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How difficult to build?




 
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n1zpy
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« on: February 09, 2017, 08:00:19 PM »

Hi I am wanting an AM transmitter.  Wondering how hard a class E is to build?  I am a mechanic by trade.  Built my first electronics kit back in hs.  I have soldering equipment multimeters,frequency counters,tools for metal working but no scope or spectrum analyser.  I might be able to take the project to a friend who has the last two items for testing if that is required.  On a scale of 1 to 10 how hard is it to build one of these.  Or should I just try to find an old boat anchor?
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steve_qix
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« Reply #1 on: February 10, 2017, 12:35:39 AM »

From the N1 call - are you in New England?  If so, this project is realistic even for a "first time" build because there are so many experienced class E builders in the N.E. area.

The rigs are not that bad to build at all.  The hardest part is the metal work.  But, it will be advantageous to have class E "Elmers" around to help out, answer questions, and perhaps be there when you get ready to test circuits and fire up for the first time.

I would start out with an 8 MOSFET rig on 75 meters or possibly 75/160 meters.  This design has been reproduced many times, and is quite stable and reliable.

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KD6VXI
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« Reply #2 on: February 10, 2017, 09:27:33 AM »

I did both.

I bought a Viking II.   

I built a PWM and then built various rf decks.

I haven't had the Viking on in almost 2 and a half years.   It's been between my pwm Homebrew and a fairly modified TS 440 Kenwood for me.

I think the stuff I have more of my heart in,  I get more enjoyment out of.

My two cents worth.   Honestly,  I'd be happy with just my viking or my pwm rig.   But,  I haven't sold the viking even tho it's a shelf drag queen.

--Shane
KD6VXI
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VE3ELQ
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« Reply #3 on: February 11, 2017, 08:54:40 AM »

As the old saying goes you climb a mountain one step at a time.
First buy a scope.  You absolutely cannot do this project without one.  The new DSOs are inexpensive and very versatile.
Read up on whats out there and decide on your objectives.  Then start somewhere, probably the power supply, build it test it and when its done build the modulator.  Start by making a dummy load for it, wind some lock wire around a brick to match the deck impedance, then the rest of it, and send some triangle waves into it and see how good it looks on the scope, clip a speaker with coupling cap to it at the bottom turn and play some MP3s and marvel at how great it sounds.  Then do the rest of it one step at a time. Ask questions when you are stuck, someone will have the answer.  You get the idea.  Persist until you reach the summit. Its a great journey.  Have fun.

73s  Nigel
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n1zpy
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« Reply #4 on: February 11, 2017, 01:14:22 PM »

What mhz scope should I be looking for?  Not just to build this but to have for general ham radio use?
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VE3ELQ
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« Reply #5 on: February 11, 2017, 02:59:44 PM »

What mhz scope should I be looking for?  Not just to build this but to have for general ham radio use?

The fastest you can afford but a 70mhz will do a good job for this application.  Many brands are available, Hantek and Rigol make good ones. Go for the extra memory if you can.  Post your choice before you buy and standby for lots of differing opinions on this one.

73s  Nigel
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steve_qix
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« Reply #6 on: February 11, 2017, 08:22:55 PM »

I use a Tektronix 475A, which can be had very reasonably these days.  And it's a really good scope (250mHz).
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High Power, Broadcast Audio and Low Cost?  Check out the class E web site at: http://www.classeradio.org
ka1tdq
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« Reply #7 on: February 12, 2017, 12:29:20 AM »

It looks like you're a fellow Maine-iac.  I'm from the Calais area originally.

I built a single MOSFET transmitter just to get the concept down.  Once I found out how to drive and tune one of these beasts, I felt more comfortable building the 8-FET version. 

I'm now in the process of building a 24-FET model. 

If I hadn't started small, chances are that I wouldn't have been able to build a bigger one.  I'm no engineer, so I had to figure things out step-by-step.

Jon
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #8 on: February 14, 2017, 05:51:46 PM »

Fwiw, used TEK 'scopes are all over the place now. Almost all of them are really excellent.
You can find them used on ebay. At NEARFEST too. Of course you want one that actually works, so
the ebay purchases range from incredible bargains to having one or more functions broken. So,
you have to look carefully. Usually sellers with good scopes will show you pix with the trace
or preferably a signal. ESS in New Hampshire also sells scopes on ebay and their website and
their store too. AL, W1VTP lives a stone's throw away...

A 100mHz scope will likely suffice for most things. Higher freq is better...

I personally do not like the inexpensive digital scopes - can't stand "jaggies" on the trace.

              _-_-
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n1zpy
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« Reply #9 on: February 16, 2017, 06:48:56 PM »

The plans are to make it to nearfest.  Looking for a scope,amp parts,tubes and maybe an old am rig.
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steve_qix
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« Reply #10 on: February 17, 2017, 09:02:18 AM »

There are likely to be some H.B. class E rigs there, too.  You can check them out and see the construction for yourself.
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W3GMS
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« Reply #11 on: February 18, 2017, 11:44:00 AM »

Dale,

With the board kits that Steve offers, you should have little difficulty building a Class E rig.  A lot of the build is mechanical with good electrical layout.  With the digital gate drive its even simpler than before!
Layout is critical in some areas, but once you understand what needs to be where, you should not have any issues.  You have a very large support group out there to answer your questions. 

I am going to tackle the task of building one myself very soon. 

You will learn a lot and have tons of fun in the process, so just do it!

73,
Joe-W3GMS   
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n1zpy
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« Reply #12 on: February 18, 2017, 04:56:22 PM »

There are likely to be some H.B. class E rigs there, too.  You can check them out and see the construction for yourself.
Will you have your boards there?
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