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Message-ID: <6B19E6A235CD4B6387D6C9F1DEDB7025@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <1f0624b91001131347i18ff85bbxb5977cdcb3c438f5@mail.gmail.com> <20100113220536.23ff9c6e@opc1> <20100113232415.j3jn4brkyqs4gg0s@webmail6.kuleuven.be> <CE0B95E8C8B24987B4FD88B20717C3B1@JimPC> <1f0624b91001140306k7eff5b4cn9ae73cb5cc6a37fc@mail.gmail.com> <9afca2641001140408o9e58f8g36272480eb115958@mail.gmail.com> <fc7eccec1001140432g1cc416f8l29d1a7b77ed1f7e0@mail.gmail.com> <9afca2641001140546v61772ef5mbb0fa9510db5eba@mail.gmail.com> <fc7eccec1001141222o2a362342pdfb91d861652d940@mail.gmail.com>
In-Reply-To: <fc7eccec1001141222o2a362342pdfb91d861652d940@mail.gmail.com>
Date: Thu, 14 Jan 2010 21:04:01 -0000
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Subject: Re: LF: 500khz WSPR drift
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Dear Andy, Roger, LF Group,

In my transverter design, I have added a "ref out" socket to the IC718 
driving transceiver to make the 32MHz reference oscillator available 
externally. This is divided to 4MHz for use as the LO in the transverter 
mixer. The overall frequency stability is thus that of the reference in the 
IC718, which has the TCXO option, so frequency is quite accurate, within 
about 0.1Hz at 500k last time I checked, and drift during operation rather 
less than that.

BTW, I also have an FT-817 - I don't think they have done it on the cheap... 
the 22.625MHz is the actual frequency reference, driving LO and BFO DDSs via 
various multipliers and also providing the 2nd LO signal, but I think the 
22.7785 is a VCXO which is modulated by the TX audio and then tripled to 
obtain NBFM at the 1st IF frequency.

Cheers, Jim Moritz
73 de M0BMU


----- Original Message ----- 
From: "Andy Talbot" <andy.g4jnt@googlemail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, January 14, 2010 8:22 PM
Subject: Re: LF: 500khz WSPR drift


> Yes, I did :-)
>
> The FT817 block diagram shows two oscillators in the chain  a master at
> 22.625 and 'another' at 22.7785 - so that idea gets knocked out
> straightaway.  They done it on the cheap :-(
>