[K3] LPF DSP modification

[K2QI]

Just saw that Elecraft is now offering a DIY kit to upgrade your current DSP
board with the LPF module.  This is a good option as the current exchange
program is taking waaay too long.  I was on the list to receive an upgraded
board since early December and still nothing.  I finally decided to take
myself off the list, and I think I'll pursue the DIY option instead.

Anyway, just going over the instructions and I'm curious as to how you guys
that have done this mod have gone about cutting the two traces?  Would an
exacto knife work?

73 de James K2QI

P.S.  Hope you all had fun during this weekend's ARRL DX contest... I
participated just for fun and was able to bag a few countries I didn't have
before.
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[Don Wilhelm-4]

Just take the tip of a knife blade and cut a "V" notch through the PC
board trace.  You do have to apply some pressure to the blade to get
into the fiberglass material and through the solder mask.  Use whatever
knife you are comfortable with, but it should be sharp.  I usually use a
utility knife or my pocket knife.  Do make sure it is sharp, a dull
knife can slip when pressure is applied, and we don't want any injuries.

73,
Don W3FPR

K2QI wrote:

> Just saw that Elecraft is now offering a DIY kit to upgrade your current DSP
> board with the LPF module.  This is a good option as the current exchange
> program is taking waaay too long.  I was on the list to receive an upgraded
> board since early December and still nothing.  I finally decided to take
> myself off the list, and I think I'll pursue the DIY option instead.
>
> Anyway, just going over the instructions and I'm curious as to how you guys
> that have done this mod have gone about cutting the two traces?  Would an
> exacto knife work?
>
> 73 de James K2QI
>  
>

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[Joe Planisky]

Hi James,

I used an Exacto knife to cut the traces on mine.  They're pretty thin  
lines, so it doesn't take much to cut through them.

Do note that the LPF mod does NOT give you the extended low frequency  
response on TX and RX that you would get with the board exchange.  If  
that's not important to you, then the DIY option is a good way to go.

Someone recently mentioned that Elecraft offered to modify his DSP  
board if he sent it in and that the turn-around time was just a few  
days.  Don't know if that's something they're generally offering or if  
it was a one-time-only deal for him.  The downside is you're without  
your K3 for the time it takes to get the modified board back to you.

73
--
Joe KB8AP

On Mar 8, 2010, at 7:47 AM, K2QI wrote:

> Just saw that Elecraft is now offering a DIY kit to upgrade your  
> current DSP
> board with the LPF module.

> ...
> I'm curious as to how you guys
> that have done this mod have gone about cutting the two traces?  
> Would an
> exacto knife work?
>
> 73 de James K2QI

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[Dick Dickinson]

Is there documentation available on the 'extended low frequency response'
found in the board exchange, separate from or including the LPF mod?
Charts, measurements, etc...

73,
Dick - KA5KKT

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

>Do note that the LPF mod does NOT give you the extended low frequency  
>response on TX and RX that you would get with the board exchange.

>73
>--
>Joe KB8AP

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[AD4C2009]

Oh yes I have done all the measurements,I have the modified DSP board for wider audio and after installed and all the upgrades till 3.76, my RX audio bandwith goes from 60 to 3600Hz and my TX audio can go as low as 70Hz and as hight as to 3800Hz as well but normally I keep it from 100 to 3000 Hz.
You can see the audio graphs on qrz.com,.type my call sign and you get them there.73
 
Hector
AD4C
K3 # 2192

"For a refined ham it is compulsory to own a k3"

--- On Mon, 3/8/10, Edward Dickinson, III <[hidden email]> wrote:


From: Edward Dickinson, III <[hidden email]>
Subject: Re: [Elecraft] [K3] LPF DSP modification
To: [hidden email]
Date: Monday, March 8, 2010, 4:26 PM


Is there documentation available on the 'extended low frequency response'
found in the board exchange, separate from or including the LPF mod?
Charts, measurements, etc...

73,
Dick - KA5KKT

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

>Do note that the LPF mod does NOT give you the extended low frequency 
>response on TX and RX that you would get with the board exchange.

>73
>--
>Joe KB8AP

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[Dick Dickinson]

Hi Hector and thanks for the reply.
 
I've done the main board mods for audio output, but don't think I've seen
the ones specificly for the DSP board...other than the LPF.  Are those mods
listed on the Elecraft site?
 
Thanks pointing me towards your qrz page.
 
73,
Dick - KA5KKT
 
 
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[Grant Youngman]

On Mar 8, 2010, at 9:47 AM, K2QI wrote:
>
> Anyway, just going over the instructions and I'm curious as to how you guys
> that have done this mod have gone about cutting the two traces?  Would an
> exacto knife work?

Yep, works well.  Use a new sharp blade.  I would not recommend a belt sander, electric carving knife or Dremel tool :-)

I'm in the middle of installing the option on my DSP board now, along with playing catchup on a few other mods now that the K144XV has arrived.

Grant/NQ5T
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[Grant Youngman]

On Mar 8, 2010, at 10:05 AM, Joe Planisky wrote:

>
> Do note that the LPF mod does NOT give you the extended low frequency  
> response on TX and RX that you would get with the board exchange.  If  
> that's not important to you, then the DIY option is a good way to go.
>

???  Are you saying that Elecraft makes additional changes on the "C" board that are not part of the LPF addition?

Grant/NQ5T
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[K2QI]

Thanks to all for your replies.  I think I'll definitely pursue the DIY
method rather than wait.  I don't need the extended low frequency response;
in fact, I think the K3 in stock form does pretty well in that area - at
least with my particular unit.  I am disturbed from the high frequency
artifacts that manifest themselves from time to time however, and that's
where I think the LPF would be most beneficial.

73 de James K2QI
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[Joe Subich, W4TV-4]

> ???  Are you saying that Elecraft makes additional changes on
> the "C" board that are not part of the LPF addition?

Yes, you can find them by comparing the January 2010 schematics
to previous schematics.  The changes are similar to the W9AC mods
but they involve scaling resistors instead of capacitors.

The changes are not necessary if: 1) you use high impedance
headpones and 2) you don't care to create multiple "false
carriers" in ESSB operation (extended low frequency transmit).

The "low frequency response" modifications are strictly for
extended response below 100 Hz.

73,

   ... Joe, W4TV
   

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Grant Youngman
> Sent: Monday, March 08, 2010 12:05 PM
> To: Elecraft Reflector
> Subject: Re: [Elecraft] [K3] LPF DSP modification
>
>
>
> On Mar 8, 2010, at 10:05 AM, Joe Planisky wrote:
>
> >
> > Do note that the LPF mod does NOT give you the extended low
> frequency
> > response on TX and RX that you would get with the board
> exchange.  If  
> > that's not important to you, then the DIY option is a good
> way to go.
> >
>
> ???  Are you saying that Elecraft makes additional changes on
> the "C" board that are not part of the LPF addition?
>
> Grant/NQ5T
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

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[Philippe Trottet]

James,
I've received the lpf module within 2 weeks following the order and installed it two days ago.
Very simple to install. Use a thin cutter for airplane mock-up, soldering iron with fine tip. Do not forget the wrist strap w/1Megohm resitor.
Just follow step by step,10 pages, the installation procedure.

Can feel the difference in my Sony MDR 7505 headsets, the listening is less aggressive to the ears on cw & ssb weak signals in a noisy environment like mine, industrial area, making some improvment on weak signals.

Thanks to Elecraft for that useful add-up.
73's
Philippe A65BI
K3#3616

>>> K2QI <[hidden email]> 08-03-2010 19:47 >>>
Just saw that Elecraft is now offering a DIY kit to upgrade your current DSP
board with the LPF module.  This is a good option as the current exchange
program is taking waaay too long.  I was on the list to receive an upgraded
board since early December and still nothing.  I finally decided to take
myself off the list, and I think I'll pursue the DIY option instead.

Anyway, just going over the instructions and I'm curious as to how you guys
that have done this mod have gone about cutting the two traces?  Would an
exacto knife work?

73 de James K2QI

P.S.  Hope you all had fun during this weekend's ARRL DX contest... I
participated just for fun and was able to bag a few countries I didn't have
before.
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[Grant Youngman]

Which rev level boards are you all talking about.  The "B" board (pre-LF mods), the "C" board which supposedly has these LF mods installed, or the "D" board which was advertised as being the same as the "C"-level board with the factory addition of the LPF.

I thought the only difference between the "C" board and the "D" board was the LPF module.

None of this means anything without specifying the rev levels.

Grant/NQ5T


On Mar 8, 2010, at 12:06 PM, Merv Schweigert wrote:

> Yep,  they have changed a number of components on the board itself,  
> resistors and caps,  mostly for better low freq response,  
> Someplace I had seen there were something like 14 changes in parts.
> But I may be mistaken on that number count.
> 73 Merv KH7C
>>
>> ???  Are you saying that Elecraft makes additional changes on the "C" board that are not part of the LPF addition?
>>
>> Grant/NQ5T
>> ______________________________________________________________
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>>  
>

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[Grant Youngman]

Hector,

My apologies for being redundant   ... Same question to you, Joe and Merv ..

You have to specify which rev level boards you're talking about.  The "B" rev board was the board before any changes were made.  The "C" board has the LF response improvements.  The "D" board is a "C" board with the LPF.

If we're not specific, none of the comments make sense.

Let me be specific in my question.  If I add the LPF daughter board to the "C" level DSP board, are there ADDITIONAL changes that were made to get to the factory "D" level board or not, beyond what is already in the "C" board?  Maybe Elecraft would chime in on this just for clarification.

Thanks ... Grant/NQ5T


On Mar 8, 2010, at 12:48 PM, Hector Padron wrote:

> Grant the extra low pass filter board is what it is,to cut down the "highs" but the low end mod is something totally different,its a change of components to lower the RX and TX roll off down to 50Hz.Some users say they don't like it and leave their radios the way it came from factory,.some others like me like to hear the lows and we did the swap of the whole board.
>  

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[Joe Planisky]

Elecraft explains it pretty clearly at

http://www.elecraft.com/K3/mods/dsp_rev_c_information.htm

The original post was from someone who was going to do the board swap,  
but decided to go with the user installed LPF option instead.  I  
pointed out (or intended to) that the K3DSPUPGD (the board swap)  
included the improved low frequency response modifications, whereas  
the K3DSPLPF (the user installed LPF board) did not.

I guess what I should have said was that installing the K3DSPLPF  
option did not change the low frequency response.

My (intended) point was that if they didn't already have the improved  
low frequency response and wanted it, they should stick with the board  
swap.  If they didn't care about the improved low frequency response  
or already had it, then installing the LPF board themselves was a  
reasonable alternative to waiting for the board swap.

I did not intend to imply (and I have no knowledge of) any further low  
frequency response circuit changes since rev C.   I do not work for  
Elecraft.  I have no inside information.  All I know about their  
products comes from information that's publicly available on their web  
site.

73
--
Joe KB8AP

On Mar 8, 2010, at 11:56 AM, Grant Youngman wrote:

> Let me be specific in my question.  If I add the LPF daughter board  
> to the "C" level DSP board, are there ADDITIONAL changes that were  
> made to get to the factory "D" level board or not, beyond what is  
> already in the "C" board?  Maybe Elecraft would chime in on this  
> just for clarification.
>
> Thanks ... Grant/NQ5T

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[Grant Youngman]

My only point here was that "it depends"  --- on what rev level DSP board is already in the radio.  If you swap a "C" level board for a "D" level board you get the LPF.  If you swap a "B" level board you get both the LPF and improved LF response.  So it's key to know what rev level is in the radio to know what the impact of DIY'ing  the LPF or a swap will be.

Grant/NQ5T


On Mar 8, 2010, at 2:59 PM, Joe Planisky wrote:

> Elecraft explains it pretty clearly at
>
> http://www.elecraft.com/K3/mods/dsp_rev_c_information.htm
>
> The original post was from someone who was going to do the board swap, but decided to go with the user installed LPF option instead.  I pointed out (or intended to) that the K3DSPUPGD (the board swap) included the improved low frequency response modifications, whereas the K3DSPLPF (the user installed LPF board) did not.
>
> I guess what I should have said was that installing the K3DSPLPF option did not change the low frequency response.
>

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[Philippe Trottet]

Forget: DSP Board "C"

James,
I've received the lpf module within 2 weeks following the order and installed it two days ago.
Very simple to install. Use a thin cutter for airplane mock-up, soldering iron with fine tip. Do not forget the wrist strap w/1Megohm resitor.
Just follow step by step,10 pages, the installation procedure.

Can feel the difference in my Sony MDR 7505 headsets, the listening is less aggressive to the ears on cw & ssb weak signals in a noisy environment like mine, industrial area, making some improvment on weak signals.

Thanks to Elecraft for that useful add-up.
73's
Philippe A65BI
K3#3616

>>> K2QI <[hidden email]> 08-03-2010 19:47 >>>
Just saw that Elecraft is now offering a DIY kit to upgrade your current DSP
board with the LPF module.  This is a good option as the current exchange
program is taking waaay too long.  I was on the list to receive an upgraded
board since early December and still nothing.  I finally decided to take
myself off the list, and I think I'll pursue the DIY option instead.

Anyway, just going over the instructions and I'm curious as to how you guys
that have done this mod have gone about cutting the two traces?  Would an
exacto knife work?

73 de James K2QI

P.S.  Hope you all had fun during this weekend's ARRL DX contest... I
participated just for fun and was able to bag a few countries I didn't have
before.
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[Dick Dickinson]

Per Elecraft's info, I have a pre-Rev. C DSP board (#1030).  Were there
pre-Rev. B DSP boards issued from Elecraft?  Other than schematics, is there
documentation available of the changes from Rev. B DSP to Rev. C DSP?

73,
Dick - KA5KKT
----------------------------------------------------------------------------
----------------------

Yes, you can find them by comparing the January 2010 schematics
to previous schematics.  The changes are similar to the W9AC mods
but they involve scaling resistors instead of capacitors.

73,

   ... Joe, W4TV

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