[Amps] SS amps and auto-tune. Is it even necessary?

[Roger (K8RI)]

Again, I don't think so.  These new devices don't need much in the way 
of protection, just something to limit the drive and monitor temp.  A 
built in SWR meter would be handy, but not a necessity.

IOW, these are not the equivalent of the early SS amps like the quadra.  
They can take a lot of abuse with fairly simple circuits

It's not just the devices that cost less, the entire circuit costs less 
and is more robust.
When will we see them in commercial ham amps?  They have the potential 
of dropping the amp cost to the point of them becoming a commodity and 
the manufacturers won't want that.

A couple of 2.4 KW PP amps into a combiner could produce a very clean 
legal limit, or even a 3 KW output that is still quite clean. 4800 run 
at 2400 could produce excellent IM numbers.  3KW LP filter kits are 
quite reasonable as are the combiners.  Add the predistortion and the 
signals are outstanding.  OTOH look for some really hefty power supplies.

In the end you could have a 4.8 KW amp for less than the price of many 
legal limit tube amps.
Like tube amps, how they are used will determine the results. How many 
will run the 4800 W capable amp at the legal limit, or hold it at 2400?  
How many will go for the whole 4800?
Like the station on 6 that had a horrible signal stronger than a ham a 
few miles away from me. He wanted power and could care less as to what 
it sounded like.  He just blamed poor receivers.

The new devices lend themselves to more simple circuits.  The LP filters 
can be keyed by the exciter.
External auto tuners are available

73

Roger (K8RI)


On 12/7/2016 12:14 PM, Catherine James wrote:
> On Wed, 12/7/16, Jim Thomson <jim.thom at telus.net> wrote:
>   ##  The low cost of the LDMOS is the least of the issues involved.   Its everything else that’s involved with the SS amp.
>   ##  Jim   VE7RF
>   
> Yep, that's it in two sentences.  That's why I can't get excited about cheap SS finals until I see a complete, commercialized SS amp using them, said amp to be affordable and reliable. Right now they are for experimenters.
>
> 73,
> Cathy
> N5WVR
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