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Re: choice of IF frequencies



I have seen 1269 to 28 MHz boxes so I know it can be done.  With the
satellite niche market I think 50 MHz would be a great IF frequency.  With
all of the IC-910 / FT- 847 / TS-2000 supporting 50 MHz out of the box it
seems like a sensible choice.  No need to run expensive feedline to the mast
mounted converter.

Just My thoughts,
Joe
ka0yos@amsat.org

----- Original Message -----
From: "John Stephensen, KD6OZH" <kd6ozh@gte.net>
To: "Estes Wayne-W10191" <Wayne_Estes-W10191@email.mot.com>;
<amsat-bb@AMSAT.Org>
Sent: Thursday, December 07, 2000 7:46 PM
Subject: Re: [amsat-bb] choice of IF frequencies


> A 435 MHz IF would be a poor choice for a transmit converter as the third
> harmonic of the IF would pass right through the printed RF bandpass
filters
> on the unit and cause interference to other services. 144 and 222 MHz are
> the only viable choices and no one makes 222 MHz transceivers anymore. So
> the existing DEM products will limit those with dual-band satellite
> transceivers to mode LU (AO-13 mode L) and mode US (AO-13 mode S).
>
> A 2400 MHz receiving converter with a 435 MHz IF would be the best way to
> enable mode LS.
>
> John
> KD6OZH
>
> ----- Original Message -----
> From: "Estes Wayne-W10191" <Wayne_Estes-W10191@email.mot.com>
> To: <amsat-bb@AMSAT.Org>
> Sent: Thursday, 07 December 2000 20:23 UTC
> Subject: [amsat-bb] choice of IF frequencies
>
>
> > 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
> inventory}.
> >
> > 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?
> >
> > Wayne Estes W9AE
> > Mundelein, IL, USA
> >
> > p.s. I just re-subscribed to AMSAT-BB.  I used to be active on AMSAT-BB
in
> the AO13 days with callsign WD5FFH.
> >
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