Thanks for saving me the effort of doing the testing on ceramic resonators! I
see Rapid also stock these, and the 11.0592 xtals too.
I've got my NoV application ready to post tonight and I retire on Monday, so
hopefully I can turn all this blathering into results within a couple of weeks!
[email protected] wrote:
> Hi Alan, Alan and LF.
> I've done a few tests with trying to "pull" crystals and resonators up into
> the 501-504 kHz band. I used a single NPN transistor in a Colpits
> configuration with a 3 - 30pf trimmer capacitor in series with the crystal.
> Firstly, I tried a few 1.000 and 2.000 MHz HC6u crystals, available from RS
> Components. These would only move a few tens of Hz maximum, before they
> Secondly, I tried ten 500kHz resonators, type Murata 500 CSB. These are
> little yellow plastic cuboids approx 10 x 8 x 4 mm with two legs at the
> bottom. These all came out low, typically in the 498-499 kHz range, and
> couldn't be pulled much higher before they died.
> Thirdly, I tried some 1 MHz resonators, type Murata 1000J. These are even
> smaller blue plastic cuboids approx 7 x 5 x 2mm also with two legs on the
> bottom. These were much more amenable to "pulling", and would tune from 989
> to 1011 kHz quite happily (494.5 to 505.5 kHz) The frequency stability seems
> quite good, and a hot soldering iron on one of the legs moved the frequency
> about 200 Hz, coming back on frequency as it cooled down. You would need to
> be careful using one of these, however, as you could easily slip out of band
> if you moved the trimmer too far.
> So one of these 1MHz resonators would seem to be a good source, once divided
> by two. You could leave the oscillator running continously for maximum
> stability, and key the divider. I might even have a circuit of a divider
> using a double triode if anyone wanted to stay with the retro "Valve theme"!
> Otherwise a 74LS74 or a CD 4013 will do the trick nicely.
> BTW, RS Components and Farnell sell a 11.0592 MHz crystal, costing the
> princely sum of 19 pence, which when divided by 22 will give 502.69 MHz.
> (74LS161 followed by 74LS74...no problemo...)
> 73, Dave G3WCB IO91RM
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Alan Melia
> Sent: 23 April 2007 23:36
> To: [email protected]
> Subject: Re: LF: 500 EASY START
> Hi Alan, there is not a lot of "accumulated wisdom" on 500kHz yet but most
> of the 136khz experience seems to work. The best tutorial for aerials at LF
> is the pages by Rik Srobbe ON7YD. You will find a lot else there as well.
> http://www.qsl.net/on7yd/ and click on "The 136kHz Amateur Band" in the
> left-hand bar.
> Low frequency crystals are almost unknown these days. It is so easy to
> divide down. Two techniques have been used straight division like Mal
> suggests or mixing crystals in the 5 to 6 meg range...pulling one up and the
> other down with a 2 gang variable cap. as Dave Sargent recently described.
> Have you though of trying at 50p ceramic resonator !! 500kHz is a stadard
> frequency for these and they are fairly "bendable" so may come up into the
> band. I think GW3EUP uses one.
> You will find a spreadsheet on my web site (beside a lot of other junk)
> which attemmpts to simplify the ERP calculation.
> It is an EXCEL sheet and should download OK.
> I hope that helps ...welcome to LF and remember LF=Lotsa Fun !!
> Cheers de Alan G3NYK
> ----- Original Message -----
> From: Alan Ibbetson <[email protected]>
> To: <[email protected]>
> Sent: 23 April 2007 23:03
> Subject: Re: LF: 500 EASY START
> > Hello everyone, Alan G3XAQ here. I just joined this mailing list. I'm
> > preparing my application for a 501KHz NoV, so Mal's note on an easy
> > start is very timely.