KX1 power output increase -- free mod kit available

[wayne burdick]

Some KX1s have slightly lower transmitter output than others. When  
using a 14V supply, the output may be as low as 2.5 to 3 watts across  
all bands instead of the expected 3 to 4 watts. When using the internal  
battery the output maybe as low as 0.75 to 1 watt instead of he  
expected 1 to 1.5 watts.

Some builders have noticed this effect only after installing the  
KXB3080 option (30/80 meter module). The low-pass filter module  
supplied with the KXB3080 has slightly different characteristics from  
the original, which is necessary to obtain coverage of all four bands.

If you think your KX1's output is on the low side, for whatever reason,  
you can order our model #KX1PWRMODKT at no charge. It's listed at the  
bottom of our Parts and Mod Kits page:

    http://www.elecraft.com/order_form_parts.htm

The mod kit provides two resistors and instructions, and the change is  
easy to make. If you have your own stash of resistors, you can just  
download the application note at:

     
http://www.elecraft.com/manual/ 
E740099%20KX1%20Application%20Note%20Rev%20A.pdf

NOTE: We don't recommend making the change if your KX1 already puts out  
4 watts or more on some bands. While it's generally safe to operate the  
KX1 at 5 watts, the design was optimized at the 4-watt level to provide  
plenty of safety margin in terms of RFI, current drain, and heat  
sinking via the top cover.

73,
Wayne
N6KR


---

http://www.elecraft.com

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[Ron D'Eau Claire-2]

Since someone already hollered privately and said, "That URL doesn't work!"

Note that most people will have to splice it together again! The long URL
gets broken in a lot of e-mail readers.

An alternative "TinyURL" that will take you to the same Elecraft document to
download/view the Application Note is:

http://tinyurl.com/rzp42


Ron AC7AC

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[Randy Rathbun NV0U]

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I have not opened mine up yet, but in looking at this I found a typo  
in the App Note....

it says "Locate resistor R30 on the bottom of the board between  
trimmer pot R30".... should that be R4?

Randy Rathbun NV0U
[hidden email]
K2#1981, kx1 #1318, ARS #895, QRPARCI #10776, FP#1292, KCQRP #1



On Apr 5, 2006, at 6:07PM, wayne burdick wrote:

> Some KX1s have slightly lower transmitter output than others. When  
> using a 14V supply, the output may be as low as 2.5 to 3 watts  
> across all bands instead of the expected 3 to 4 watts. When using  
> the internal battery the output maybe as low as 0.75 to 1 watt  
> instead of he expected 1 to 1.5 watts.
>
> Some builders have noticed this effect only after installing the  
> KXB3080 option (30/80 meter module). The low-pass filter module  
> supplied with the KXB3080 has slightly different characteristics  
> from the original, which is necessary to obtain coverage of all  
> four bands.
>
> If you think your KX1's output is on the low side, for whatever  
> reason, you can order our model #KX1PWRMODKT at no charge. It's  
> listed at the bottom of our Parts and Mod Kits page:
>
>    http://www.elecraft.com/order_form_parts.htm
>
> The mod kit provides two resistors and instructions, and the change  
> is easy to make. If you have your own stash of resistors, you can  
> just download the application note at:
>
>    http://www.elecraft.com/manual/E740099%20KX1%20Application%20Note 
> %20Rev%20A.pdf
>
> NOTE: We don't recommend making the change if your KX1 already puts  
> out 4 watts or more on some bands. While it's generally safe to  
> operate the KX1 at 5 watts, the design was optimized at the 4-watt  
> level to provide plenty of safety margin in terms of RFI, current  
> drain, and heat sinking via the top cover.
>
> 73,
> Wayne
> N6KR
>
>
> ---
>
> 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

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[Ron D'Eau Claire-2]

You are absolutely right. It is R4, not R30!

Ron

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Randy Rathbun NV0U
Sent: Wednesday, April 05, 2006 5:24 PM
To: wayne burdick
Cc: Elecraft Reflector
Subject: Re: [Elecraft] KX1 power output increase -- free mod kit available


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I have not opened mine up yet, but in looking at this I found a typo  
in the App Note....

it says "Locate resistor R30 on the bottom of the board between  
trimmer pot R30".... should that be R4?

Randy Rathbun NV0U
[hidden email]
K2#1981, kx1 #1318, ARS #895, QRPARCI #10776, FP#1292, KCQRP #1


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[Randy Rathbun NV0U]

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Just finished doing the mod here. I have some good news and some bad  
news....

Good news is it seems to have helped on 40/30/20. They are now 3 to 4  
watts out. Previously I was in the 2.5-3.0 range at best with just  
the 30 m module in, and was never able to get it above that area.

Bad news is the 80m won't go above 0.5 watts out. I fiddled with the  
toroid spacing and it did not seem to make any change.

Now, I could not wait to go to the local electronics store tomorrow  
so I just put another 10 ohm resistor in parallel with R11. I doubt .
3 ohms is gonna make that big a difference, so I aint worried there.  
I am curious though what others are seeing for output on 80? Starting  
to wonder if I have something wrong somewhere....

Randy Rathbun NV0U
[hidden email]
K2#1981, kx1 #1318, ARS #895, QRPARCI #10776, FP#1292, KCQRP #1



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[wayne burdick]

Randy,

If you're only getting 0.5 watts out on 80 m, it has nothing to do with
the two added resistors, and changing their values won't make any
difference. Most likely you have a toroid lead on the LPF1 module that
isn't making contact, or the relay on the module isn't getting turned
on when you switch to 80 meters.

73,
Wayne
N6KR

>
> Just finished doing the mod here. I have some good news and some bad
> news....
>
> Good news is it seems to have helped on 40/30/20. They are now 3 to 4
> watts out. Previously I was in the 2.5-3.0 range at best with just the
> 30 m module in, and was never able to get it above that area.
>
> Bad news is the 80m won't go above 0.5 watts out.

> ---

http://www.elecraft.com

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