[Elecraft] K3 Roofing Filter Gain Setup

[Brian Alsop]

On 5/29/2011 13:43, drewko wrote:
> If I use a 50uv signal generator to set the filter gains for equal
> readings on my K3's AFV meter I arrive at the following compensations:
>
> 2.70 KHz = 0db
> 500 Hz = 4 db
> 250 Hz = 8 db
>
> This is way more aggressive than the suggested amounts but these
> figures do sound equalized to my ears for real signal conditions. The
> factory settings are noticeably weak. Maybe my particular filters are
> just not up to par.
>
> 73,
> Drew
> AF2Z
>
>
> On Sat, 28 May 2011 14:18:45 -0700, you wrote:
>
>> There are recommendations in the K3 Owner's manual (see "Crystal Filter
>> Setup", indexed, on page 46) :
>>
>> Use VFO A to set the gain in dB. In general, you'll want to add 1-2 dB for
>> 400-500 Hz filters, and 3-4 dB for 200-250 Hz filters.
>>
>> and there is a table (with essentially the same guidance) in K3 Utility Help
>> for the Filter Configuration page. I've lost the table formatting in
>> cut/paste from Help, but here's the information:
>>
>> Narrow crystal filters tend to have more passband loss than wide filters.
>> You can compensate for this effect by specifying an amount of added gain to
>> use for each filter in receive mode. Enter the desired gain "boost", in
>> decibels, for each filter. You may specify a value between 0 and 8 dB.
>>
>> Elecraft recommends using the initial loss compensation values below. You
>> may wish to further adjust the values for your particular filters.
>>
>> Part Number Bandwidth Gain
>>
>> KFL3A-200 0.20 kHz 3-4 dB
>> KFL3A-250 0.25 kHz 3-4 dB
>> KFL3A-400 0.40 kHz 1-2 dB
>> KFL3A-500 0.50 kHz 1-2 dB
>> KFL3A-1.0K 1.00 kHz 0 dB
>> KFL3A-1.8K 1.80 kHz 0 dB
>> KFL3A-2.1K 2.10 kHz 0 dB
>> KFL3A-2.7K 2.70 kHz 0 dB
>> KFL3A-2.8K 2.80 kHz 0 dB
>> KFL3A-6K 6.00 kHz 0 dB
>> KFL3B-FM 13.00 kHz 0 dB
>>
>> 73 de Dick, K6KR
>>
>>
>
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