Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: 6 meter amp  (Read 556 times)
KA3NXN
Member

Posts: 109


WWW

Ignore
« on: October 03, 2007, 08:43:14 AM »

Hey Gang,

I am looking for plans or any kits that are available for a 6 meter amp. I am looking for 500-1KW for 6M SSB mainly. Solid state or tube is fine. I checked communication concepts ant their 600 watt amp will only go to 50MHz. I'm sure I could possibly modify it to cover up to 53MHz or it may just do that on it's own, but I didn't want to mess with it too much.

Thanks

Jaime-KA3NXN
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #1 on: October 03, 2007, 08:57:30 AM »

Unless you want to use it mobile, I'd avoid solid state for this.

The power CCI kits as you might know (I've built six of them over the years) are "semi kits," nothing like a Heathkit.   They provide the circuit board and a bag of parts, a Motorola application note and a thank you note.  They do not provide heatsinks, chassis, relays, RF connectors, fuse holders, fans and many other things you'll need to make a complete amplifier.  Of course, that's part of the fun of it: It's like a real homebrew project, where someone just happened to go shopping in advance for a lot of the parts but you still have to do design work, chassis work, machining and so forth on your own.  

The problem is, the resulting amplifier is a pain.  You need a huge power supply (if you don't already have one): The 600W PEP model draws about 90A peak.   An Astron 70A supply doesn't come close.  If you don't already have the supply, buying one could cost $500...and building one just a bit less than that.

And even then, the resulting amp's IMD performance is not great.  If you live in the boonies with no neighbors, this may not matter much.  Here where I live, my local six meter friends would jump down my throat if I had a wide signal.

As such, and having been a six meter enthusiast for about 38 years or so, I'd recommend "tubes."  Cleaner, easier, more power and generally more bang for the buck.

If you're handy with tools, an "easy to build" kW amplifier is well described with schematics, pictorials, photographs, parts list and everything beginning on Page 30 of CQ Magazine, July 1987 issue.

That's an article I wrote about an amplifier I built, and it's been duplicated many times.

WB2WIK/6

Logged
KE3WD
Member

Posts: 5689




Ignore
« Reply #2 on: October 03, 2007, 09:02:56 AM »

Surplus Telco "rectifier" PSUs can make dandy cost-effective power supplies for that Motorola FET power amp board.  Dirt cheap.  

But if you are stationary and want 6 meter clout, there is nothing like a tube.  

One wonders where all those gummint surplus 6 meter dual 3-500Z amps went, likely to 11 meters, unfortunately.  But keep your eyes open for those, even if altered for 11, could be put back in shape if not overly abused already.  

For a singleband amp, the expense and bother of solid state, which is broadbanded, may not be the best choice, depending upon application.  If mobile, then you would probably want to go solid state, of course.  But not absolutely mandatory either.  


KE3WD
Logged
N3OX
Member

Posts: 8847


WWW

Ignore
« Reply #3 on: October 03, 2007, 09:10:40 AM »

"For a singleband amp, the expense and bother of solid state, which is broadbanded, may not be the best choice,"

Especially at 6m where you have to buy relatively expensive RF fets.

Down on 160m and 80m it seems people are getting pretty good gain out of dirt-cheap ($5-$10) power Mosfets designed for inverter switching applications.

You still need a pretty big power supply but you can often up the supply to 50V+ with fairly high voltage fets.

I don't think any of that applies to 6m with currently available devices.  Seems like the solid state 1kW FET amplifiers that cover HF and 6m are using $150+ devices, aren't they?

Dan

Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3OX
Member

Posts: 8847


WWW

Ignore
« Reply #4 on: October 03, 2007, 09:20:19 AM »

By the way, can anyone recommend a good book on serious solid state amplifier design?

Namely, one that covers linearity and IMD issues very well...

I am actually looking at building a power Mosfet low band amp, and I already have many parts (including the expensive bits of a big DC supply) and a design I might try, but I'd like to know what I'm doing instead of just copying a design.

Dan

Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
WB2WIK
Member

Posts: 20611




Ignore
« Reply #5 on: October 03, 2007, 09:24:55 AM »

I looked it up, this is a different amp than the last one I built which used bipolars.

The new amp uses a pair of MRF-154s which cost $892 a pair.  But they are 50v devices, so the power supply only needs to deliver 50v at 40-50A.

So, that actually is better than bipolars running at 13.8V, and it is true a Telco -48V/50A power supply should work fine and they are pretty easy to find.

But the total cost of this kit is well over $1K, and for that cost I could nearly build an 8877 amp (using a tube "pull") that runs 1500W PEP with 60W drive (or 1 KW PEP with 40W drive) and have an amp that I could trust to work for 25-30 years before I'd have to worry about finding another tube.

WB2WIK/6
Logged
N3OX
Member

Posts: 8847


WWW

Ignore
« Reply #6 on: October 03, 2007, 09:26:15 AM »

"which cost $892 a pair"

Good god... better be sure your SWR protection is super fast...

Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
WA1RNE
Member

Posts: 825




Ignore
« Reply #7 on: October 03, 2007, 09:51:07 AM »


  A cheaper alternative might be a converted Heathkit SB-200/201 or SB-220.

 Not sure what you have available for drive, but if its a modern HF-6 transceiver, you're all set.

 
 KM1H seems to have this down pat and the price is very reasonable considering the alternatives. An SB-200 complete is $695 including shipping, $395 if you provide the unconverted amp.

 http://www.uksmg.org/1kw.htm

 
 Or you could try your hand at converting one yourself, but if you haven't done the research, $695 is a pretty good deal for a ready to play 650-750 watt desktop amp for 6 meters.

 
 ...WA1RNE
Logged
WA6HDZ
Member

Posts: 52




Ignore
« Reply #8 on: October 03, 2007, 03:49:34 PM »

Dan- most of the books I've seen are composites of old app notes- you can save money and go to the source.  Good design notes are available from Polyfet, MaCom, Freescale (formerly Motorola) and others.  Acrian did some good stuff in VHF linear amps back in the day but I don't know if their notes survived to the web era.

Big problem with cheaper (usually 12V)VHF transistors is that most were designed for FM and other non-linear work.  There are better parts out there for linear amps but most are designed to run at higher voltages. Much lower production volume, too, which explains the $$.

Ken
Logged
WA3SKN
Member

Posts: 5496




Ignore
« Reply #9 on: October 04, 2007, 06:56:25 AM »

Not sure why you need that much power on 6 meters, but Tokyo Hy-Power's amplifier line-up covers 6 meters.
They are not a kit, though.

-Mike.
Logged
N3OX
Member

Posts: 8847


WWW

Ignore
« Reply #10 on: October 04, 2007, 07:19:44 AM »

"Not sure why you need that much power on 6 meters,"

To work stations that can't hear you at 100W?

Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KE3WD
Member

Posts: 5689




Ignore
« Reply #11 on: October 04, 2007, 04:55:04 PM »

Good yagi would do the trick...
Logged
W1QJ
Member

Posts: 1458




Ignore
« Reply #12 on: October 09, 2007, 04:26:47 AM »

Available for immediate delivery: Hethkit SB-200 converted solely for 6 meters. New tubes installed, soft keyed,variable tuned input,(this feature NOT offered by others) all parts installed specifically for 6 meters.  Loafs at 600 watts out and will do as high as 800 out with 100 watts drive.  Professional conversion by King Converisons.  Original offering....$750.00  73 Lou
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!