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Re: LF: RE: Analog oscillators

To: <[email protected]>
Subject: Re: LF: RE: Analog oscillators
From: "Alan Melia" <[email protected]>
Date: Thu, 5 Jul 2012 23:05:03 +0100
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References: <[email protected]> <7E7DFBB4D102A04DB5ADC88D66628A4A0FAB99CC@ICTS-S-MBX5.luna.kuleuven.be> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]

Hi stefam/Ha-Jo....when I did this I chose a pair of crystal that mixes to one end of the band then pulled one upwards and the other downwards simultaneously. There still is a slight drift problem but id chosed carefull the drift on the two crystals is the same so the difference cancels it out. The remaining problem is due to the tempco of the tuning components. I also used a diferential variable capacitor for the tuning. Good quality caps are just as essenial as with VFOs.

Alan
G3NYK

----- Original Message ----- From: <[email protected]>
To: <[email protected]>
Sent: Thursday, July 05, 2012 9:44 PM
Subject: Re: LF: RE: Analog oscillators


Dear Stefan,

Yes. xtal 7,02 MHz will run stable, and xtal 6,5536 MHz must be pulled
down by 12,6  kHz to 6,5410 MHz. A coil in series to the crystal and the
tuning capacitor will do this, in its simpiest form by using a molded rf
choke.

Or 7,0200 MHz is adjusted for 7,0256 MHz, then 6,5536 Mhz will deliver a
difference frequency of 472 kHz. And when 6,5536 MHz is pulled down to
5.6466 MHz, the difference will be 479 kHz.

OK?

73 Ha-Jo, DJ1ZB


"Stefan Schäfer" <[email protected]> schrieb:
Hello Ha-Jo,

Can you pull one of the xtals to cover the whole band?

73, Stefan

Am 05.07.2012 20:57, schrieb [email protected]:
> Dear all,
>
> the only parts I have bought so far for MF (still beeing engaged in
> other developments) are two crystals: 6,5536 MHz and 7,0200 MHz, to be
> mixed with each other. The mixer is another bipolar transistor, and its
> emitter current is being keyed. A final source follower after the
> low-pass filter will deliver the output to 50 ohms.
>
> The same solution I have also used on LF.
>
> 73 Ha-Jo, DJ1ZB
>
>
>







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