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K1 AGC mod

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NZ0T

K1 AGC mod

I just built K1 SN 3353 and it's a neat little rig. I usually wear headphone so now that I've experienced the AGC lag I would like to do something about it. I know it's audio derived so it will never sound like a K2 or K3 but if I could reduce the loud spike at the start of a received transmission it would help. From perusing the net it looks to me like the most common mod involves replacing C31 on the RF board with a 1uf and C67 on the same board with a .22uf. Is this the best mod or are there others that I should look at?

73 Bill NZ0T

Myron WVØH

Re: K1 AGC mod

I would be interested in this too. Do you know of a web page that describes the mod?

Myron WVØH
Printed on Recycled Data

> On Feb 1, 2015, at 8:37 AM, NZ0T <[hidden email]> wrote:
>
> I just built K1 SN 3353 and it's a neat little rig. I usually wear headphone
> so now that I've experienced the AGC lag I would like to do something about
> it. I know it's audio derived so it will never sound like a K2 or K3 but
> if I could reduce the loud spike at the start of a received transmission it
> would help. From perusing the net it looks to me like the most common mod
> involves replacing C31 on the RF board with a 1uf and C67 on the same board
> with a .22uf. Is this the best mod or are there others that I should look
> at?
>
> 73 Bill NZ0T
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K1-AGC-mod-tp7597792.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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>
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> Please help support this email list: http://www.qsl.net/donate.html
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Phil Wheeler-2

Re: K1 AGC mod

In reply to this post by NZ0T

I believe there is a message in the list archives
from Wayne on this subject. But apparently this
was before the list archives started. About midway
down on this page is a relevant message from Wayne.

http://www.qsl.net/ve3mcf/elecraft_reflect/K1_AGC_Notes.txt

73, Phil W7OX

On 2/1/15 7:37 AM, NZ0T wrote:

> I just built K1 SN 3353 and it's a neat little rig. I usually wear headphone
> so now that I've experienced the AGC lag I would like to do something about
> it. I know it's audio derived so it will never sound like a K2 or K3 but
> if I could reduce the loud spike at the start of a received transmission it
> would help. From perusing the net it looks to me like the most common mod
> involves replacing C31 on the RF board with a 1uf and C67 on the same board
> with a .22uf. Is this the best mod or are there others that I should look
> at?
>
> 73 Bill NZ0T

NZ0T

Re: K1 AGC mod

In reply to this post by Myron WVØH

Here are a couple of places I have found something:

http://www.jl3amk.org/en/#k1_mods

The other one that I got the cap values from that are in my OP were from an
Elecraft reflector post by a ZL that I can't find now. I'm going have to
check my junk drawer and see if I have nay caps that will work.

73 Bill NZ0T

On Sun, Feb 1, 2015 at 9:53 AM, Myron WVØH <[hidden email]> wrote:

> I would be interested in this too. Do you know of a web page that
> describes the mod?
>
> Myron WVØH
> Printed on Recycled Data
>
> > On Feb 1, 2015, at 8:37 AM, NZ0T <[hidden email]> wrote:
> >
> > I just built K1 SN 3353 and it's a neat little rig. I usually wear
> headphone
> > so now that I've experienced the AGC lag I would like to do something
> about
> > it. I know it's audio derived so it will never sound like a K2 or K3
> but
> > if I could reduce the loud spike at the start of a received transmission
> it
> > would help. From perusing the net it looks to me like the most common
> mod
> > involves replacing C31 on the RF board with a 1uf and C67 on the same
> board
> > with a .22uf. Is this the best mod or are there others that I should
> look
> > at?
> >
> > 73 Bill NZ0T
> >
> >
> >
> > --
> > View this message in context:
> http://elecraft.365791.n2.nabble.com/K1-AGC-mod-tp7597792.html
> > Sent from the Elecraft mailing list archive at Nabble.com.
> > ______________________________________________________________
> > 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]
>

NZ0T

Re: K1 AGC mod

In reply to this post by Myron WVØH

Here is the other site:

http://mailman.qth.net/pipermail/elecraft/2005-May/044374.html

On Sun, Feb 1, 2015 at 9:53 AM, Myron WVØH <[hidden email]> wrote:

Don Wilhelm-4

Re: K1 AGC mod

In reply to this post by NZ0T

Bill,

Decreasing C31 may decrease the attack time, and decreasing C67 will
reduce the hang time.
If you are having trouble with the initial 'spike', then I would suggest
reducing C31 first.
You can experiment with the values.

Also take a look at Wayne's comments at
http://www.qsl.net/ve3mcf/elecraft_reflect/K1_AGC_Notes.txt and be sure
what you are hearing is not the audio 'thump'.

73,
Don W3FPR

On 2/1/2015 10:37 AM, NZ0T wrote:

NZ0T

Re: K1 AGC mod

Hi Don,

Thanks for your response. I'm sure it's not the "thump" but rather a spike
in the audio derived AGC before it reduces the the level. I'll try
decreasing C31 first

On Sun, Feb 1, 2015 at 3:51 PM, Don Wilhelm <[hidden email]> wrote:

> Bill,
>
> Decreasing C31 may decrease the attack time, and decreasing C67 will
> reduce the hang time.
> If you are having trouble with the initial 'spike', then I would suggest
> reducing C31 first.
> You can experiment with the values.
>
> Also take a look at Wayne's comments at http://www.qsl.net/ve3mcf/
> elecraft_reflect/K1_AGC_Notes.txt and be sure what you are hearing is not
> the audio 'thump'.
>
> 73,
> Don W3FPR
>
>
> On 2/1/2015 10:37 AM, NZ0T wrote:
>
>> I just built K1 SN 3353 and it's a neat little rig. I usually wear
>> headphone
>> so now that I've experienced the AGC lag I would like to do something
>> about
>> it. I know it's audio derived so it will never sound like a K2 or K3 but
>> if I could reduce the loud spike at the start of a received transmission
>> it
>> would help. From perusing the net it looks to me like the most common mod
>> involves replacing C31 on the RF board with a 1uf and C67 on the same
>> board
>> with a .22uf. Is this the best mod or are there others that I should look
>> at?
>>
>>
>>
>

NZ0T

Re: K1 AGC mod

In reply to this post by NZ0T

I found a 0.47uf cap in my junk box and replaced C31 with it. I've not had a chance to have a QSO yet but just listening around I hear a big improvement.

Thanks all for your comments!

73 Bill NZ0T