4.8 W RF for 5 W EIRP).
With large antennas it is easy to generate several 10 or even 100 Watts EIRP. Running 500 W RF power into the "giant" antenna (case 4) will result in a theoretical EIRP of 522 W. Even taking into account an additional loss of 2 dB due to a lower effective height the EIRP is still about 320 W!

From 472.ORG.

Mel, K6KBE


From: "Rob Sherwood. rob@... [Elecraft_K3]"
To: "Elecraft_K3@..."
Sent: Saturday, December 30, 2017 10:53 AM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry

 
5 watts IERP.  How we are supposed to measure that is a different story.  My Monitor Sensors transverter puts out a nominal 50 watt, though you can push it harder. I don't. 
Rob
NC0B


On Dec 30, 2017, at 7:49 AM, 'Mal Speer' malco@... [Elecraft_K3] <Elecraft_K3@...> wrote:

 
I think the max power on that band is 5W
 
From: Elecraft_K3@... [mailto:Elecraft_K3@...]
Sent: Friday, December 29, 2017 5:12 PM
To: Elecraft_K3@...
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry
 
 
I h ave designed and build MANY station control console with DDS and buffer linear amplifiers to drive TX..  There is nothing wrong in constructing a station in such a manner and be legal.  What seems to be at issue is a after market amplifier with excessive gain.  This is not the case in getting a home built TX chain up to some reasonable level on 630 meters.  IMHO.  And I might be wrong again....
 
Mel, K6KBE
 

From: "Wes wes@... [Elecraft_K3]" <Elecraft_K3@...>
To: Elecraft_K3@...
Sent: Friday, December 29, 2017 2:01 PM
Subject: Re: [Elecraft_K3] K3S 630 Meter Quandry
 
 
The limit is actually 15 dB.  That said, you can't easily get 44 dB of stable gain from a small signal amp let alone a PA.  So you will have to cascade multiple amps.  I suppose if someone commercially supplies a cascade of amps in one box that might fail the FCC 15 dB requirement, but then 97.315 (b)(3) seems to say a such an amplifier could be sold to a radio amateur for use in his station anyway.  I am not, thank God, a lawyer so I might well be wrong about this.

Wes  N7WS



On 12/29/2017 8:11 AM, mfroster@... [Elecraft_K3] wrote:
 
One of the reasons that I purchased the K3S was because it is capable of working the new 630 meter band.  The power output is something less than 1 mw.
 
I kept thinking that there should be a commercial amplifier available sometime, to take this 1 mw signal and amplify it to a usable output.
 
However, what I'm beginning to realize is that with the FCC limitation of 13 db amplifier gain limit, it will never be available.  It would take at LEAST 44 db of gain to get to 25 watts!
 
I realize there is the article:
but this design is non-linear.
 
I know there are some LDMOS devices that have gains in the order of 26 db (BLF188XR for one) and I'm wondering if there are any similar devices, somewhat lower power, that would take the K3S output to a 
respectable RF output in more of a linear fashion.
 
Mike,  W0IH
 
 
 


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