From: Jim Thomson
Sent: Wednesday, March 24, 2010 6:57 AM
To: amps@contesting.com
Subject: Good engineering
Date: Wed, 24 Mar 2010 04:12:21 -0400
From: Roger <sub1@rogerhalstead.com>
Subject: Re: [Amps] Good engineering
OTOH as you say, building a truly bulletproof amp would put it out of
the reach of all but a few hams making it an uneconomically viable
commodity.Those who really want the
best, "to them" either build, or have an amp custom built. Yes, you can
get the 3 and 4 CX 3000 and 5000 pulls are reasonable prices, but you
don't find pulls in new amps. OTOH a yc-156 pull at $385, or a yc179
pull at $575 is really a bargain for a custom built or home brew amp and
you really don't have to move to the farm so you can install a 3-phase
power supply.
Although a good, well regulated, low ripple 3-phase supply
is easier to build than a single phase.
## Which requires a triple core plate xfmr, 6 x leg bridge, 3PST contactor to
apply the juice...and 3 x step start R's... one per pri winding. Also
requires
another 3PST contactor to shunt the 3x step start R's. A 3 Pole breaker
is required. I dunno what happens if you lose one of the 3 x phases.
I'd really like to have amps on
HF and 6 meters like that, but I'm afraid some one would notice.
## No one would notice. Everybody else already has one.
I'm
probably (strike that probably) more afraid of my wife noticing the cost
than the FCC noticing the signal<LOL> BUT either a yc156 or 179 with a
reasonable PS and close to a 100 watts drive will run the legal limit
with only a little overhead, but the tubes have outstanding IM
characteristics and should last forever.
## a 100 w of drive to a YC-156 will peg a 5 kw slug.
I have to admit, that even if all the drive you have available will just
give the legal limit, opening the hood to show off an amp that has a
tube with handles would be kinda good for the ego and it'll put out a
very clean signal. AND if you build it, there is absolutely nothing
illegal about it far as I can interpret the regs. So what if I had an
amp capable of 8000 watts out, if I had that much drive (I have
neither), in addition to the lack of drive
## Is ur xcvr qrp ? Just 50 w of drive = 1.5 kw... using a 3x3.
100w = 2.5 kw 150w = 3.5 kw 200w = 5.2 kw
## A YC-156/172 has way more gain than a 3x3. It needs very
little drive for 1.5 kw. QrP will almost do it.
I don't have an antenna on
the place that would handle much more than the legal limit...if that,
and a number that would be hard pressed to handle the legal limit in any
thing other than SSB.
## what's the ant problem ? You can't blow up a F-12 tribander,
nor a F-12 monobander. Mosely.... can't help there.
Nor do I have the coax connectors that would
handle that kind of power.
## Teflon /silver UHF connector's will handle loads of power....
more than an N. For max reliability, the 7-16 Din is the new standard.
So, sure I could put a yc-189 on and still
be legal as long as I didn't push the output into the illegal realm if I
haven't read the regs wrong.
## IMO... what diff does it make how one gets his ERP ?
Engineering, like all amp usually consists of a bunch of compromises.
Having been a project engineer I can appreciate the compromise angle
from both the engineers and management's perspective. It boils down to
selling not only what the customers want, but what the customers will
purchase. The automotive industry made the mistake of building what
people wanted, not what they'd purchase.
## Commercial amps... or HB.... huge difference. HB is like a
one off custom street rod... with minimal compromises.
With an amp, you have to build something that will deliver the desired
power, that is rugged enough to keep the complaints to a minimum, and
that includes the packaging. As for the ALC option, I haven't had an
amp in the last 20 years that did not have an alc line back to the
transmitter.
## good point on the ALC. It worked great 30 yrs ago on my drakes.
I have not incorporated it into any hb amps. You can internally set the
max power on the MK-V.. for 3 x diff menu pre-sets... with 3 x pots inside.
The 10-75-200 w settings can actually be set for anything from 0-200w.
We use the 75w one.. and tweak it a bit higher. Then, with front panel
power output floored, you can't over drive anything.
Some of todays not only have that, but those running AB1
have their own ALC. The solid state amps from a KW up tend to be a tad
pricey, but they have protective circuits, auto band switching, and ALC
that would have made manufacturers jealous 10 or 20 years ago. My old
Heathkit and Hallicrafters amps don't, or didn't even have an ALC
connector. IIRC my Dentrons didn't either, but I'd not guarantee that.
## The Array solutions wattmeters have both LO and HI power alarms
on em.. along with the SWR alarm. The HI power alarm would shut off
the amp, if over driven...and bring in yellow lights etc. You can shut down the
amp either via applying -vdc to alc buss on xcvr.... or opening off key
line...
or shutting off the xcvr via it's TX inhibit lead.
A couple of us "locals" were recently talking about building amps that
would be rugged, provide a reasonable overhead for reliability, and look
like it was built by some one who knew what they were doing. That meant
sending the panels out although we both have the capability and skill to
do the metal fabrication. BUT by the time we each purchased the parts
for a "one off" amp, including the panels we could get what we wanted
commercially for the same price or even cheaper than doing it yourself.
Now these are legal limit amps that could run digital at the legal limit
24 X 7 and although desktop I'd not call them either small nor light.
## for the $3-10K that they all want for an amp.... I can build
a better mouse trap..for way less. If 1-4 fellows settled on an identical
design, it would be even cheaper. Buy 4 of everything. A 46 lb dahl/harbach
hypersil would be a good start... get a deal on 4 x identical units. You need
HV lytics, I have case loads of em. 6A10 diodes, etc are chump change.
Do 4 x identical loads of metal work.... like a small production run [4].
Between A few of the excellent surplus places in holland, and Fair radio,
Allen Bond, E bay, SSON, Mouser, digi key, newark.. or just ask, and you will
have all the parts required. 2-4 guys can have one Hv supply put together
very quickly. The next 3 x supplies, you can do blind folded.
Just make sure you have all the tools, like the green lee punchs, and a
roper whitney hand and bench punch..... then you drill mimimal holes.
Greenlee now makes a combo drill/tap all in one. Take one one project
or aspect a day. Today we make diode boards.. bam , done, what's next?
Is it morning coffee break yet ? An extra pair of hands makes a huge
difference.
It's actually not a bad idea. Roger, I'll nominate you as project manager.
You
won't be able to keep your coffee warm on the tank coils though... they run
stone cold. I can see it now... start filling up bins with parts... what a
hoot.
Roger's garage gets turned into an amp factory.
later... Jim VE7RF
73
Roger (K8RI)
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