[AMPS] Henry 4K Ultra vs. 3K Classic X Mk II

[Steve Katz]

> >
> >Mike, unless Henry has come back out with the 4K Ultra, that's a rather
> old
> >design that's "continuous tune" from 3.5 through 30 MHz and offers
> excellent
> >coverage of frequencies between the ham bands, so used to be popular with
> >government agencies, embassies, etc.  It had some neat features like a
> >filament voltage adjustment and test points, 
> 
> //  Excellent idea.  Some Collins amplifiers had this feature.  
> 
> >not normally found on amateur
> >equipment.  It's a good amp, but does not cover 160m and requires the
> >typical "8877 three minute warm-up," which can be frustrating (for me).
> >
> //   Amen
> 
> >I just sold a 3K Premier (which is a 3K Classic X Mk III, virtually no
> >difference with the Mk II) which had 160m coverage.  I don't recall if
> the
> >"Mark II" covers 160 or not, maybe not.  The Mk III definitely does, as
> does
> >the "Premier," whatever that means.  This was obviously a rather huge
> cost
> >adder, as Henry used large B&W coil stock (not a toroid) to add 160m, as
> >well as lots of HV doorknob padders switched in by their famous plunger
> >switches driven by the bandswitch which also drives a chain, pulleys,
> >triple-action camshaft (only kidding) and all that stuff that makes the
> >bandswitch difficult to turn.
> >
> >I might have had a parasite problem with the 3K Premier, never
> investigated
> >fully enough to ascertain; however I used to use the amp quite a lot on
> the
> >lower bands (160, 80, 40) and one day noted a large change in the way it
> >tuned on 40.  Still made 1500W output, but tuned in a different point,
> >leading me to believe something failed.  Sure enough, investigation
> revealed
> >two doorknob caps had cracked in half, leaving pieces of ceramic material
> >laying around inside the RF cage, and with that, their values had
> obviously
> >changed (or possibly dropped to zero).  These were 7500V caps 
> 
> //   What were the C values?
> 
> ::I don't recall, but in the 100-300pF range, I believe (plate tuning pi
> input padders)
> 
> >-- Henry
> >doesn't really skrimp on components.  
> 
> //  Henry Radio resonant-choke power supplies are formidable.  
> 
> >The parasitic suppressor on the
> >3CX1200D7 still looked fine, although I didn't isolate the resistor from
> the
> >inductor to measure the R.  But something made those doorknobs blow.
> >
> //  My guess is that it probably wasn't a parasite.
> ::Maybe not, I never found out.  The funny thing about the pi-L circuits
> used by Henry in most of their amps is that they will resonate with many
> combinations of C and L, and since everything is fully adjustable
> (including the L), one can achieve 1500W output with lots of tuning
> combinations.  There is only one "most correct" combination, that results
> in max output with minimum input power (and also minimum grid current),
> and it can take some time to find that point.  Then, changing antennas
> creates the need to go through the hunt once again...
> 
> > ...
> 
> cheerz
> >
> >
> >> Henry 4K Ultra (3CX1500A7) vs. 
> >> Henry 3K Classic X MkII (3CX1200A7) 
> >> > I have the opportunity to purchase one of these two amps.  Any help
> with
> >> > the pros/cons of each would be appreciated.  Thanks.  Mike-K6QD
> >> 
> >> 
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> >
> >--
> >FAQ on WWW:               http://www.contesting.com/FAQ/amps
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> >
> >
> 
> 
> -  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
> end

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