[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: choice of IF frequencies



Hi John,
435 is not necessarily bad for a 1269 up converter.. if you take 436 and
use helixfilters in the converter, there isn't any problem.. and you
can't fill your 435 rx with the 3rd harmoinc of the 144 tx if used that
way... I am going to use it with 436->1269 and 2400->144 (up converter
available from www.db6nt.com)

73s Achim, DH2VA

"John Stephensen, KD6OZH" wrote:
> 
> 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.
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> 
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home