[AMPS] How to build the ultimate HF amplifier ?

[Jim Reid]

>At 12:04 30/10/98 PST, 

somebody (hi!) wrote:

>>I think the really ultimate home brew amp would have 
>>different PI-tanks for each  band arranged around 
>>the tube. (If size isn't a BIG matter)


Seems to me that Henry Amplifiers,  at least in the Ultra
unit I now have on order,  solved  this feature:  that is,  preset
tuning on many bands.  In a nice desk top and
compact way;  within the desk top Controller box,  that is,  with
the  amp/PS/heat  and audible blower tucked away elsewhere OUT
of the shack!

Have a look at:
   
    http://radiodan.com/Henry/Amp_specs/ultra_info.htm

buttons across the Controller unit front are presets.  

What Henry engineers and techs have done is the following:

Pairs of small,  precision pots  are arrayed either under 
the Controller top lid,  or on 4" wide matching boxes beside the desk
top Controller unit, up to 24 preset tuning set-ups.  A push of 
a button,  and bingo,  within about 20 to 30 seconds,  the
amp can QSY from 160 to 10,  and be tuned and ready
to go on a preset range of frequencies.  Within a band,
just a few seconds.  As with any amp,
the range where the tuning/match will be good depends
upon the antenna system impedance over the frequency
range to which one QSY's.

With up to 24 presets offered,  you can preset a few on each
of the bands on which you are most likely to be operating,
and if you move about,  say from CW to SSB from 80 to 75,
you might want up to four preset just for that range.
Out here I will likely only need two on 40,  for example,
one centered around 7015 or thereabouts,  the other
about 7085 or so,  will depend upon what the vswr
limits that the Henry will load into across each band's
range where I am usually camping.  Because of the
powerful BC stations West of Kauai,  40 above 7100
is not too useful out here.

Seems to me this is  somewhat more elegant than adding
several PI elements around the tube.  But yes,  building yourself
may be less costly than buying a new Henry Ultra,  hi.  And sure,
the presets of a   microprocessor controlled Alpha 87A are faster
and more elegant,  I suppose.  Clearly Topband to 10 meter
QSY is very quick with the Alpha,  but how often might you
do that??

Don;t know if Henry's Ultra amps are the ultimate in an amateur
band amp;  they sure are HEAVY,  but they do offer many/all
of the features and operating advantages which will benefit
my DX operating.  Can hardly wait for it to come,  but will
be a couple of months (be that long before I can pay for
the rest after the down payment,  hi!)

73,  Jim, KH7M
    


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