I purchased one of these amps about two years ago. I expected it to require
50 to 60 watts of drive for full output but it only took half that. I was
worried about screwing up and hitting it with 100 watts from the K3 and
blowing the final transistor. I knew there was a pad on the input and I
figu
For those who would like to go the attenuator route to allow the 100 W PA to
drive their amp at medium power, Phil Salas, AD5X, defined the parts for a
nice 2 dB attenuator in:
Aug 2010 - QST (Pg. 39)
Simplify Transceiver to Amplifier Interfacing with an In-Line Attenuator
Regards, Joel Hallas, W
With the KPA3A / 100 watt amp active, which switches in at 12 watts, the
LPA then runs about 1 to 5 watts. The issue I encountered was running
the KPA3A / 100 watt amp, at the lower end of the power range being 15
or so watts. I encountered two failures of the KPA3A amp module.
I now stay aw
Oh I just reread your post. My mistake. So running low power on the KPA is also
problematic?
Chuck Jack Hawley
KE9UW
Sent from my iPhone, cjack
> On Nov 21, 2019, at 10:32 PM, Bob McGraw K4TAX wrote:
>
> I learned my lesson running 12 to 15 watts or so having to replace the KPA3A
> twice.
I thought the answer was to run the KPA by going up to 12 or 15 watts. What is
the LPA running when when the power is at 12 or 15 watts? What is it running
when the power is at 20 or 25 watts?
Chuck Jack Hawley
KE9UW
Sent from my iPhone, cjack
> On Nov 21, 2019, at 10:32 PM, Bob McGraw K4TA
I learned my lesson running 12 to 15 watts or so having to replace the KPA3A
twice. I now run 20 to 25 watts driving my KPA500 to rated output. Be it CW,
SSB or digital modes. Otherwise it is 100 watts when not running the KPA500.
Running conservative power doesn't get it.
Bob, K4TAX
Sen
Makes you wonder how K3/10 users fair running high duty cycle modes at full
output. I’ve replaced two sets of LPF drivers running 10W WSJT on my K3/100. No
more! Now I advance the power until the amplifier engages (~12W). Hopefully
this reduces driver dissipation.
Dennis, K7FL
> On Nov 21, 2
Thanks for the good info Keith - I quit using 12w yrs ago as one E'craft
tech told me after the 1st one blew.
Also heard from another that I could turn the fans on all the time which
should help as normally they are only on when you go to 13w and up.
Will play with them - t u 73 Dwight NS9I
You can play with the Config Menu watt meter calibration high and low
numbers to get the switch-over point different.
IE where the Low power amp (LPA) switches to 100 amp (KPA3). This
happens at 12W "indicated".
The two Calibration numbers are for all bands!
So; Go into config menu WMTR LP (bel
I only work RTTY with 5 ... 8 W input from the K3S. That's enough.
73
Lutz, DL7UGO
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That is correct. The current FCC regulation requires that an amp be
limited to 15 dB of gain.
Therefore, 900 watts out with 11 watts of drive is 19.12 dB gain.
Even with 800 watts out and 11 watts of drive the gain would be 18.61
dB. Not exactly legal in the USA. dB = 10log(p1/p2) T
Yes, but, that also attenuates receive. I know, not much but I need
every fraction of a db on 80 and 160 for those weak ATNO's. Yes I know I
could switch one in/out but, remoting adds another can of worms,
especially when remoting.
I received some excellent advice from Fabio IK6ZER on the SPE
It would be more appropriate if SPE shipped their amplifiers to
the US with the proper (legal) attenuator in place. That way one
would be running the K3/K3s at 30 Watts in the first place.
73,
... Joe, W4TV
On 2019-11-21 10:42 AM, j...@kk9a.com wrote:
I have operated RTTY with my K3S in t
Why not add a 1 dB or 2 dB attenuator in line at the input of the amp?
That would allow for a bit higher drive power from the K3S. Three
carbon resistors will make a nice Pi attenuator.
73
Bob, K4TAX
On 11/21/2019 9:42 AM, j...@kk9a.com wrote:
I have operated RTTY with my K3S in the 11 wa
I have operated RTTY with my K3S in the 11 watt range not knowing that
this was bad for the LPAs. It would be nice if the Elecraft K3/K3S
would allow the option to turn on the 100 watt power amp and a lower
power setting.
John KK9A
dgb ns9i wrote:
I run a lot of rtty and digital with my K
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