[Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[James F. Boehner MD via Elecraft]

Kevin,

The current FCC rules for certificating a linear amplifier in the US (in
order for a manufacturer to sell them in the US) is described in Part 97:
http://www.arrl.org/part-97-text . Go down to 97.315 and 97.317.  The 15 dB
rule is 97.317 (2).  The history of this rule comes from preventing the use
of amateur radio amplifiers to be used in the class D Citizens Radio
Service.  

Prior to the rule change in 2006, amps could not be sold in the US that
would amplify frequencies between 24-30 MHz.  The individual ham would have
to do the modification themselves (or have someone do it for them), and
could only receive this modification information if they could prove that
they had a valid FCC Amateur Radio license. For example, my Alpha had a
numerical code sequence tied to the serial number that was given to me after
proof of licensure, one of my MFJ mobile amps had a modification kit, and
another required wiring changes.  So, two conditions had to be met - no
amplification above 24 MHz, and the amp could not have a gain of more than
15 dB.  Again, this prevented, or attempted to prevent, those in the Class D
Citizens radio service from amplifying their 5 watt transceivers to the full
amateur radio legal limit.

Blocking 24-30 MHz from amplification was a bit of a hardship and an
unnecessary rule for the amateur radio service. To simplify,  the FCC
instituted a rule change in 2006, ruling that amateur radio amplifiers just
must have zero gain from 26-28 MHz.  However, the FCC did not remove the 15
dB rule at the time of that rule change, which most agree is also totally
unnecessary.

Expert Linears and the ARRL have both petitioned the FCC to remove the 15 dB
rule.  These petitions are still currently pending FCC review and action.

Should the FCC delete the 15 dB rule, amplifier manufacturers will be able
to build amps that will only require QRP power to obtain full legal limit
power, and be able to obtain FCC type certification to sell them in the US.
The question posed was whether Elecraft will offer a modification program, a
kit or modification instructions should the 15 dB rule be deleted.  The
answer, of course, was TBD.

For Elecraft, this means a KX3 or a KX2 could be amplified to full legal
limit.

So, this is the history as I know it.  I'm sure if I have anything wrong,
There will be more reply posts on this subject than Wayne received after his
KPA1500 announcement last evening!

'73 de JIM N2ZZ

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Kevin
Cozens
Sent: Friday, April 21, 2017 5:52 PM
To: K2
Subject: Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

On 2017-04-21 06:43 AM, Richard Thorne wrote:
> So if and when the FCC lifts the 15db gain rule

For those of us not in the US and subject to FCC rules, what is the FCC 15dB
rule?

--
Cheers!

Kevin.

http://www.ve3syb.ca/   |"Nerds make the shiny things that distract
Owner of Elecraft K2 #2172  | the mouth-breathers, and that's why we're
 | powerful!"
#include  | --Chris Hardwick
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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Ken K6MR]

“any non-USA ham can bypass the input to enable lower drive
requirements.”

Legal for US hams also. Restriction is just on the manufacturer. You are 
responsible for your equipment.
My KPA500s are modified for lower drive (thanks to NX1P who did the hard work) 
so that I can drive two in parallel.

Ken K6MR

From: Edward R Cole<mailto:kl...@acsalaska.net>
Sent: Friday, April 21, 2017 5:03 PM
To: Elecraft Reflector<mailto:elecraft@mailman.qth.net>
Subject: Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

A little more background for the FCC (USA) gain restriction for HF amplifiers:

I believe that was a result of wanting to stymie CB use of ham
amplifiers using 5-15w drive.  15-dB for 1500w implies 47w min drive.

The LDMOS being used for 1200w on 2m only require 3-4w drive; that is
26-dB gain!  Likely the devices chosen by Elecraft for their KPA1500
have similar gain so they install attenuation into the drive path or
change bias to lower gain (or both).  My guess once the schematic is
available any non-USA ham can bypass the input to enable lower drive
requirements.  A KX2 or KX3 ought to suffice.

Of course this would violate warrantee.

On a similar thought process, now that the KX3 is capable of 15w, I'm
wondering if driving the KXPA100 harder than 8w will result in higher
output?  Would it be safe to do?
I'm thinking 10w/100w.  The KXPA100 I have drives easily to 110w
saturated with about 4-5w on 80-15m, but requires 8w to achieve 70-80w at 6m.

73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
   dubus...@gmail.com

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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Edward R Cole]

A little more background for the FCC (USA) gain restriction for HF amplifiers:

I believe that was a result of wanting to stymie CB use of ham 
amplifiers using 5-15w drive.  15-dB for 1500w implies 47w min drive.


The LDMOS being used for 1200w on 2m only require 3-4w drive; that is 
26-dB gain!  Likely the devices chosen by Elecraft for their KPA1500 
have similar gain so they install attenuation into the drive path or 
change bias to lower gain (or both).  My guess once the schematic is 
available any non-USA ham can bypass the input to enable lower drive 
requirements.  A KX2 or KX3 ought to suffice.


Of course this would violate warrantee.

On a similar thought process, now that the KX3 is capable of 15w, I'm 
wondering if driving the KXPA100 harder than 8w will result in higher 
output?  Would it be safe to do?
I'm thinking 10w/100w.  The KXPA100 I have drives easily to 110w 
saturated with about 4-5w on 80-15m, but requires 8w to achieve 70-80w at 6m.


73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubus...@gmail.com 


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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Kevin Stover, AC0H]

This is correct.


On 4/21/2017 5:00 PM, Rick WA6NHC wrote:
It is a rule that an amplifier in the HF bands cannot have more than 
15 db gain.  This is because stupid people do stupid things here (and 
I'm sure elsewhere too).  So it was simpler to block everyone, then 
stop some.


Rick nhc


On 4/21/2017 2:51 PM, Kevin Cozens wrote:

On 2017-04-21 06:43 AM, Richard Thorne wrote:

So if and when the FCC lifts the 15db gain rule


For those of us not in the US and subject to FCC rules, what is the 
FCC 15dB rule?




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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Rick WA6NHC]

It is a rule that an amplifier in the HF bands cannot have more than 15 
db gain.  This is because stupid people do stupid things here (and I'm 
sure elsewhere too).  So it was simpler to block everyone, then stop some.


Rick nhc


On 4/21/2017 2:51 PM, Kevin Cozens wrote:

On 2017-04-21 06:43 AM, Richard Thorne wrote:

So if and when the FCC lifts the 15db gain rule


For those of us not in the US and subject to FCC rules, what is the 
FCC 15dB rule?




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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Kevin Cozens]

On 2017-04-21 06:43 AM, Richard Thorne wrote:

So if and when the FCC lifts the 15db gain rule


For those of us not in the US and subject to FCC rules, what is the FCC 15dB 
rule?


--
Cheers!

Kevin.

http://www.ve3syb.ca/   |"Nerds make the shiny things that distract
Owner of Elecraft K2 #2172  | the mouth-breathers, and that's why we're
| powerful!"
#include  | --Chris Hardwick
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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Oliver Dröse]

PLEASE do it!

Don't "punish" everybody outside the U.S. where this stupid limit never 
existed!


Thanks,
Olli - DH8BQA



Am 21.04.17 um 18:01 schrieb Wayne Burdick:

TBD.

Wayne
N6KR



On Apr 21, 2017, at 3:43 AM, Richard Thorne  wrote:

So if and when the FCC lifts the 15db gain rule, will there be a mod available 
to increase the gain capability so a KX3 or KX2 could drive this bad boy?

Rich - N5ZC
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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[David Woolley]

As I understand the way things work, they will not get approval for the 
device, if it is easily modifiable to defeat the current limit, so I 
would expect them to play down any modifiability even if it can't be 
classed as easy.


--
David Woolley K2 06123

On 21/04/17 11:43, Richard Thorne wrote:

So if and when the FCC lifts the 15db gain rule, will there be a mod
available to increase the gain capability so a KX3 or KX2 could drive
this bad boy?



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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Clay Autery]

Excellent question.

Do not expect an authoritative answer until AFTER the ink is dry on the
gain limited approval from the FCC.  ;-)

__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 4/21/2017 5:43 AM, Richard Thorne wrote:
> So if and when the FCC lifts the 15db gain rule, will there be a mod
> available to increase the gain capability so a KX3 or KX2 could drive
> this bad boy?
>
> Rich - N5ZC

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Re: [Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Wayne Burdick]

TBD.

Wayne
N6KR


> On Apr 21, 2017, at 3:43 AM, Richard Thorne  wrote:
> 
> So if and when the FCC lifts the 15db gain rule, will there be a mod 
> available to increase the gain capability so a KX3 or KX2 could drive this 
> bad boy?
> 
> Rich - N5ZC
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[Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Richard Thorne]

So if and when the FCC lifts the 15db gain rule, will there be a mod 
available to increase the gain capability so a KX3 or KX2 could drive 
this bad boy?


Rich - N5ZC
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