Sub RX Filters choice

[mm0gpz]

Hi.

My K3 has a standard 2.7 Khz ssb filter, a narrow 2.1 Khz ssb filter and a
400 hz cw filter.


I am planning to purchase the sub RX KRX3 and would like some filter advice
please. I am much more interested in CW.

Do I have to match up all these filters on the Sub RX for diversity? I know
the 2.7 Khz is standard but for diversity I seem to remember reading the
same filters should be in place? I also seem to recall that the filters are
not cascaded so in essence, only one filter is in line at a time. So if I
purchase only the 400 hz filter for the sub RX, it diversity reception will
work fine as long as the 400 hz filter is selected for CW or SSB will be
fine between > 2100 and 2700?

What would happen if I engaged the 2.1 SSB filter in main RX and I don't
have same filter in Sub RX.

Thanks for your time.


Gordon
MM0GPZ
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[N0AZZ]

Gordon

I faced the same decision as you just a couple of weeks ago but note I'm not
a big CW op by any means so my filter choices reflect that. In my main I
have a 6Khz for AM, 2.8, 2.1,.400. 250Hz I do Digital also all are 8 pole
filters. First be sure that you don't want any more filters in the main
receiver as it's much more work to remove the sub-receiver to add filter to
the main later.

I decided for the sub to use 2 filters and they would cover everything with
the DSP filtering they were the 2.8 and the 400 8 pole filters. So far it
has worked out extremely well and I would not change anything nor add any
other. filters for my operating needs.

I do have 1 regret that when I ordered this K3 I had 1 already. I ordered it
fully loaded all options except one the sub receiver that I should have done
first off instead of waiting.

73,
Fred/N0AZZ

 

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of mm0gpz
Sent: Tuesday, December 18, 2012 5:28 AM
To: [hidden email]
Subject: [Elecraft] Sub RX Filters choice

Hi.

My K3 has a standard 2.7 Khz ssb filter, a narrow 2.1 Khz ssb filter and a
400 hz cw filter.


I am planning to purchase the sub RX KRX3 and would like some filter advice
please. I am much more interested in CW.

Do I have to match up all these filters on the Sub RX for diversity? I know
the 2.7 Khz is standard but for diversity I seem to remember reading the
same filters should be in place? I also seem to recall that the filters are
not cascaded so in essence, only one filter is in line at a time. So if I
purchase only the 400 hz filter for the sub RX, it diversity reception will
work fine as long as the 400 hz filter is selected for CW or SSB will be
fine between > 2100 and 2700?

What would happen if I engaged the 2.1 SSB filter in main RX and I don't
have same filter in Sub RX.

Thanks for your time.


Gordon
MM0GPZ
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[Don Wilhelm-4]

Gordon,

I am going to give you a slightly different answer than I have seen
posted on the reflector.

If diversity mode is your main consideration, then ideally, you need to
have matched filters
The 5 pole filters  can be matched at extra cost from Elecraft, but the
9 pole Inrad filters supposedly have zero offset and do not have to be
matched.

The matching problem becomes less important at wider filter bandwidths,
so since you have the 2.7 kHz filter in the main already, you can get
another 2.7 for the subRX and average the offsets.  It is not the ideal,
but it will work fine for diversity reception.

73,
Don W3FPR

On 12/18/2012 6:28 AM, mm0gpz wrote:

> Hi.
>
> My K3 has a standard 2.7 Khz ssb filter, a narrow 2.1 Khz ssb filter and a
> 400 hz cw filter.
>
>
> I am planning to purchase the sub RX KRX3 and would like some filter advice
> please. I am much more interested in CW.
>
> Do I have to match up all these filters on the Sub RX for diversity? I know
> the 2.7 Khz is standard but for diversity I seem to remember reading the
> same filters should be in place? I also seem to recall that the filters are
> not cascaded so in essence, only one filter is in line at a time. So if I
> purchase only the 400 hz filter for the sub RX, it diversity reception will
> work fine as long as the 400 hz filter is selected for CW or SSB will be
> fine between > 2100 and 2700?
>
> What would happen if I engaged the 2.1 SSB filter in main RX and I don't
> have same filter in Sub RX.
>
> Thanks for your time.
>
>

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