I installed this last night in K3#51. I'm running uC 2.67, which
features the AGC-OFF hearing protection.
I'm trying to decide what LINE OUT and AGC setting to use for digital
modes with.
If AGC is disabled, line out values 0, 1, 2, 3, and 4 produce strong
differences. After that I see almost no change in output.
If AGC is enabled, even moderate signals produce enough AGC action (even
if AGC threshold is pegged) so that I need LINE OUT of 30 or so to get
enough output.
For now I get the best results in data modes with AGC OFF and a LINE OUT
level of 5.
Leigh/WA5ZNU
This information and a mod manual are now on our K3 Enhancements and
Applications note page. See:
http://www.elecraft.com/K3/k3_app_notes.htm
I apologize for the delay getting this posted! It should have been up
earlier.
>From that page:
Line-Out KIO3 R19/R20 Change:
About Oct 7, 2008
About S/N 1900
Speaker Amp RFC47 Change:
About Sept 25, 2008
About S/N 1830
(Dates and serial numbers are approximate and may vary slightly.)
73, Eric WA6HHQ
------
N6WG wrote:
> I would also like to know that please.
> 73, Igor UA9CDC
>
>> Wayne
>> Can you tell us the serial number at which
>> these changes were incorporated?
>> We need to know who needs to order them
>> and who does not.
>> Thanks and 73
>> Bob N6WG
>>
>> ----- Original Message ----- From: "wayne burdick" <[EMAIL PROTECTED]>
>> To: "Elecraft Reflector" <[email protected]>
>> Sent: Thursday, November 13, 2008 10:40 AM
>> Subject: [Elecraft] K3 AF Upgrade Kit (for speaker amplifier and LINE
>> OUTs)
>>
>>
>>> With minor circuit changes, both the K3's speaker amplifier and line
>>> outputs can provide lower IMD (intermodulation distortion) at higher
>>> signal levels. We've been testing these changes for a couple of
>>> months, and have already phased them into production.
>>>
>>> These changes can easily be made to existing K3s. A kit of parts is
>>> available (K3AFMDKT). All parts are leaded (not surface mount), and
>>> full instructions are provided. See:
>>>
>>> http://www.elecraft.com/order_form_parts.htm#K3%20Parts
>>>
>>> Details
>>> -------
>>>
>>> SPEAKER AMP: The mod kit includes a very low-resistance RF choke
>>> for use at RFC47 on the RF board. This improves speaker amplifier
>>> IMD by as much as 25 dB at moderate to high AF GAIN settings by
>>> reducing the voltage drop across RFC47 during signal peaks.
>>>
>>> LINE OUT: The kit also includes smaller resistor values for R19 and
>>> R20 on the KIO3 module. At present R19 and R20 are about 600 ohms,
>>> while the replacements drop the resistance to around 50 ohms. The
>>> smaller resistors increase the available voltage swing at the output
>>> of the LINE OUT transformers, which improves IMD at higher signal
>>> levels.
>>>
>>> These two changes are independent. For example, if you never use
>>> LINE OUTs, you might want to do only the speaker amp modification.
>>>
>>> 73,
>>> Wayne
>>> N6KR
wayne burdick wrote:
With minor circuit changes, both the K3's speaker amplifier and line
outputs can provide lower IMD (intermodulation distortion) at higher
signal levels. We've been testing these changes for a couple of
months, and have already phased them into production.
These changes can easily be made to existing K3s. A kit of parts is
available (K3AFMDKT). All parts are leaded (not surface mount), and
full instructions are provided. See:
http://www.elecraft.com/order_form_parts.htm#K3%20Parts
Details
-------
SPEAKER AMP: The mod kit includes a very low-resistance RF choke for
use at RFC47 on the RF board. This improves speaker amplifier IMD by
as much as 25 dB at moderate to high AF GAIN settings by reducing the
voltage drop across RFC47 during signal peaks.
LINE OUT: The kit also includes smaller resistor values for R19 and
R20 on the KIO3 module. At present R19 and R20 are about 600 ohms,
while the replacements drop the resistance to around 50 ohms. The
smaller resistors increase the available voltage swing at the output
of the LINE OUT transformers, which improves IMD at higher signal
levels.
These two changes are independent. For example, if you never use LINE
OUTs, you might want to do only the speaker amp modification.
73,
Wayne
N6KR
---
http://www.elecraft.com
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