Ha! I would venture to say that anyone that says they haven't done this
kind of thing would be fibbing. I've blown up lots of stuff:
* When I was in high school electronics class, I wired an AC power
switch in some long-forgotten transmitter in PARALLEL with the power
line instead of SERIES. Fuse? Nah.
* I built a Heathkit SW receiver. I swapped the germanium diodes for
the RF detector with the silicon diodes for the power supply
rectifier. This time there was a fuse.
* I've put many transistors in backwards. The transistors protect the
fuse.
* Many times I've tried to work the local repeater without remembering
to connect the antenna to the radio. I've done this both in mobile
and home stations. I've never blown a final, though.
* Another Heathkit was a vacuum tube voltmeter. I wired all of the
resistors on the 10 position range switch EXACTLY one switch
position off.
* I blew up a $200 LDMOS transistor for an HF amp. I recorded the
whole thing on video and posted it to YouTube. I STILL don't know
how or why the transistor blew. RF Parts was happy to sell me
another one though.
* I had an old pickup truck that I used only for snow plowing. Both
battery cables were black (don't ask why). Every fall I would put
the battery in to prepare for the season. EVERY fall I would hook
the battery cables up backwards. BZZZT!
* I built my own house while working 60 hour weeks at a two-way radio
shop. I did all the electric wiring in the house. The first circuit
I hooked up was for basement outlets. By mistake I used the cable
for the water heater for the outlet string. BANG! GFI outlets don't
like 240V.
That's just the electronic stuff I can remember right now. We had the
kitchen floor replaced THREE TIMES because the pipe for the
self-installed dishwasher leaked.
Don't feel bad.
-John NI0K
P.S. Many, many years ago there was an article in 73 Magazine written by
a ham claiming that being a klutz was his specialty. He gave lots of
examples, but the crowning one described how he put out a fire in his
car (which was in the driveway) with the liquid from his septic tank
that he happened to be pumping at the same time. I saved the article.
Every time I read it I get the giggles.
[email protected] wrote:
Thanks Michael, Andy, and all for the original thread. It made me focus on
proper use of my KPA500 which has really done a great job for me since I
acquired it and a KAT500 over the summer.
Retitled this message because I do not want to hijack/derail the original
conversation.
What I want to know... is there no repair for absent minded button pushing and
thoughtless antenna positioning?
So that I don't forget again... A hopefully instructional "mea culpa" follows:
I have been using the IC-7000 for 2M APRS ops with a Diamond VX2000 vertical.
Also have been experimenting with HF simplex D-Star and Free DV digital voice
recently. The KPA500 has been instrumental for DV ops because of recent
squirrely propagation...
Mistake 1: Over the summer, I forgot to shut down the packet ops and ground 6/2/440
tri-band antenna while using a "nearby" halo with 350 watts 6M DV. That blew
the 2M front end of the IC-7000. Matt at SARTS/ICOM in Michigan repaired it and I put
together a protection relay circuit to ground the vertical if I forgot again. That should
have solved the issue...
Mistake 2: A relay contact was faulty (and I did not test it properly) and a
month later, an adventure on 6M DV mode took the 7000 front end again! Matt was
kind about fixing it ...again...
Here I claim total stupidity along with absent mindedness - I rebuilt the protection
circuit, tested it, it "seemed" to work fine... but it failed again a month
later!
Mistake 3: Failed, because I had removed the dummy load and *forgotten* to
replace it along with a key ground strap, which again left the receiver 2M
front end exposed. Kindly, Matt agreed to fix the 7000 a 3rd time...
The 7000 will not go back into service until I have completely re-arranged the
station set up because, to top off this comedy of errors... I totally ignored
one basic issue:
Original Mistake: the vertical and halo antennas were mounted on the same mast because "I
never planned" to use them at the same time. This is where stupidity/laziness compounded with
my absent minded operating practices to create the "perfect storm". Until I started using
the KPA500, the halo antenna field strength was not such that the 7000's 2M receiver section was
stressed by the signal strength from vertical, so I got complacent. Add in the KPA500 and smoke is
let out of Q551 in the IC-7000.
I am *sure* that no one on this group does this sort of sloppy engineering,
but let it serve as a not-so-subtle reminder that a station layout should not
be organically grown, but should be planned carefully with this sort of
damaging interaction in mind. Enjoy the laugh at my expense.
KD4IZ
Jack Spitznagel
FM19oo
-----Original Message-----
From: Michael Walker<[email protected]>
Sent: Monday, November 19, 2018 19:52
To: ANDY DURBIN<[email protected]>
Cc: [email protected]
Subject: Re: [Elecraft] Killed the KPA500 :)
Knowing what I did while transmitting at 100 watts of msk144, I’m surprised the
damage isn’t worse.
The protection circuits did the best they could of.
If you own any amp, you always need to be aware of the risk. I would never rely
on the automation to 100% protected any amp.
If you are worried about your amplifier and anyway I highly recommend you have
checklist handy every time you turn it on and change Bands. Never depend on the
protection circuits.
I know I’m preaching to the choir too many people, however it is imperative you
understand exactly how your amp works, how it’s wired, and how it interfaces
with any HF radio.
Mike va3mw
Sent from my iPad
On Nov 19, 2018, at 6:45 PM, ANDY DURBIN<[email protected]> wrote:
"The support team at Elecraft got back to me and the required parts to repair the
board are on the way. Nice job guys."
But the question remains - Why didn't the designed-in protections work? This
new KPA500 owner would appreciate an answer from Elecraft.
Andy, k3wyc
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