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Do these images make you go all misty eyed? You are not alone (apparently).
Pull yourself together and visit V.M.A.R.S.

Having listened for some time to the (mostly) nice sounds coming from the AM nets I decided to join in. Most modern solid state equipment will give a very passable performance on AM if its set up right, but many argue its not like the real thing. Fair comment I thought, so having initially joined the fray using an Icom transceiver, in 2005 I took the plunge and eBayed myself a Codar AT5. One of the best, or worst things I ever did. You decide ...

Note the front panel switch top right is a non-standard modification. I think someone before me modified it for MW use and it needed a bit of work to put it back on 160/80.

The mains psu was minus case, and in poor condition, so I decided to rebuild it in a new case using silicon rectifiers. Most of the other components are original.

The AT5 has been great to play with. Just for the hell of it I even replaced the VFO with a PIC controlled DDS signal source at one point, probably a unique act of lunacy never to be repeated. But there's only so much fun you can get out of half a dozen valves, and during 2006 I decided to experiment with a solid state replacement, having discovered the joys of low cost FETs and series modulation. This was operated into my Acom 1000 linear to give an effortless 100W + carrier and proved very effective (photos below).

In early 2007 (obviously short of something to do and not getting out much) I decided to build a 100W all solid state 80m AM transmitter using a Class E high efficiency PA design. Based on Class E work done in The States, notably by Steve Cloutier, WA1QIX. (see www.classeradio.com) I developed a version for UK power levels using series modulation (see photo below). As far as I know this was the only 100w home brew Class E solid state AM transmitter in use in the UK in 2009. It's now 2010 and the number of FAT5 projects completed or on the go is increasing all the time. Long live home brew!

For more photos of the various innards and a few mishaps along the way, click here . On the site, press "slideshow" or select pictures individually.

This is my 100W 80m Class E transmitter. Forerunner to the FAT5 . The same pair of FETs are in use almost three years later (three quid each off eBay)

Class E? "Sorry, I don't do 'modern' ..."

Actually the technique is older than you may think. Class E was proposed in an IEEE paper way back in 1977. Recently low cost high current switching FETs as used in SMPSUs and industrial control have made Class E a viable option.

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AM PAGE I think, therefore I "AM " [apologies to Descartes]
	[Home]
	Do these images make you go all misty eyed? You are not alone (apparently). Pull yourself together and visit V.M.A.R.S.
	Having listened for some time to the (mostly) nice sounds coming from the AM nets I decided to join in. Most modern solid state equipment will give a very passable performance on AM if its set up right, but many argue its not like the real thing. Fair comment I thought, so having initially joined the fray using an Icom transceiver, in 2005 I took the plunge and eBayed myself a Codar AT5. One of the best, or worst things I ever did. You decide ...


	Note the front panel switch top right is a non-standard modification. I think someone before me modified it for MW use and it needed a bit of work to put it back on 160/80.	The mains psu was minus case, and in poor condition, so I decided to rebuild it in a new case using silicon rectifiers. Most of the other components are original.
	The AT5 has been great to play with. Just for the hell of it I even replaced the VFO with a PIC controlled DDS signal source at one point, probably a unique act of lunacy never to be repeated. But there's only so much fun you can get out of half a dozen valves, and during 2006 I decided to experiment with a solid state replacement, having discovered the joys of low cost FETs and series modulation. This was operated into my Acom 1000 linear to give an effortless 100W + carrier and proved very effective (photos below).

	In early 2007 (obviously short of something to do and not getting out much) I decided to build a 100W all solid state 80m AM transmitter using a Class E high efficiency PA design. Based on Class E work done in The States, notably by Steve Cloutier, WA1QIX. (see www.classeradio.com) I developed a version for UK power levels using series modulation (see photo below). As far as I know this was the only 100w home brew Class E solid state AM transmitter in use in the UK in 2009. It's now 2010 and the number of FAT5 projects completed or on the go is increasing all the time. Long live home brew! For more photos of the various innards and a few mishaps along the way, click here . On the site, press "slideshow" or select pictures individually. *This is my 100W 80m Class E transmitter. Forerunner to the FAT5 . The same pair of FETs are in use almost three years later (three quid each off eBay)* Class E? "Sorry, I don't do 'modern' ..." Actually the technique is older than you may think. Class E was proposed in an IEEE paper way back in 1977. Recently low cost high current switching FETs as used in SMPSUs and industrial control have made Class E a viable option. [Home] r ...

AM PAGE I think, therefore I "AM " [apologies to Descartes]

AM PAGE

I think, therefore I "AM " [apologies to Descartes]