I'm almost positive that it's a Celwave, not a Sinclair, but I don't
recognize that exact part number. Their tunable low-pass filters (actually
second harmonic notch filters) had part numbers like AF150-T which was for
highband VHF (the 150 being the nominal center of the passbasnd frequency,
i.e. 150 MHz, with the reject notch being 2X that frequency).
If you sweep it, it will be obvious how it works/tunes. You'll basically
see a notch that is tunable with the trimmer cap. It's normally tuned to
notch the transmitter's second harmonic.
--- Jeff WN3A
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Doug
> Sent: Sunday, March 22, 2009 3:54 PM
> To: [email protected]
> Subject: [Repeater-Builder] RE: AF2140 filter
>
> I have come across this filter in my junk box and am unable
> to find much
> information on it. I think it is a Sinclair unit, but does
> not appear to
> be listed in the Sinclair Catalog. I am sure it is a vhf unit
> but am not
> sure of the tuning procedures. It follows a Isolator. Is it a
> LP filter
> or a 2nd harmonic filter?? It only has one tuning control
> which is offset
> from the centre of the small block and appears to be a
> capacitor similar
> to those used in Sinclair's notch cavities. Lots of listings
> on ebay for
> them, but no tuning instructions or descriptions otherwise.
> Since I have
> it, I thought I might as well use it...
>
> How do I tune it??
>
> Thanks
>
> Doug
>
>
>
>
>
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>
>
