Elecraft

KPA100 Metering?

Classic

List

Threaded

5 messages Options

Fred (FL)

KPA100 Metering?

I saw a reference to a "wattmeter in the KPA100"?

Does the K2's "KPA100" option, include a wattmeter,
beyond what metering is now present in my K2's
relative reading LED multi-segment indicator?

What comes with the KPA100, in this area? If I
bought the KPA100 option, for my K2 - could I get
a accurate indication if I'm putting out 10watts,
38 watts or 100 watts? Or if the SWR presented to
the KPA100 is 1:1 or 11.6:1?

I'm really trying to decide whether to bite on
the KPA100 higher-power K2 option.

Thanks,
Fred N3CSY
....shores of St. Lawrence ...

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Tom Althoff

Re: KPA100 Metering?

Hi Fred -

There is wattmeter circuitry in the KPA-100 but the power display is scaled
to be shown on the 10 LED power indicator of the K2. Instead of each
segment representing 1W they are now 10W.

FYI...The KAT-100 auto-tuner provides LED bar display for SWR at points of
1:1, 1.2:1, 1.3:1, 1.5:1, 1.7:1, 2:1, 2.5:1, 3:1, 4:1 and 5:1.

- Tom K2TA
----- Original Message -----
From: "Fred (FL)" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, June 24, 2006 10:29 AM
Subject: [Elecraft] KPA100 Metering?

>
>
> I saw a reference to a "wattmeter in the KPA100"?
>
> Does the K2's "KPA100" option, include a wattmeter,
> beyond what metering is now present in my K2's
> relative reading LED multi-segment indicator?
>
> What comes with the KPA100, in this area? If I
> bought the KPA100 option, for my K2 - could I get
> a accurate indication if I'm putting out 10watts,
> 38 watts or 100 watts? Or if the SWR presented to
> the KPA100 is 1:1 or 11.6:1?
>
> I'm really trying to decide whether to bite on
> the KPA100 higher-power K2 option.
>
> Thanks,
> Fred N3CSY
> ....shores of St. Lawrence ...
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Ron D'Eau Claire-2

RE: KPA100 Metering?

In reply to this post by Fred (FL)

Fred N3CSY asked:
I saw a reference to a "wattmeter in the KPA100"?

Does the K2's "KPA100" option, include a wattmeter,
beyond what metering is now present in my K2's
relative reading LED multi-segment indicator?

What comes with the KPA100, in this area? If I
bought the KPA100 option, for my K2 - could I get
a accurate indication if I'm putting out 10watts,
38 watts or 100 watts? Or if the SWR presented to
the KPA100 is 1:1 or 11.6:1?

I'm really trying to decide whether to bite on
the KPA100 higher-power K2 option.

----------------------------------

Yes, the KPA100 includes a built-in directional coupler that monitors the
SWR at the output of the K2 instead of the simple RF Voltmeter circuit the
QRP K2 uses. The output of the directional coupler provides the ALC feedback
signal to keep the power level at the "requested" level set by the POWER
control. Also, in TUNE the K2 LCD displays the SWR at the output. In TUNE
the LCD will have a display something like 95 1.2 --1 indicating 95 watts
with an SWR of 1.2:1. The power is displayed using two digits, so it's to
the nearest watt above 10 watts and to the nearest 0.1 watt below 10 watts.
It works across the whole power range of the K2 whether the KPA100 is
enabled or not, as long as it's installed in the K2.

Accuracy? I haven't measured it closely. It depends upon how it's
calibrated. Mine is certainly within 10%, which I consider *great* for any
RF power meter.

Ron AC7AC

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-3

RE: KPA100 Metering?

In reply to this post by Fred (FL)

Fred,

Yes, the KPA100 (and the KAT2 and the KAT100) contain a directional coupler
type wattmeter to indicate the forward power and the SWR. These wattmeters
remove the necessity for operating the K2 into a 50 ohm non-reactive load in
order to obtain power accuracy. The forward power output of these
wattmeters is used to control the K2 power output as well as display it on
the LED (and on the LCD during TUNE).

These internal wattmeters need to be calibrated with some external reference
power metering if they are expected to be accurate. I measure the RF
Voltage across a 1% precision 50 ohm non-reactive dummy load for the
calibration, and I feel I can calibrate the wattmeter to within 5% using
that method. Many wattmeters available to hams are simply not that
accurate. Even the Bird specs its accuracy at 5% of full scale ONLY after
proper calibration - and with a 100 watt slug, that means the power reading
can be up to 5 watts off at any power level. Know your instruments and know
just how much to trust what they tell you.

73,
Don W3FPR

> -----Original Message-----
>
> I saw a reference to a "wattmeter in the KPA100"?
>
> Does the K2's "KPA100" option, include a wattmeter,
> beyond what metering is now present in my K2's
> relative reading LED multi-segment indicator?
>
> What comes with the KPA100, in this area? If I
> bought the KPA100 option, for my K2 - could I get
> a accurate indication if I'm putting out 10watts,
> 38 watts or 100 watts? Or if the SWR presented to
> the KPA100 is 1:1 or 11.6:1?
>
> I'm really trying to decide whether to bite on
> the KPA100 higher-power K2 option.
>
> Thanks,
> Fred N3CSY

Ron D'Eau Claire-2

RE: KPA100 Metering?

In reply to this post by Ron D'Eau Claire-2

One thing I overlooked about your question about SWR metering: it only
indicates the SWR up to 9.9:1.

Ron

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com