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Author Topic: hf linear kits/ circuit .  (Read 7607 times)
VK4FNRS
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Posts: 16




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« on: December 27, 2012, 07:22:28 PM »

Hi all,

I am in the process of upgrading my lic , from a Foundation , ( Australian ) to a Standard. currently I have a limit of 10Watts PEP.

With the up grade my limit will be 100Watts PEP, and I intend to upgrade from there to an open 400Watts/1000Watts(spec license).

I am looking to build a linear amp for HF 1.8-29Mhz coverage, ham bands only..

Does anyone have recommendations as to a kit/circuit to home brew, as I can not afford to buy a commercial unit, i can spread the cost of a homebrew unit.

many thanks,

Jeff
vk4fnrs
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TANAKASAN
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Posts: 933




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« Reply #1 on: December 28, 2012, 05:55:45 AM »

The only people I know who do kits for 100W linear amplifiers are Communication Concepts:

http://www.communication-concepts.com/

Tanakasan
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WX7G
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Posts: 5917




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« Reply #2 on: December 28, 2012, 07:28:07 AM »

It would be hard to homebrew an amp for less money than an Ameritron AL-811 amp.
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K8AXW
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Posts: 3636




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« Reply #3 on: December 28, 2012, 09:05:25 AM »

Jeff:  I was confronted with the same question and situation many years ago.  I simply didn't have the cash for a new amplifier but could spread the cash outlay over a period of time. 

The "time" part is the hooker.  How much time are you willing to spend building an amplifier?  Do you want to go solid state or tube type?  Have you looked for suitable amplifiers you might be able to build? Have you researched the availability of parts?  What abilities do you have working with your hands and what tools to you have?  Can you troubleshoot electronic gear, especially gear that uses high voltage if you go that way?  Solid state troubleshooting can be even more daunting for some.

At the outset, I would suggest that you research available publications for amplifiers and realistically consider if you can build one that you find suitable.  Don't settle on one but make a list and then narrow the list down to one that satisfies your needs as well as having a parts list that you might be able to deal with.

As you can see the question of rather to build or buy requires a great deal of thought.  In most cases, it's best to simply save your money and then buy one. 

If you have a few minutes, read my story.

http://www.arrl.org/news/build-your-dream

Al - K8AXW
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VK4FNRS
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Posts: 16




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« Reply #4 on: December 28, 2012, 01:30:05 PM »

HI guy's,

thanks for the reply's, 1400Watts will be a bit high for me (not allowed over here), our top limit on a special Lic is 1000Watts.

I am looking at 400Watts max , and I don't plan to have that lic, for at least 12-18 months, at this stage.

My first step is a standard lic for 100Watts, which I can get from my sets now, so the linear will be an on going project.
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M0HCN
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Posts: 473




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« Reply #5 on: December 28, 2012, 02:45:33 PM »

Sounds like a job for EB104 to me (Or one of its more modern variants).

This is not a trivial project by any means, and you will, especially if you have no experience, blow up at least some of the expensive sand before you get the protection circuits right, I may well be tempted to bite the bullet and just buy a KPA500 as a part built 'kit', at least that is known to work well and will have support. 

Note that 400W is only 6db up on 100W, and you can easily make more difference then that with a better aerial system (Which also helps on RX), so make sure that is all it can be first.

73 Dan.
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K9AQ
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Posts: 54




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« Reply #6 on: December 28, 2012, 03:46:06 PM »

Jeff,

I build an EB104 amplifier and spread the costs out over a period of time.  I ended up making numerous modifications that improved the operation and make it a more stable project.  I wrote an article that discusses the mods that I made and also points out an inexpensive source for switched power supplies, and a board for the low pass filters and relays.

If you would like a copy, send me an email at dsolberg@wi.rr.com

I have been using my amp for over a year and it continues to work very well.  I use it every day and am glad that I build it.  Not only does it work well but I was able to learn a lot about solid state amplifiers.

Like the other hams have pointed out, this is not a trival undertaking, but it can be a very rewarding project.

Don
K9AQ
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W9GB
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Posts: 2597




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« Reply #7 on: December 28, 2012, 05:44:33 PM »

The EB104 board from CCI will produce 600 watts PEP
This a set of PARTS, not a Heathkit style kit -- DIY fabrication skills required.
http://www.communication-concepts.com/index.php/amplifiers/eb104.html

IF you desire MULTI-BAND operation with a solid-state amplifier,
then you will need MULTI-BAND switching and Low Pass filtering for the rated power level.
==
HF Projects offers a low pass filter board good for 140 W peak, 100 W continuous duty.
http://www.hfprojectsyahoo.com/kitlplowpafi.html
Virgil will offer a full kit 100-140 W amplifier (SuperPacker Pro), micro-processor controlled in future.
http://www.hfprojectsyahoo.com/hfsupro10amp.html

Your DIY Project could look like G3TSO HF Amplifier, which used the CCI AN762 board,
and a switchable home-brew low-pass filter board for a 100-140 watt class HF amplifier.
http://www.qsl.net/g3tso/HFLinearFrameSet1.html
AN762
http://www.communication-concepts.com/index.php/amplifiers/an762.html
===
Elecraft KPA-500 .... ALL Parts, solid support, assemble the parts for 500 Watt amplifier -- $1,995.00 USD
Assembled is $ 300.00 USD more.
This is the 21st century version of Heathkits -- designed for amateurs with "Build you own PC"  level of skills.
http://www.elecraft.com/KPA500/KPA500.htm
Quote
Does anyone have recommendations as to a kit/circuit to home brew, as I can not afford to buy a commercial unit.
I can spread the cost of a homebrew unit.
The DIY or kit approach is educational/learning, as well as personal pride and gratification in building it yourself.  
IF you don't have that human gene -- then it is a road of frustration.


I find FEW new amateurs (21st century) with Al, K9AXW patience, passion, and perseverance.
In those cases, LEARN financial mgt. (how to save $$), instead of pulling out credit card, taking out a bank loan.
« Last Edit: December 28, 2012, 06:30:27 PM by W9GB » Logged
VK4FNRS
Member

Posts: 16




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« Reply #8 on: December 28, 2012, 08:50:47 PM »

thanks all, this gives me some information to start with.

cheers
jeff
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N4FBW
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Posts: 34




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« Reply #9 on: December 28, 2012, 10:07:02 PM »

Juma offers two very nice 100 watt HF amp kits. You will need SMT soldering skills, though most folks just use a heat gun or hot plate Smiley

http://www.nikkemedia.fi/juma/

The Communications Concepts EB series of amp parts kits look attractive, but building a clean, well performing RF amplifier is not an easy task. However, you will learn a LOT and the end result is really rewarding. Kind of makes that Heath SB-220 amp I helped my friend build back in the 70's look like a cake walk!
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ZENKI
Member

Posts: 906




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« Reply #10 on: December 29, 2012, 01:28:19 AM »

There were some VK4 hams posting here who were building and selling amplifier kits, controllers and low pass filters. The AMPS used the BL177 FETs.
 
www.vk4dd.com

Personally with your limited experience you would be better off just buying a good solid state amp like the Ameritron ALS600 or the Expert SPE1KFA.

Most of the designs that the other have mentioned have design faults and limitation that can easily cost you a lot of money by blowing up FETS.

You can also look on Ebay and buy a ready built amplifier board by Baruch 4z4rb. I number of hams that I know are using his completed modules with good success. They do  look "homebrew" but they  are designed
properly and work well.

Just avoid the CB designs running 2sc2879's and anything that  runs on 12 volts. The last thing you want to be doing is giving yourself away testing a CB amp and causing  a lot of splatter. There are lot of dumb
hams who think that people cant tell that there are running cheap cb splatter box amplifiers like those made by RM  Italy. Get yourself a decent  50 volt FET design kit and you will be on your way.

Get yourself a good SDR receiver like the Perseus or Winradio G31 and use either one of these as a spectrum analyzer  to monitor your output. They fast enough to tell if you have a clean signal even under SSB voice testing conditions.

Stay away from Meanwell power supplies they are a total nightmare to clean up. Even when you add industrial class EMC filters they will wipe out the complete HF spectrum. Either use a non regulated toroidal or conventional transformer. Cleaning up these industrial power supplies will cost you a lot of money in ferrite and filters.

In the meantime while you can only run 10 watts why not just get your antenna up higher. A good beam antenna up at 70  to 100 ft will buy you more than having a poor low antenna down low. I work a lot of your  F calls stations
and everyone seems to be using a G5RV clipped to  the house gutter or  not much higher.   They also seem to have expensive transceivers that buys nothing for their signals. Always spend 9 dollars on the antenna  and 1 dollar on the radio and amplifier. 10 watts into any beam  even a hexbeam at 60 ft and above will produce a very good signal with 10 watts.  Having antenna gain and power amplifier gain  radiated at  the wrong  takeoff angle is useless most of the time.  The takeoff angle gain buys you more than amplifier gain or gain obtained from a longer boom. Put a hexbeam or moxon up on a 70ft to 90ft tower and you will be accused of running a kilowatt by those running there expensive radios and beams that are not higher than the average house roof.   High antennas is what gives you signal might, not an expensive QRO amplifier fed into  poor antenna.

Good luck


Hi all,

I am in the process of upgrading my lic , from a Foundation , ( Australian ) to a Standard. currently I have a limit of 10Watts PEP.

With the up grade my limit will be 100Watts PEP, and I intend to upgrade from there to an open 400Watts/1000Watts(spec license).

I am looking to build a linear amp for HF 1.8-29Mhz coverage, ham bands only..

Does anyone have recommendations as to a kit/circuit to home brew, as I can not afford to buy a commercial unit, i can spread the cost of a homebrew unit.

many thanks,

Jeff
vk4fnrs
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KO4NX
Member

Posts: 179




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« Reply #11 on: December 29, 2012, 06:12:01 AM »

Hello:

Should you decide to build something from CCI, I would recommend you take a look at the AN762 version offered by G6ALU. This version of the AN762 offers some features which CCI does not, such as a switching bias which you will want. The website for this amplifier is (http://www.radio-kits.co.uk/), and while there you should also check out the LPF board he offers, as it is a perfect mate for this amplifier, or the AN762 for that matter.

The boards made by G6ALU are much higher quality, and easier to assemble than the CCI boards I have built. The AN762 by CCI requires a lot of modification before it is ready for amateur use. I have built to AN762's and conducted the modifications to the BIAS circuit required, which was no easy task.  I have mated all of these amplifiers with the G4TZR Low Pass Filter, and IMD (Two-Tone) testing shows that I am meeting or exceeding FCC requirements.  In essence, if you are careful, these amplifiers do not have to be a "Splatter Box", but they can be if you do not use the appropriate filtering and biasing.

In the October 2012 QST there was an article "A Kilowatt on 2 Meters".  While the amplifier in this article was not for HF, some of the Freescale documents suggest one could be built for HF/MF. In either event, this would be a great article to read to get a good feel for the components needed, and what you will be faced with should you decide to construct. Once I am done with my current project, I had planned on building a legal limit SSPA for HF/MF, and was hoping someone had figured a way to do this with the MRFE6VP61K25H by that time!

73

Rich, AJ3G
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W9GB
Member

Posts: 2597




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« Reply #12 on: December 29, 2012, 06:45:19 AM »

Jeff --

In Victoria Australia, Glenn Percy, VK3PE built his own Low Pass Filter for the 140 watt PA section
http://www.carnut.info/star-parts/PANEL-2/LPF/lpf-pcb.htm
of his PICaSTAR DSP transceiver build (he keeps building newer versions for past 5 years).
http://www.carnut.info/star-parts/vk3pebuild/vk3pe_star.htm


« Last Edit: December 29, 2012, 06:55:23 AM by W9GB » Logged
KO4NX
Member

Posts: 179




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« Reply #13 on: December 29, 2012, 06:50:30 AM »

I am almost done with my STAR Build as we speak, which is why I have bult the amplfiers I spoke about in my post. I have used Glenn's boards which are based off of the G6ALU documentation, and they are very good. You cannot go wrong using his boards!

73

Rich, AJ3G
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KE3WD
Member

Posts: 5694




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« Reply #14 on: December 29, 2012, 08:55:03 AM »

Juma offers two very nice 100 watt HF amp kits. You will need SMT soldering skills, though most folks just use a heat gun or hot plate Smiley

One can also use a head magnifier, needle tip regulated iron, tweezers and very thin Eutectic roll solder and do most SMT assembly quite handily.  I have been doing SMT prototype assy and testing of my own designs for more than two decades and that's what I do.  Matter of fact, I've never understood the fear and loathing of SMT that abounds, nor all the hoopla about the "necessity" of solder pastes, adhesives, ovens, hot air soldering, etc.  Those tools are best saved for production run work IMO. 

SMT board population is actually fast when done with iron, tweezers, magnifier and thin sutectic solder.  Faster than thru-hole.  Consider the amount of time spent flipping the board over and over when doing thru-hole, as but one example.  No leads to trim as another. 

Now here will come those who will swear up and down that what I do for a living is impossible and wrong, wrong, wrong...

okay.


73
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