Bill,
I agree with you on the balance. Got graded down in college for setting the
current through a voltage divider net too high. My logic, it would be less
susceptible to noise and other influences. My profs argument - build to
spec, and don't assume that you have more of any asset (in this case Icc)
handy that what you do. Good lesson.
But what I thought of just now is that there is really not a universal
standard on what is "good amp design" and what is not. The reason for that
is there are economics and other factors which may exist for one guy, and
not for another. That's really the reason we see such a spread of products
on the commercial side (where minimalism is needed to get an enterprise
profitable), and on the home brew side where a guy may decide to "cook one
the way I like it done."
Case in point. Alpha amps. Famous brick on key demo at Dayton - turns out
the key was wired to a keyer and the amp was running 50% duty cycle via the
K3. Is that coincidence or a reflection that, brick on key really means
ICAS in the Orr sense of the word (5 min on, 5 min off). To me, brick on
key means CCS for the entire box.
73/jeff/ac0c
--------------------------------------------------
From: "Jim Thomson" <Jim.thom@telus.net>
Sent: Tuesday, March 23, 2010 8:55 PM
To: <amps@contesting.com>
Subject: [Amps] Good engineering
> ORIGINAL MESSAGE:
>
> On Mon, 22 Mar 2010 19:31:09 -0700, "Jim Thomson" <Jim.thom at telus.net>
> wrote:
>
>>
>>## I wouldn't be holding Command or anybody else up as any kind of
>>'standard of engineering excellence.' If these ham amps were built
>>right,
>>they would all have individual, adjustable bias for each tube, plus
>>mating
>>metering, real bandswitch's and real tank coils, and plate xfmrs... and
>>maybe
>>toss in a real tube..... and not something with a floozy 4 watt delicate
>>grid.
>
> REPLY:
>
> Any fool can overbuild a product. Good engineers know when to stop,
> and good engineers get paid good money to get it right.
>
> 73, Bill W6WRT
> ## Bill , got any idea what 3 x NEW EIMAC 3CPX-800A7's cost these
> days? ##That's the tube line up used in the HF-2500E.. really smart. The
> 12 ga wireroller inductor,used in the 10 kw palstar ant tuner is a joke,
> along with SO-239's,and the mickey mouse balun on the INPUT of the tuner..
> which will explode. Toss in undersized tank coils, bandswitch's, mickey
> mouse tune/load padding schemes,t/r relays that hot switch, and you
> wonder why the HB amp builder gets into designingand building his own
> stuff. Ten tec brags abt the 3.5 kva CCS xfmr used in the centurion,and
> sez it's good for 7 kw.."IVS" [int voice service], yet it barely does 1.3
> kw pep out....[almost legal limit]. A buddy accidently had his cat fall
> asleep on his footswitch for 2 hrs.His 87-A was pumping out a 1.5 kw FM
> cxr on 29.650 mhz. He had the optional cooling fan.The RF deck had
> turned into molten glop ! Alpha tech tells him..... " don't believe the
> hype"The home builder has the luxury of using what
> ever components he wants.. and can get hishands on. Typ ham amps have
> cut every corner there is. 1/4"-3/8"-1/2" cu tubing is cheapat home
> depot... so why melt airdux ? Ceramic vac caps are readily available, so
> I use em fortune and load. If something is marginal... I re-design it.
> Who's the fool ? later... Jim VE7RF
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