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Author Topic: JUMA PA1000 HF Linear Amplifier  (Read 6002 times)
VE3OCU
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Posts: 4




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« on: March 06, 2014, 09:46:27 AM »

After several years of research & development, it looks like Matti Hohtola OH7SV & Uha Niinikoski OH2NLT HF Linear Amplifier project, the JUMA PA1000 maybe nearing completion...

Through perseverance, they've advanced the state of the art by solving some difficult design engineering challenges.
The total weight for this kit is only 5.5 Kg, and the (unconfirmed) efficiency a staggering (record setting?) 83%!

These guys have a very good track record, and their design ethic implies they're trying to keep the price within reach of meagre Ham budgets... Maybe all things really do come to those who wait?  Smiley

Specifications here: http://www.nikkemedia.fi/juma-pa1000/

de VE3OCU



 
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W9GB
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Posts: 2626




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« Reply #1 on: March 06, 2014, 01:01:32 PM »

The Finnish designed JUMA PA-1000 uses a single Freescale LDMOS MRFE6VP61K25H.
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MRFE6VP61K25H

Freescale is the "spin-off" of the Motorola Division that Finnish-American Helge Granberg (SK, 1996) worked in with Norman Dye and Les Besser during the development of the first solid-state Bi-Polar and MOSFET RF transistors.
https://community.freescale.com/thread/313550
Helge is the Finnish equivalent to Art Collins.

For that reason, JUMA has specific pride in this HF amplifier product / construction project.
The Freescale Labs in Arizona (Donna Vigneri, KF7SJF) has been testing
many potential HF designs for the past few years.
===
A couple of years ago, F5FLN described a 6 meter KW amplifier that he built modeled after the Freescale MRFE6VP61K25H reference design for an commercial FM broadcast (88-108 MHz) amplifier.  The article was published in Dubus magazine (German radio).

Jim, W6PQL has used this Freescale LDMOS for a number of
1 Kilowatt mono-band VHF (6m, 2m, 222 MHz) amplifiers.
Details and assemblies that Jim sells can be found on his web site.
http://www.w6pql.com
« Last Edit: March 06, 2014, 01:22:17 PM by W9GB » Logged
K6JH
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Posts: 42




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« Reply #2 on: March 06, 2014, 06:27:58 PM »

I wonder what kind of Imd they get out of that. I don't find any specs either at the Juma site or at Freescale...
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NO9E
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Posts: 417




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« Reply #3 on: March 06, 2014, 06:55:45 PM »

For IMD please see http://cache.freescale.com/files/rf_if/doc/support_info/RDMRFE6VP61K25H_2MTR_AMATEUR.pdf

Seems IMD3 at 30db point without a feedback is 900W. Feedback or forward correction like in ANAN200S can improve the matter.

Ignacy, NO9E
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KC4MOP
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Posts: 743




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« Reply #4 on: March 07, 2014, 03:44:41 AM »

Would two of the devices working together ease the stress to provide solid operation? Seems like they are pushing the limit.
Fred
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K6AER
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Posts: 3524




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« Reply #5 on: March 08, 2014, 10:10:57 PM »

If the amplifier is marketed in the US the FCC wants the gain limited to 13 dB. Looks very rubust in its construction.

The IMD drops a bit when the amplifier outputs more then 800 watts. The devices have a lot of gain. None the less the amplifier has promising potential.
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F6DEX
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Posts: 9




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« Reply #6 on: March 09, 2014, 11:49:50 AM »

HI

Is this limit also applying for kits ? (Kits do not have any restriction in EU).

I want it for max gain (18-20dB) since I have a Juma TRX2.

Laurent F6DEX
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K6AER
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Posts: 3524




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« Reply #7 on: March 09, 2014, 08:56:47 PM »

Wither the amplifier is manufactured and or sold as a kit, it has to meet FCC regulations. All the amplifier kits I know of the RF deck is pre manufactured.

Basic FCC specifications to meet are the following:

  • Gain must be less than 13 dB.

    The amplifier has to have negative gain from 26-28 MHz.

    Harmonics must be down 43 dB log of the power.

    IMD is not a consideration.

    Harmonics are now measured out to the tenth harmonic.

    Must meet part 15 regulations if there is an oscillator on board. (microprocessor)

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F6DEX
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Posts: 9




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« Reply #8 on: March 10, 2014, 12:20:41 AM »

Juma kits are real kits, not pre manufactured. You get the circuit boards and all the components (generally SMD) with minimal instructions. It is like you buy the schematic and all the necessary stuff separately. Not for beginners (it is not an heathkit or Elecraft).... Certainly, the juma qro amp will be distributed this way ... If it is released.

But just curious. I understand all the fcc rules but not the 13db gain if you build (and even conceive) the amplifier yourself ?.... (not manufactured). Now adding components to satisfy this rule is possible but practically has no sense given the knowledge required to build this kit... (you necessarilly have the knowledge to remove them...).

This of concern for us too... Not because of the rules (there no limit in gain) but because the market is global...

73, Laurent

73, Laurent f6dex
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G3RZP
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Posts: 4715




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« Reply #9 on: March 10, 2014, 12:57:21 AM »

In the EU, kits, homebrew, second hand  commercially made equipment pre-dating the introduction of the Radio & Telecommunications Terminal Equipment Directive and modified equipment are exempt. But  'Unwanted Emissions in the Spurious Domain'(which includes harmonics) are the subject of a CEPT Recommendation (ERC/REC 74-01) which is considered (but not always stated) as a licence condition. Harmonics are measured up to the tenth if that is below 3GHz, the 5th for equipment operating between 600MHz and 5.2GHz, to 26 GHz for equipment operating between 5.2 and 13 GHz and the second harmonic for equipment operating from 13 to 150 GHz. Above that, measurements are not currently made above 300GHz.

Also, a manufacturer with a suitable QA system such as ISO9000 can self certify, which considerably reduces costs.

Using a proper Notified Body doesn't mean that equipment will be compliant once in  production - recent EU scandals on replacement hip joints and breast implants have proved that. Similarly a paging tx that after a power failure, came up on 145.000 MHz was passed by a  UK based Test House.....
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KH2BR
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Posts: 103




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« Reply #10 on: March 15, 2014, 12:36:25 PM »

This is a first class operation, its to bad they are having such a hard time with kitting. A one man kitting company is going to make it very very slow. I have built all of there kits, and I don't think there is any one out there better then them with modern designs and all surface mount construction. There kits are outstanding.
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KD5OEI
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Posts: 10




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« Reply #11 on: March 16, 2014, 06:52:33 PM »

The FCC is overly concerned about the citizens band users on 27MHz. The 13dB gain would limit the amount of power a 'ham radio' amp can make if illegally fed a 12W PEP signal from a CB radio, and the 'hole' at 26-28MHz is to prevent a CB signal from being amplified at all. It's the same issue with forbidding RF-controlled keying.

Because many ham transceivers make 100W PEP, they believe that 13dB is enough for hams.

CBers respond by putting two used amps in series or by having someone build whatever they want. They would put a 100W amp before the 1KW amp to make the gain. The law is old from when CB was popular here, is not considerate of those who want to own only one QRP HF portable, and not effective against the modern radio pirate anyway.
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W0QE
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Posts: 6




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« Reply #12 on: March 17, 2014, 06:12:00 AM »

If you actually look at FCC part 97.317 the gain limit for certifying external amplifiers is 15dB and not 13dB.

Larry, W0QE
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