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[KX3] Power Consumption

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W0JFR

[KX3] Power Consumption

Trying to do some planning for Field Day battery operation. We are
planning to use a KX3 at 5w, CW.

Could someone(s) give me a feeling for RX current draw. I would like
this to be with the Backlight ON, and other normally ON functions
activated. Likewise, what current draw should we see with key down CW at 5w?

Thanks,
- 73, John, N0TA
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Don Wilhelm-4

Re: [KX3] Power Consumption

John,

The VFO B Altermate display when set for current will tell you that
information for your particular KX3.

The manual says receive current will be in the range of 150 to 200 ma.
and depends on backlight, preamp isolation amp and whether or not the
internal speaker is used.

I have not measured TX current at 5 watts, but I would expect somewhere
in the vicinity of 2 amps.

73,
Don W3FPR

On 1/9/2015 4:44 PM, Reilly, John wrote:

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wayne burdick

Re: [KX3] Power Consumption

Administrator

In reply to this post by W0JFR

With backlight on, RX current should be roughly 170 to 230 mA (no AF signal) depending on band.

TX current at 5.0 W should be about 1.0-1.4 A in CW/FM/FSK-D modes and 1.4-1.8 A in SSB/AM/PSK-D/DATA-A/AFSK-A modes. Actual current will vary with band and antenna load impedance.

The reason 5.0 W current drain is lower in CW/FM/FSK-D modes is that the KX3 uses its higher-impedance PA transformer winding at this level. The upper limit for use of the high-Z winding is 5.0 W in CW/FM/FSK-D and 3.0 W in all other modes. If you're above the limit for a given mode, the lower-Z winding is used to minimize transmit IMD at higher power levels.

73,
Wayne
N6KR

On Jan 9, 2015, at 1:44 PM, "Reilly, John" <[hidden email]> wrote:

> Trying to do some planning for Field Day battery operation. We are planning to use a KX3 at 5w, CW.
>
> Could someone(s) give me a feeling for RX current draw. I would like this to be with the Backlight ON, and other normally ON functions activated. Likewise, what current draw should we see with key down CW at 5w?
>
> Thanks,
> - 73, John, N0TA

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Bob N3MNT

Re: [KX3] Power Consumption

This simple response to a current requirement question is also a testament to the amazing design decisions used to make this little gem what it is. Designing products for a hobby you are passionate ( and participate) in produces amazing products.
Thanks Elecraft

Phil Wheeler-2

Re: [KX3] Power Consumption

In reply to this post by wayne burdick

Very cleverly done, Wayne:-)

Phil W7OX

On 1/9/15 3:26 PM, Wayne Burdick wrote:

> The reason 5.0 W current drain is lower in CW/FM/FSK-D modes is that the KX3 uses its higher-impedance PA transformer winding at this level. The upper limit for use of the high-Z winding is 5.0 W in CW/FM/FSK-D and 3.0 W in all other modes. If you're above the limit for a given mode, the lower-Z winding is used to minimize transmit IMD at higher power levels.
>
> 73,
> Wayne
> N6KR
>
>
> On Jan 9, 2015, at 1:44 PM, "Reilly, John" <[hidden email]> wrote:
>
>> Trying to do some planning for Field Day battery operation. We are planning to use a KX3 at 5w, CW.
>>
>> Could someone(s) give me a feeling for RX current draw. I would like this to be with the Backlight ON, and other normally ON functions activated. Likewise, what current draw should we see with key down CW at 5w?
>>
>> Thanks,
>> - 73, John, N0TA

NC3Z

Re: [KX3] Power Consumption

In reply to this post by W0JFR

Here are some numbers I measured, transmit was with a CW carrier:

TX Current

RX Current
Band 5W* 10W* 15W 20W 25W

With KXPA
60 1.17A 2.22A

20 1.20A 2.20A 7.75A 8.75A 9.50A
.200A .450A
10 1.40A 2.50A

* add .25A with KXPA on

Gary Mitchelson
NC3Z Davidsonville, MD FM18
NC3Z/4 Pamlico County, NC FM15
www.mitchelson.org

On 1/9/2015 4:44 PM, Reilly, John wrote:

> Trying to do some planning for Field Day battery operation. We are
> planning to use a KX3 at 5w, CW.
>
> Could someone(s) give me a feeling for RX current draw. I would like
> this to be with the Backlight ON, and other normally ON functions
> activated. Likewise, what current draw should we see with key down CW
> at 5w?
>
> Thanks,
> - 73, John, N0TA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]