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KBPF3 upgrade kit and instructions now available

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wayne burdick

KBPF3 upgrade kit and instructions now available

Administrator

Hi all,

The long-promised KBPF3 modification kit is now available. It applies to the KBPF3, K3 RF board, and optionally to the KRX3 sub receiver. It allows the K3 or K3S to receive signals in the 100-500 kHz range with good sensitivity. This is an interesting part of the spectrum, with

For full details on the mod kit, see:

http://www.elecraft.com/order_form_parts.htm#K3%20Parts

Also see below for an excerpt from my original posting about signals in the 100-500 kHz range.

73,
Wayne
N6KR

* * *

In honor of the FCC's proposed "2200 meter" allocation (137 kHz), we decided to see if we could improve the K3's receive sensitivity in the 100-500 kHz range. This extended coverage is made possible by the new synth (KSYN3A).

After a lot of digging, we discovered the cause of the wide-band low-frequency noise. We also found a way to shift the passband of the KBPF3 lower.

With a couple of simple modifications, the MDS (minimum discernible signal) can be improved by about 25 dB at the low end (100 kHz). Here are some test results (preamp off, 400-Hz bandwidth):

137 kHz -114 dBm FCC's proposed 2200 meter band
160 kHz -117 dBm low end of the "Low-Fer" band
250 kHz -126 dBm test frequency in the long-wave beacon band
472 kHz -133 dBm 630 meter experimental band

This represents an improvement throughout the range, but especially at the low end. I believe -114 dBm MDS should suffice at 137 kHz, given the high band noise in this range.

Another indication of how well the mods work: With no antenna connoted, the K3's S-meter now just barely flickers (S1) at 100 kHz. Without the mods, the no-antenna S-meter reading could be as high as S7 due to the noise source we've now identified (a voltage regulator). (By the way, this regulator noise had no impact on frequencies about about 500 kHz.)

...

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Joe Subich, W4TV-4

Re: KBPF3 upgrade kit and instructions now available

Neither the instructions nor the errata speak to the regulator bypass
in the KRX3. The "instructions" do not provide information in either
bypass.

73,

... Joe, W4TV

On 2015-06-24 8:42 PM, Wayne Burdick wrote:

> Hi all,
>
> The long-promised KBPF3 modification kit is now available. It applies to the KBPF3, K3 RF board, and optionally to the KRX3 sub receiver. It allows the K3 or K3S to receive signals in the 100-500 kHz range with good sensitivity. This is an interesting part of the spectrum, with
>
> For full details on the mod kit, see:
>
> http://www.elecraft.com/order_form_parts.htm#K3%20Parts
>
> Also see below for an excerpt from my original posting about signals in the 100-500 kHz range.
>
> 73,
> Wayne
> N6KR
>
>
> * * *
>
> In honor of the FCC's proposed "2200 meter" allocation (137 kHz), we decided to see if we could improve the K3's receive sensitivity in the 100-500 kHz range. This extended coverage is made possible by the new synth (KSYN3A).
>
> After a lot of digging, we discovered the cause of the wide-band low-frequency noise. We also found a way to shift the passband of the KBPF3 lower.
>
> With a couple of simple modifications, the MDS (minimum discernible signal) can be improved by about 25 dB at the low end (100 kHz). Here are some test results (preamp off, 400-Hz bandwidth):
>
> 137 kHz -114 dBm FCC's proposed 2200 meter band
> 160 kHz -117 dBm low end of the "Low-Fer" band
> 250 kHz -126 dBm test frequency in the long-wave beacon band
> 472 kHz -133 dBm 630 meter experimental band
>
> This represents an improvement throughout the range, but especially at the low end. I believe -114 dBm MDS should suffice at 137 kHz, given the high band noise in this range.
>
> Another indication of how well the mods work: With no antenna connoted, the K3's S-meter now just barely flickers (S1) at 100 kHz. Without the mods, the no-antenna S-meter reading could be as high as S7 due to the noise source we've now identified (a voltage regulator). (By the way, this regulator noise had no impact on frequencies about about 500 kHz.)
>
> ...
>
> ______________________________________________________________
> Elecraft mailing list
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>
> 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]
>

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wayne burdick

Re: [Elecraft_K3] KBPF3 upgrade kit and instructions now available

Administrator

In reply to this post by wayne burdick

Looks like the wrong instruction sheet was linked to the order page. We'll get this updated ASAP and will post when it has been corrected.

Wayne

On Jun 24, 2015, at 5:42 PM, Wayne Burdick [hidden email] [Elecraft_K3] <[hidden email]> wrote:

> Hi all,
>
> The long-promised KBPF3 modification kit is now available.

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Phil Wheeler-2

Re: [Elecraft_K3] KBPF3 upgrade kit and instructions now available

But the errata is sure intriguing, Wayne :-)

73, Phil W7OX

On 6/24/15 6:15 PM, Wayne Burdick wrote:

> Looks like the wrong instruction sheet was linked to the order page. We'll get this updated ASAP and will post when it has been corrected.
>
> Wayne
>
>
> On Jun 24, 2015, at 5:42 PM, Wayne Burdick [hidden email] [Elecraft_K3] <[hidden email]> wrote:
>
>> Hi all,
>>
>> The long-promised KBPF3 modification kit is now available.

Michael Eberle

Re: KBPF3 upgrade kit and instructions now available

In reply to this post by wayne burdick

Will new orders for the KBPF3 have the modification already done or
would one need to purchase both the KBPF3 and the KBPF3MDKT if they
wanted to receive 100-500 kHz?

Mike
KI0HA

On 6/24/2015 7:42 PM, Wayne Burdick wrote:

wayne burdick

Re: KBPF3 upgrade kit and instructions now available

Administrator

On Jun 24, 2015, at 9:23 PM, Michael Eberle <[hidden email]> wrote:

>
> Will new orders for the KBPF3 have the modification already done…

Yes. That's the KBPF3A.

Wayne
N6KR

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Joe Subich, W4TV-4

Re: KBPF3 upgrade kit and instructions now available

However, if you are installing a KBPF3A in an existing K3 you
will still want to add the bypass capacitors to the regulators
on the main board and in the KRX3 if installed.

73,

... Joe, W4TV

On 2015-06-25 12:34 AM, Wayne Burdick wrote:

>
> On Jun 24, 2015, at 9:23 PM, Michael Eberle <[hidden email]> wrote:
>
>>
>> Will new orders for the KBPF3 have the modification already done…
>
> Yes. That's the KBPF3A.
>
> Wayne
> N6KR
>
>
>
>
> ______________________________________________________________
> 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]
>