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Re: choice of IF frequencies

>From: Estes Wayne-W10191 <Wayne_Estes-W10191@email.mot.com>
>Ed Cole wrote:
>I just pre-ordered* my 1269 Tx conv. & 10451 Rx conv. from Steve [DEM]
this morning and the schedule sounds about right.  They are holding on
production to be sure of which AO-40 modes checkout good, and for some
verification of link requirements by actual observation {i.e. if they make
a bunch of 10w convertors and you need 20w...they are stuck with unwanted
>Wayne Estes replies:
>I notice that DEM's 1269 transmit converter and the 2400 MHz MHz RX
converter both have 144 MHz IF's.  Why?
>It seems obvious to me that AO40 transmit and receive converters should
use DIFFERENT IF's.  The logical choice for the transmit IF is 435 MHz.
Then the 2400 MHz and 1269 MHz converters would be "plug and play" with
EVERY commercially made satellite transceiver, including models that don't
have HF capability.
>This seems even more compelling if AO-40's 435 MHz transmitter really
turns out to be dead.  435 MHz would be an "uplink only" band, perfect as
the IF for ALL AO-40 transmit converters.
>Has anybody asked DEM why they don't plan to offer the 1269 MHz transmit
converter with a 430 MHz IF?  Is something wrong with my logic?


No, you are addressing a real problem for setting up a station that can
work many different modes.  If you look futher it becomes even more complex:
Modes I think will be implemented:

For instance your L is V:L then K should be U:K, but now you can't operate
mode UK.
For instance your C is V:L:C, and V:X, but now you cannot operate mode CX
For most, the problem will be incompatibilty between US and LS!  

I suggest you talk with Steve at Downeast.  I believe there may be options
on special order.  You can see why they are waiting to see what mode
combinations are operational and chosen as standards.

No easy anwers, here!


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