[Elecraft] K3 Sub-receiver use

Mon May 31 13:57:48 EDT 2010

Hi Guy,

All OK !

Effectively, i don't envisage to "look" for 50MHz activity
on the P3 during transmitting on lower bands.

I will look at the K3 schematics how are switched
antennas, KAT3,  KRX3, etc.
I'm not 100% ok with all these connections for the moment...
and how TX/RX switching is done...

I've the KAT3 installed and i'm using ANT2 input
for 50MHz antenna.

I think that P3 "monitoring" can be useful also
for K144XV or external transverter users on higher bands
where some "nice" apertures can  appears.

Thank you to you, Guy, and all OM for very good informations
and help in my choice!

73 QRO,
Rudolf, HB9ARI

Guy Olinger K2AV wrote:
> Yeah,
>
> The rub is getting Wayne to add an option that will look at the subRX
> for the P3 interface functions.  Think you might get what you're
> asking for.
>
> Others are asking for that to be switchable back and forth between the
> two *dynamically*.  This involves both IF's and allows for signals in
> the IF of one RX to be heard in the other.  This would a switch with
> 100 dB isolation.  It would be an expensive option, plus some
> significant new code.  Don't think this complexity is commercially
> feasibility.
>
> BTW, none of this would allow the subRX to listen while transmitting.
> They are all in the same box and running full duplex will require
> circuits with isolations in the 140, 150 dB range to work right.
> Talking about military applications, and very expensive radios for
> that kind of thing.
>
> 73, Guy.
>
> On Mon, May 31, 2010 at 3:04 AM, hb9ari <hb9ari at bluewin.ch> wrote:
>   
>> Hi Guy,
>>
>> It's that way i was thinking to use the P3!
>> -1- ALWAYS on the sub-receiver output.
>> -2- ALWAYS on a separated antenna.
>>
>> My idea was to externally switch the 6m
>> (or internally if possible?) antenna from
>> K3 sub-rcvr to main RF when some activity
>> was "detected" on th P3. When "working"
>> on 6m, no necessity, (always speaking
>> for me..) to "monitor" a 10 to 20m band!
>>
>> In my case, as i'm very space limited,
>> no room for a 2nd 10 to 20m separated
>> antenna for diversity...
>> But a separated 6m antenna is feasible.
>> (for the moment, i use only a vertical for
>> 6m, no DX, but not too bads QSO)
>>
>>
>> 73,
>>
>> Rudolf, HB9ARI
>>
>> Guy Olinger K2AV wrote:
>>     
>>> The trick involved in that switch is a very high isolation between the
>>> two IF's (RXA and RXB) currently very nicely highly isolated.  If that
>>> is degraded, then one starts hearing in one receiver the contents of
>>> the other. Not at all a trivial modification, as high isolation
>>> switches are not cheap.  So I suspect dynamically selecting display on
>>> one RX or the other has a big price tag to it. And perhaps has an
>>> internal space price to it.
>>>
>>> I would think, however, that when installing a sub-RX, that perhaps it
>>> could be cabled and the K3 options set to use the sub-RX on the P3 all
>>> the time, WITHOUT opening the pandora's box of high-isolation
>>> switching of RX IF's. This would be in the same vein as choosing the
>>> RX paths when installing the sub-RX to start with.  Without the time
>>> to think that through carefully, I'd currently chose that were it
>>> available.
>>>
>>> 73, Guy.
>>>
>>> On Wed, May 26, 2010 at 12:29 PM, Radio Amateur N5GE <n5ge at n5ge.com> wrote:
>>>
>>>       
>>>> On Tue, 25 May 2010 21:25:15 -0700, Alan Bloom <alan at elecraft.com>
>>>> wrote:
>>>>
>>>> Ouch!
>>>>
>>>> Does this mean that the P3 will not display the frequency of or the
>>>> signals seen by the KRX3?
>>>>
>>>> If that is true, it is a show stopper for me.
>>>>
>>>> TOM, N5GE BT 73 ES GUD LUK
>>>> AR DE N5GE SK
>>>>
>>>> http://www.n5ge.com
>>>>
>>>>
>>>>         
>>>>> Yes, the P3 assumes it is connected to the main receiver's IF output, so
>>>>> if it is actually connected to the sub-RX it would still work but would
>>>>> not display the correct frequencies and levels.  If this becomes popular
>>>>> enough maybe we should think about adding sub-RX support to P3 firmware.
>>>>>
>>>>> Alan N1AL
>>>>>
>>>>>
>>>>>           
>>>> [snip]
>>>>
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