[Amps] Building amps

[Roger (K8RI)]

On 7/29/2012 5:02 AM, Charles Harpole wrote:

 >From most of the replies, it appears that building some thing has 
 >fallen way down the list of fun ham things to do.  I did like the idea 
 >of a window to watch the 3-500z glow cherry red, the only way to run 
 >them, and the "modern" guys who are now slaves to the "latest and 
 >questionably greatest" SS and so on. Here is something to think 
 >about.............. Ham radio is basically obsolete, with the rare 
 >exceptions of satellites and one or two cutting edge single man 
 >efforts.  Given this, I think we should begin to think of ham radio 
 >the way collectors and users of Model T and other "legacy" cars or 
 >those who fly model airplanes.  These are honorable pursuits and very 
 >fun, but do not depend on fooling themselves that they are "cutting 
 >edge."  In fact, not being cutting edge is part of the fun.  So, I 
 >recommend we return to our roots of being self builders and 
 >experimenters like the good old days. BTW, the day the American govt. 
 >tells me I can not build, in my own home with my own hands,
 >a ham radio amplifier, I am moving out. 73,


I would beg to differ about ham radio being obsolete. No, the technology 
is mostly not leading edge although I understand many of the digital 
modes do come from ham radio.  OTOH there is the motto, "When all else 
fails: Amateur Radio".

There are many things that can cause conventional communications to fail 
both by man and nature. In books I've read on survival training one of 
the first rules is to get your ham license and back up power.

In the case of an EMP or severe solar storm the old "boat anchors" using 
tubes might be the only communications left over a wide area.
As just one example, take hurricane Katrina, People thought their cell 
phones would work. They didn't and the towers that were left standing 
were without power in a matter of hours.

So there is really nothing second to Amateur Radio when it comes to 
emergency communications and particularly over wide areas


>
>>From most of the replies, it appears that building some thing has fallen way down the list of fun ham things to do.  I did like the idea of a window to watch the 3-500z glow cherry red, the only way to run them, and the "modern" guys who are now slaves to the "latest and questionably greatest" SS and so on. Here is something to think about.............. Ham radio is basically obsolete, with the rare exceptions of satellites and one or two cutting edge single man efforts.  Given this, I think we should begin to think of ham radio the way collectors and users of Model T and other "legacy" cars or those who fly model airplanes.  These are honorable pursuits and very fun, but do not depend on fooling themselves that they are "cutting edge."  In fact, not being cutting edge is part of the fun.  So, I recommend we return to our roots of being self builders and experimenters like the good old days. BTW, the day the American govt. tells me I can not build, in my own home with my own hands
,
>   a ham radio amplifier, I am moving out. 73,


I enjoy building to the point where I"ve been assembling a small machine 
shop along with a few instruments to work with and analyze circuits.  At 
one time I had a complete electronics shop, but a couple of decades ago 
decided I was through working on "stuff", but now days I find I have to 
send in a lot of equipment so I'm slowly working on getting it back 
together.

I think it's reached the point where I could build a 2 or 3 KW SS amp 
for about the same price as a tube amp.  Power FETs are getting cheaper 
and tubes are getting a LOT more expensive.  The only drawback I see to 
the SS amp is it needs a lot of protective circuitry, but so do a lot of 
tube amps. They also need a tuner because they need to operate into a 
low SWR.

Some one on here mentioned the 3CX400Us as a replacement for the 
4CX400A7. They were a very good price. In a month or two the price has 
gone up there with the A7s. Whether they'll stay up there or go back to 
their regular price? Who knows.

People call these small ceramic tubes fragile, but if they are handled 
properly  (IE operated within their ratings) They do just fine. No, they 
aren't as rugged as the "big" ceramic or glass tubes, but there are many 
MLA-2500s and Alpha 76 and 78 series amps with original tubes still 
running regularly out there.


73

Roger (K8RI)


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> Charles Harpole
> k4vud at hotmail.com    		 	   		
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