Oh but contraire. I agree that lower dissipation typically reduces
MTBF. Therefore, never plug in your KPA500, leave it in the box and it
should last a very long time.
Sorry folks, I just couldn't resist.
I did not do extensive measurements, but the ones I did show the following:
450
Bionenne Power is a great source for batteries to do radio. You'll need
to find out the power requirements for you CPAP machine (voltage,
current, and duty cycle) to choose a battery pack for it.
73, Jim K9YC
On 2/9/2020 5:17 PM, Al wrote:
Greetings
I am looking for a battery pack for for
On 2/9/2020 1:20 PM, Dick Dickinson wrote:
Can a 2 conductor + shield cable be used on the K3 for Mic + PTT.share the
same ground..?
Yes, and they SHOULD share the same connection at the radio, to the CHASSIS.
73, Jim K9YC
__
Sounds as though the TR switching has failed. Contact Elecraft support.
Bob, K4TAX
Sent from my iPhone
> On Feb 10, 2020, at 5:05 PM, afpac...@gmail.com wrote:
>
> I am looking for thoughts and suggestions to diagnosis what I am seeing.
> When the amp is changed from STBY to OPER the
If there is a relay in the rx signal path, check the contacts. I had that
happen with my Alpha recently. Of all the possibilities that was the easiest
thing to fix. Thankfully that was the problem :-).
73,
Bill WE5P
Get BlueMail for Android
On Feb 10, 2020, 17:52, at 17:52,
Bill,
No relays in the T/R switching path for the KPA500 - all solid state
switching.
73,
Don W3FPR
On 2/10/2020 6:39 PM, Bill Weaver wrote:
If there is a relay in the rx signal path, check the contacts. I had that
happen with my Alpha recently. Of all the possibilities that was the
I hate texting. So inefficient. Take out the phone, put the reading glasses
on, yada yada.
Wonder if anyone has found a decent SMS to Morse app for Android? I've
looked in the google ply store and see one called SMS-Morse, but I haven't
tried it yet. Didn't really see any others that might fit
UPDATE:
Jack/W6FB contacted me directly shortly after posting. I sent him my fault
log to analyze and a detailed description of my equipment setup. Best guess
is a cable or antenna failure causing high SWR sometime in the recent past
that stressed the finals. They gave up the ghost when I was
I am looking for thoughts and suggestions to diagnosis what I am seeing.
When the amp is changed from STBY to OPER the receive signal drops by
multiple db and the general background seems to increase significantly. The
tuner seems to work the same with or without the amp. When I transmit it
It could be D36 & 37 on the RF board. Earlier ones (1st few thousand)
had weak components. But any of them can fail and usually there is
runaway power out.
If that is not it, look for burned components under the KANT3 board
around T4 or on the underside near D36 & 37 look for burnt traces.
If
If you notice a drop in signal strength when simply switching the amplifier
from "Standby" to "Operate", it means that the T/R diodes are biased for
transmit (not receive). Check R7 the 51 ohm SMD resistor on the daughter
board as the most likely failure. It has happened to me and several others
Andy,
Yes, you are right and this applies to both KPA 500 and KPA 1500.The
conditions for maximum efficiency are not necessarily those for minimum
dissipation or reduced stress.I would like to know if running 2/3, 1/2
or even 1/4 maximum power output increases reliability and MTBF.
https://youtu.be/AQdXQqZkIuk
-
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe: https://bit.ly/2FmwvDt
--
Sent from: http://elecraft.365791.n2.nabble.com/
__
Elecraft mailing
How you use your CPAP will have the biggest impact on your decision. Heat
and moisture adds a significant impact on the size of the battery. I would
also suggest two separate packs. This will guarantee you always have what
you need for your CPAP and may even have a back up. There are some nice
Doug,
"I would like to know if running 2/3, 1/2 or even 1/4 maximum power output
increases reliability and MTBF."
I have no experience of amplifier design but I would expect reliability of the
finals to depend on temperature. Finals temperature will depend on the power
dissipated in the
Hi Al,
We performed a series of tests to different battery types and
chemistries and have published the results here:
https://proaudioeng.com/portable-battery-performance/
The summary table is sortable for any parameter you are particularly
interested in. The Bioenno weighs in as a
We should also know the power supply efficiency though as a switcher, I expect
90 plus percent.73 Doug EI2CNSent from my Samsung Galaxy smartphone.
Original message From: Andy Durbin Date:
10/02/2020 16:58 (GMT+00:00) To: Doug Turnbull ,
elecraft@mailman.qth.net Subject: Re:
Hi,
I have a K3, and am seeing what looks to be some sort of unknown, and
unexpected AGC action when I have AGC off, on both the K3, and within
Windows.
I am trying to triage this to the radio, the computer, or WSJT-X.
Here are the test conditions:
WSJT-X used as the software for testing.
"This is probably what folks are thinking of when they assume maximum
dissipation occurs at less than full output."
A possible source of error in my data is that the dummy load is cool at the
start of the power ramp and hot by the time peak power is reached. I recorded
LP-100A data during
"I understand that efficiency decreases as one derates from the maximum of
1500W output.It surprises me that the power dissipated would peak at half power
output or 750 Watts."
I have no test data for the KPA1500 and will not speculate on the shape of the
PA dissipation curves. All I have is
Dear OMs, Maybe this is an advantage of the SPE 2KFA amp which has three power
levels 2000, 1200 and 600 W output. I have both amps and prefer the KPA 1500.
Which I find quieter both acoustically and RFI wise on RX. The KPA 1500 is
also happier handling Data modes. The SPE will drop down
Hello Andy,
I do not have the numbers and also would like them. I understand
that efficiency decreases as one derates from the maximum of 1500W output.
It surprises me that the power dissipated would peak at half power output or
750 Watts. This may be so.If so then almost certainly
One point to consider is the output network that is used to match the output
device impedance to 50 ohms. It is a fixed value or ratio. Thus if designed
for rated power then at 1/2 or 1/4 power the value would not seem to provide a
proper match for effective transfer of energy. This can
Several others have posted test data for the KPA500 here recently. As I
recall, it shows that dissipated power is fairly constant from about 50
percent to full output, at about 500 W, dropping a bit at lower power.
If it were an ideal class B amplifier, which no solid state RF amplifier
even
I would like to see the KPA-1500 have a "Medium Power" setting with optimized
bias for that power level so the amp could be operated at 750-watts output and
good efficiency. While the KPA-1500 can operate FT and RTTY contests at 1,500
watts, I believe the amp operated at 750-watts with an
Unless one is concerned about power consumption, the efficiency factor should
be really of no concern. Total heat output will always be greater at maximum
output and less at lower power. Nice for warming the shack on a Winter day.
Bob, K4TAX
Sent from my iPhone
> On Feb 10, 2020, at
Yes, I was wondering why this was so interesting.
Chuck Jack Hawley
KE9UW
Sent from my iPhone, cjack
> On Feb 10, 2020, at 12:47 PM, Bob McGraw K4TAX wrote:
>
> Unless one is concerned about power consumption, the efficiency factor should
> be really of no concern. Total heat output will
Thank you Andy,
Bob, if maximum power dissipation occurs at 50% max output power then the
greatest amount of heat should be generated for the shack at half max output
power. Power dissipation is in the form of heat not RF. The subject is
interesting for a number of reasons perhaps most
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