I Shot A Query Into The Net (fwd)
K8DO at aol.com
K8DO at aol.com
Mon Dec 11 14:47:22 EST 1995
I feel that this has relevance to this reflector... Denny
>Poem by Gail Barnes
>=============================================================
>>>
>>> I Shot A Query Into The Net
>>>
>>> I shot a query into the net.
>>> I haven't got an answer yet,
>>> But seven people gave me hell
>>> And said I ought to learn to spell;
>>>
>>> A posted message called me rotten
>>> For ignoring mail I'd never gotten;
>>> An angry message asked me, Please
>>> Don't send such drivel overseas;
>>>
>>> A lawyer sent me private mail
>>> And swore he'd slap my ass in jail --
>>> I'd mentioned Un*x in my gem
>>> And failed to add the T and M;
>>>
>>> One netter thought it was a hoax:
>>> "Hereafter, post to net dot jokes!";
>>> Another called my grammar vile
>>> And criticized my writing style.
>>>
>>> Each day I scan each Subject line
>>> In hopes the topic will be mine;
>>> I shot a query into the net.
>>> I haven't got an answer yet ...
>From aa4lr at radio.org (Bill Coleman AA4LR) Mon Dec 11 19:00:11 1995
From: aa4lr at radio.org (Bill Coleman AA4LR) (Bill Coleman AA4LR)
Date: Mon, 11 Dec 1995 15:00:11 -0400
Subject: Amplifier failures Summary (LONG)
Message-ID: <v01520d08acf227e34c63@[206.28.194.40]>
A short while ago, I asked about amplifier failures during contesting. I
remarked that there seemed to be an inordinate number of failures,
especially considering that a few watts out of a thousand or so won't make
much difference, but the consequence of losing the amplifier and having to
go barefoot is a considerable difference.
Not owning an amplifier, I solicited comments from the contest reflector.
I'll summarise the responses as follows:
10 Marginal amplifiers (poor designs, thermal problems, high duty cycles)
9 Operating abuse (out of tune, improper antenna, guest operators, too much
power)
2 Attrition
2 Never happens
1 Environmental
So, it would seem the concensus is that many amatuer amplifiers are
somewhat marginal in contest use, especially with regard to high duty
cycles found in contesting. Extra cooling apparatus would seem to be
appropriate, or more robust amplifier designs. Of course, simply slacking
off on output power would help, too.
A sizable number pointed out operational errors or abuse, especially in
guest operator or multi-operator stations. Unfamiliar equipment coupled
with fatigue is bound to result in these mistakes -- so this makes sense.
Station designers who expect guest operators should take this into account.
Perhaps it is best to design the station so that the correct antenna is
always chosen, non-tune amps, etc, and these errors would not occur.
Sometimes the amps wear out, and some lucky contesters have never witnessed
a failure.
Enjoy!
Here are the edited replies:
------------------------------------------------------------------------
From: Pete Smith <n4zr at ix.netcom.com>
My personal hunches (based on some limited guest op experience with SB-220
and TL-922) are:
duty cycle (Press F1 again, Floyd!)
haste (mistuning, overdriving, unnoticed antenna or feedline failures,
connecting to the wrong antenna. etc.)
------------------------------------------------------------------------
From: Jay Kesterson <jayk at bits.fc.hp.com>
Lots of amps are marginal at 1500w. You frequently don't find out how much
your amp can take till it breaks :-). Then you get smart and don't run a
SB-220 quite as hard. This is the reason that Alphas are so popular with
contesters. My Alpha 76PA has been putting out legal limit for 15 years of
contesting/DXing/etc.
------------------------------------------------------------------------
From: rossi at VFL.Paramax.COM (Pete Rossi)
I had a tube fail about 2 hours into this past CQ WW contest. I can't complain.
The tube was 25 years old!! My Heath SB-220 (build in 1970) still had it's
*original* tubes in it (3-500z). BTW, the tube failed during power-on after
I had to shut down for a short while about an hour into the contest. When I
returned, an hour later, the amp went >pfzzzz< when I turned it back on.
After I realized what the problem was (grid-to-filament short) I simply
removed the bad tube and ran the rest of the contest with only *one* 3-500Z
in the amplifier .. instead of two. So my signal was down 3dB.. never
really missed it.
When you do get your amp, go for one with 3-500Z's in it. I think these
other fancy tubes are simply too fragile. I have heard too many horror
stories of one minor tuning mistake ruining the tube in seconds..
------------------------------------------------------------------------
From: PEMS_ST_DK at noeca.ohio.gov
As one who has operated from maultis and loaned amplifiers to multis I can
comment. None of my amps (sb221 and Alpha 76pa ) has efver failed AT HOME.
When people operate at a multi they are not familiar with station equipment,
layout and tuning. This causes most fialures I believe.
Many amps do not have adequate heat removal systems and that ove time
causes component failure. Then their are power surges, outages, etc.
Also, remember you're hearing the worse for the most part here. Many of use
dont note that we had no failures (no news is good news?)
So, hey, my sb221 was driven hard by many and never died-I sold it to K3LR who
used it on 15 and had a parisitic problem-but I believe is fixed.
I now have a 3 holer Alpha 76 that I drive at 60 watts for limit out-no
problems.
Now, if were are talkin Dentron-well thats a whole different story!!!!
------------------------------------------------------------------------
From: mwollnnn at colybrand.com (Marty Woll -- BA - Honolulu )
At my QTH, where we did CQWW Phone multi-multi as WH6R, we used -
for the most part - a "fleet" of aging Henry 3-KAs (2 x 3-500Z).
After Dave N6DLU went through them pulling out bad components
(mainly the p.s. chokes), we decided to run them all in the CW
position (i.e., at the lower plate voltage), reasoning that we'd
do better with 800-1000 watts for 48 hours than we would with 1500
watts for 3 hours and barefoot the rest of the contest. (Sound
familiar?) While the extra watts might have made the difference on
a few missed QSOs or mults, esp. on the lower bands, we had no
failures or even hiccups from these old amps for the entire
weekend.
I have some ideas about causes for some of the amp failures:
1) Like a lot of amateur gear, many amps are designed more for
selling features and for price than for commercial - level
reliability. Thus, power supply components, cooling systems, etc.
may in fact be marginal for contest duty.
2) A lot of gear out there is probably like mine: aging. Many
components have limited shelf (or installed) lives, and
deterioration from heat, humidity (esp. in Hawaii, the Caribbean,
and the humid Southeast), ozone, dirt, etc. will eventually cause
failure of components and interconnections.
3) We tend to subject our gear to physical wear and environmental
risks which can shorten the mtbf: jostling it around as we move it
from place to place; inducing thermal stress frequently by
turning it on and off a lot; not providing a "conditioned" ac line
for amplifiers as we might for lower-drain station components;
hot-switching the relays by use of vox or voice / code generators
without proper sequencing or timing; transmitting into incorrect
(or no) antennas due to switching errors; and failing to perform
preventative maintenance.
------------------------------------------------------------------------
From: Robert <w5robert at blkbox.COM>
When your in competition, it's difficult to reach up there and say:
OK 1200 PEP. Even more so if your out on expedition and you know if
the amp. goes south that there are no spares around. Sometimes you
just say go for it and see if your equipment does it. Depends are
what your doing, I guess.
------------------------------------------------------------------------
From: Gary Nieborsky <k7fr at ncw.net>
Woeful as it seems, driving them to destruction seems to be the fate de jure
for contest amps. I run a Kenwood TL-922 and have not had any problems.
The Conventional Contest Wisdom (CCW, hey maybe that explains it!) is that a
922 is a junker that has no business transmitting signals in the same ether
as an ETO. From observation I'd say that any good 1kW ether burner is good
as long as the transformer can handle the load and there is sufficient
cooling. One draw back with the 922 is that you need to prop it up on 2x4's
to gain a little better cooling flow. It's kept mine going for 7 contest
seasons.
------------------------------------------------------------------------
From: W8FJ at aol.com
24 years ago I purchased and built a Heathkit SB220 amplifier. It's output
is about 800W max, but it's stood me in good stead for all these years. Yes,
it did fail, for the first time 2 years ago. I sent it back to Heath for an
overhaul. It's back home and running strong, and who knows, it just might go
for another 22 years before hicupping again. Talk about money well spent!
------------------------------------------------------------------------
From: "sellington" <sellington at mail.ssec.wisc.edu>
While there ARE some marginal amplifiers out there, I expect most of
the contest failures are due to operator error. Even a rugged, well
designed amplifier running at 1.5 KW can be severely stressed by any
one of a number of common errors. Probably the most common is
transmitting into the wrong antenna, which we've probably all done a
few times. Another is a change in load with frequency. I doubt if
many of the failures result from trying to squeeze the last Watt out;
a properly loaded amplifier may see less stress at 1.5 KW out than
an improperly loaded one at 1.2 KW. Perhaps inadequate ventilation is
another factor.
In any case, I think a little care with one of the well-designed
commercial amplifiers can result in years of trouble-free contest
operation. I rebuilt an old SB-220 about 5 years ago with a few minor
improvements like bigger rectifiers and a second fan over the plate
transformer. One new tube developed a grid-cathode short early on
(under warranty), but otherwise it's been reliable. I put a temperature
sensor on the plate transformer, which tells me it probably wouldn't
survive continuous CQing for 48 hours, but I've never been able to keep
a run going long enough to overheat it.
So, as long as you're not trying to get 1.5 kW out of a pair of 811's or
a single 3-500Z, I think there's a good chance of trouble-free operation
with an amplifier. No guarantees, though.
------------------------------------------------------------------------
From: Steve Merchant <merchant at crl.com>
In my somewhat limited experience with multi's, I would have to say it is
more often that the amp fails in a multi, rather than single op, unless
there's a guest op.
Many times amps go because people hot switch them one too many times, or
operate them into open feedlines, or fire up with the bandswitch on the
wrong band. And you know how folks like to keep going <rate,
rate,rate!!!> despite loud warnings from equipment to the contrary.
I have an Alpha 76PA that is 20 years old now, still has original tubes
in it, and looks pretty much like it did when I bought it from ETO.
However, I've only used it in a very few multi situations. And on one of
those occasions, one of the other ops managed to smoke some diodes and
generally abuse it. I sent it back to ETO and they repaired it under
warranty. That was in 1977 or 78, and I learned my lesson.
At AG6D, we have seen three amps go within 3 qso's of each other --
mostly from marginal equipment conditions (ailing bandswitches) combined
with a guest op unfamiliar with the subtleties of tuning an amp that's not
feeling well.
The 87A makes a good amp in this situation provided it's looking at nice
flat feedlines, because there aren't any knobs or switches to fool with
-- you just adjust drive for the red light and go.
------------------------------------------------------------------------
From: KE5FI at aol.com
Well, I think "balls to the wall," lights dimming, transformer humming,
meters pegging power out is a real thrill....
...to a dummy load, of course!
------------------------------------------------------------------------
From: n0dh at comtch.iea.com
More than likely a little of both, I dont think some of the manufacturers
would consider sending "CQ TEST" for 48 hours without stopping ICAS!
Bill, where is it written that contestors are blessed with large doses of
common sense. Who in their right mind would put themself through 48 hours
of constant CW or scream QRZ TEST into a mic for two days. Who in their
right mind would spend $1,000 upon $1,000 of dollars, risk life and limb
putting over sized antennas on over tall towers just for the privilage of
sitting up 48 hours in a bad chair to work DX.
I was bitten by the contest virus almost 35 years ago when I entered my
first novice roundup. I never got over it. Which is why I've spent at least
10 hours a week for the last 2 months upgrading my 160 station.
------------------------------------------------------------------------
From: George McCrary <geo at nando.net>
AA4LR Wrote:
>it takes 1 dB of power change to make a perceptable difference, and that
>1500 W PEP is just that
I think you'd be REALLY hard pressed to see a difference with a mere
1 dB. Remember that 1 S unit is an entire 6 dB, and many times it's hard to
notice a fade from say S9 to S8!.
---
AA4LR Replies -
George, note that I said PERCEPTABLE difference. 1dB is just barely
perceptable. Human perception works on a logarythmic scale.
---
The other thing that I've been led to believe is that a lot of these
guys run 2K to 5K. I don't know if that's true, but it certainly seems
plausible.
------------------------------------------------------------------------
From: "Dick Dievendorff" <dieven at almaden.ibm.com>
I drive my Ameritron AL-1200 at 1500 watts or less.
What has "blown up" is the (optional add-on) pin-diode QSK arrangement that
went due to high SWR, probably caused by switching to the wrong antenna or
keying the rig and amp with no antenna because of some mistake in the antenna
switching arrangement.
Since the QSK board was inside the amplifier, I had to turn off the amplifier,
open it up, wire around the QSK board, and close up the amp. I've had to do
this three or four times in contests. I've since stopped trying to use this QSK
arrangement.
The resistor in my amp's parasitic suppressor has smoked a couple of times. At
1200 watts, not >1500. I think this is probably a design problem with the amp
(it seems to be a 10 meter problem). I eventually replaced the entire
suppressor, and I noticed at Dayton that Ameritron has redesigned the
suppressor since I replaced mine.
None of my failures have been caused by trying to get more than 1500 watts out
of the amp. They are caused by other abuse: operator mistakes. Some amps
don't have a lot of reserve or self-protection for mistuning or high SWR.
The increased duty cycle of contest operation coupled with operator fatigue,
trying to do things in a hurry, operators unfamiliar with the station switching
arrangement, other operator error, and the fact that many amps lack
self-protective circuitry has been the cause of all my amplifier failures.
If my exciter didn't turn down its output power in the presence of high SWR and
protect itself, I'd have more failures there.
It is for these reasons that I plan to replace my amplifier with one that is
more forgiving of my mistakes.
------------------------------------------------------------------------
From: K8DO at aol.com
You are correct in your analysis of the meaning of a 1 dB change...
Unfortunately, many hams do not comprehend that fact.. If they see the
needles swinging hard, and smell hot paint from the transformer, then they
think they are king kong on that band...As a result, their consumer grade
(i.e. built to a price range) amp goes down, valiantly... but down, non the
less... Those pampered amps, when subjected to a 36 or 48 hour grind, build
up heat in the transformers and filter caps, which are designed only for
short transmit cycles with long cool down periods, and eventually fail...
Usually, the tube is not the limiting factor in an amp... It is the power
supply, the air flow system, and the tank circuit,...
For contesting, that average amp needs some help... extra air flow, usually
an upgrade on the hv rectifiers/caps, as a bare minimum if it is going to
survive, even at the kw level...There are any number of articles on upgrading
of amps, esp. the ubiquitous SB220... These make a fine amplifier when
suitably upgraded...
I am currently running the Henry 3K Ultra...It weighs 380# !! It uses the
3CX1200 tube, which is not a super power tube...All that beef is in the items
that count... The 90# hv transformer... the inrush limited 25# filament
transformer / the 8 quart, oil filled, filter cap / the heavy tubing and
beefy tuning caps in the tank / the 2 speed, centrifugal blower that would
ventilate a house....It is not intended to be a super amp... It IS intended
to be a 1500 watt continuous service amp....All this, of course, costs
money...My shack is the culmination of 35 years of hamming and did not happen
overnight... and yes, I did operate for years with a beefed up SB220, and I
was careful to limit that last few hundred watts of output, and it survived
happily...
Now, if I were only younger and capable of performing as well as the gear I
have.. :)
So, find a buy in an older amp, upgrade it and contest happily, at a
reasonable power level..
------------------------------------------------------------------------
From: beaton at wintermute.co.uk (Alastair Beaton)
Having successfully "smoked" several amps during contests, I have a "noted
interest" in comments posted on the reflector regarding "big bang" theory!
One possible reason is that whereas a few years ago most mere mortals ran a
set-up with only the rig's own fist mike, the rig and the linear, nowadays a
typical contest station will have a mike with one of those groovy Heil
inserts, lots of processing and perhaps DSP.
Therefore the "average" (RMS?) power will be considerably greater, putting
greater demands on the power supply. Amps with "HI/LO (SSB/CW)" switches
which throw a couple of hundred more volts at the anode would therefore be
running under greater load than their makers intended. Also, the Cluster now
means that more of us pick a frequency at the start of acontest and bellow
continuously for 48 hours, pausing only for a fast QSY to pick up the Mults
- spending less time H&P'ing with the amp off-line.
The solution might be to leave amps on "LO" HT...
------------------------------------------------------------------------
From: Rick Niswander <AONISWAN at ECUVM.CIS.ECU.EDU>
I have never had an amplifier fail on me in a contest (back when I
was running one). In fact, I have never had a major failure of any kind.
------------------------------------------------------------------------
Bill Coleman, AA4LR Mail: aa4lr at radio.org
Quote: "The same light shines on vineyards that makes deserts." -- Steve
Hackett
>From k3ww at fast.net (Charles Fulp) Mon Dec 11 20:05:46 1995
From: k3ww at fast.net (Charles Fulp) (Charles Fulp)
Date: Mon, 11 Dec 1995 20:05:46 +0000
Subject: K3WW 10 Meter effort
Message-ID: <199512112004.PAA07413 at nn.fast.net>
ARRL 10 METER CONTEST -- 1995
Call: K3WW Section: EPA
Category: Multi K3WW+packet
Power 1500 W (frequently less)
MODE QSO QSO PTS STATES COUNTRIES
CW 303 1220 32 14
SSB 257 514 32 9
-----------------------------------------
Totals 560 1734 64 23 = 150,858
My best effort in a 10 meter contest that I can recall! Definitely
the most time on the air in one of these. CT says 17 hours of
operation, using 1/2 hour time offs. I was in and out of the
shack all weekend, the early hours were like a FRC/PVRC/YCCC QSO
party. KM9P was heard more frequently than any other distant
station. I chased some packet spots, and was tempted away after
a few hours, to chase some 160 stuff.
If you were watching Packet, you were simply MULTI OP in this one,
no Low power, High power or QRP or single mode, just Multi OP. Saw
a station spot himself as /QRP , so I questioned the practice to another
packet user.
His take was that the guy might be QRP and just fooling around, one
thing led to another and he suggested that a "just fooling around"
class might be good. Might be the best class of all, NO rules, make
all the points you can and send them in to be listed in the JFA class.
I enjoyed K3ZO's wrap up...I guess the guy that was loud when he sent
my call twice then disappeared completely the first time he sent
his call was a meteor scatter QSO, and the run of MO and AR stations
with not a single Texan to be heard was sporadic E. Pretty neat.
Interesting to see who could hear what this weekend, and I don't think
I got caught being in another contest.
73 Chas k3ww at fast.net
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