Hi Brendon,
In a way you are right, but consider this: the per-band nulling procedure is to
compensate for amplitude and phase variations introduced in the LO and quad
mixer which can be different from band to band. However, when you put a roofing
filter in the signalling path, it will introduce a further amplitude and phase
imbalance (which as you say will be the same for all bands). The per-band
nulling parameters you set up before adding the roofing filter will all need to
be adjusted to take the impact of the roofing filter into account. This is why
you should repeat the whole nulling calibration for each band when you add a
roofing filter. Does this make any sense?
73, Matt VK2RQ
_____________________________
From: Brendon Whateley <[email protected]>
Sent: Saturday, October 8, 2016 3:00 am
Subject: Re: [Elecraft] Soon to be an Elecraft(er)!
To: Matt Maguire <[email protected]>
Cc: Elecraft Reflector Reflector <[email protected]>, Ray Sills
<[email protected]>
Given my understanding of the roofing filter design in the KX3, I don't think
there is any per-band adjustments to make. IIRC, the filter is an analog
low-pass filter that operates after the direct down-conversion.
If I'm wrong, then please set me straight. Especially because I'm considering
adding the filter to my KX3.
- Brendon
On Thu, Oct 6, 2016 at 11:35 PM, Matt Maguire <[email protected]> wrote:
Does the factory do a full per-band calibration, or do they just calibrate on
20m and extrapolate? If the latter I'd suggest to do the full per-band
calibration yourself even for a factory-fitted roofing filter, as it does make
a difference (obviously back up your config first so you can restore to factory
settings/calibration if needed)
73, Matt VK2RQ
On Fri, Oct 7, 2016 at 5:38 AM +1100, "Ray Sills" <[email protected]> wrote:
Also, IF you order the roofing filter for the KX3…. even with a kit purchase….
the factory will calibrate it for you, so all you need do is install the little
board. They have a test jig, so that the filter will be tested with YOUR
particular main board. Best of both worlds… save some money, and get free
factory calibration.
73 de Ray
K2ULR
KX3 #211
> On Oct 6, 2016, at 12:00 PM, Walter Underwood wrote:
>
> The roofing filters require some calibration. If they are factory-installed,
> Elecraft does that for you. All the other options are exactly the same
> whether factory-installed or user-installed.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
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