[Amps] 600W vs 1.5KW amps was: Re: SS amps and

[BJ]

I used to love heavy legal limit iron and still do.  I like regional ssb rag chewing on 160 & 80.  Like many I have a full size low dipole for this work and can attest that the difference between 600, 1000, and 1500 watts is little if any.  I used to run 1500 watts regularly but sold that capability.  Now I run 600 or 1000 watts because my back can handle moving those amps (Acom 600S & AL-80A) and none of the regulars I communicate with have complained about my non legal limit signal.

If 600 or 1000 watts doesn't cut it, perhaps 1500 may make a difference but having to listen to very noisy band conditions like that for long periods tends to drive me to the recliner and remote control.

I kind of miss seeing the PEP watt meter easily swing to 1500 though!

73, k0cwo

> On Dec 8, 2016, at 8:28 AM, Jim Thomson <jim.thom at telus.net> wrote:
> 
> Date: Thu, 08 Dec 2016 12:48:20 +0800
> From: Alek Petkovic <vk6apk at bigpond.com>
> To: AMPS <amps at contesting.com>
> Subject: Re: [Amps] 600W vs 1.5KW amps was: Re: SS amps and
> autotune...
> 
> I know very little to nothing about the fineries of solid state amps but 
> I do know, that it's the first half kilowatt, whichever way its derived, 
> that does all the work and makes all the difference on the S meter.
> 
> 73, Alek
> VK6APK
> 
> ## The old timers back in the day all said the same thing.  The 1st 500 watts  does all the
> work, the rest just heats up the shack. 
> 
> 100-200  =  3db
> 100-300  =  4.77 
> 100-400  =  6.0 
> 100-500  =   6.99 
> 100-600  =   7.78 
> 100-700  =   8.45
> 100-800  =   9.03
> 100-900  =   9.54
> 100-1000 =  10.0
> 100-1100 =  10.41
> 100-1200 =  10.79
> 100-1300 =  11.14
> 100-1400 =  11.46
> 100-1500 =  11.76 
> 100-2000 =  13.01
> 100-2500 =  13.98
> 100-5000 =  16.99
> 100-10000 = 20.00 
> 
> As you can see, a point of diminishing returns  occurs.  But dbs are accumulative too.
> Going from 600w to 1200w  buys you a lousy 3db. But start doing stuff like using a bigger
> yagi, putting the bigger yagi up higher,  or even putting the existing smaller yagi up higher,
> using lower loss coax, etc, then the additional 3db from the bigger amp..combined with the
> better yagi / coax  setup can easily yield a net 6++ db improvement.... at least on TX.  A .5 db here,
> and 1db there, and a couple more db  from something else...all soon adds up. 
> 
> Tiny incremental increases by themselves may not seem like its worth it, but do a bunch of small
> incremental increases, and it adds up...fast.  Of course the bigger amp doesnt buy you anything on RX,
> but it will if BOTH stations  at each end of the circuit use a bigger amp. 
> 
> You cant work em if you cant hear em.  Well  you cant work em....if they cant hear you. 
> You have to get practical too.  Most folks on postage size city lots are lucky if they can muster up
> an inverted vee at 50 ft on 80m.   2 x similarly equipped stations may well have a hard time talking
> to each other on a noisy summer time 75m band...with each running a 100w Xcvr.  Simple fix is add at
> least a 500w amp...another 7 db..at both stations.   Lower bands with their inherent ant limitations +
> more noise on RX  greatly benefit from more TX  power. 
> 
> For mobile applications, a 500w SS amp  is almost mandatory....esp on the lower bands.   
> 
> Jim  VE7RF
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