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Re: LF: [ 500] EASY START - ceramic resonators et al

To: <[email protected]>
Subject: Re: LF: [ 500] EASY START - ceramic resonators et al
From: "Dave Brown" <[email protected]>
Date: Thu, 26 Apr 2007 01:42:11 +1200
Delivered-to: [email protected]
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
So just how stable are the resulting outputs using these things?
Anyone looked at that yet? Its a given that you will need very good to
excellent frequency stability once things go beyond the aural CW
stage.(And I'm not saying that's good or bad-just that it's bound to
happen!)

A reminder that some rigs will likely work 'as is' on 500 kHz- I have
only tested the Yaesu FT757GX II but  Yaesu rigs with similar pa
design are likely to also work OK.  Only proviso is to keep the output
down to 50 watts or so-try for any more out and it shuts
down-presumably in self protetction mode. From memory rx sensitivity
is in spec or very close to-would have to check again to verify.
73
Dave, ZL3FJ (a 500 kHz waiter!)

----- Original Message ----- From: <[email protected]>
To: <[email protected]>
Sent: Thursday, April 26, 2007 12:34 AM
Subject: Re: LF: [ 500] EASY START - ceramic resonators et al


Dave,

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!
73,

Alan

[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
stopped.

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.
http://www.btinternet.com/~alan.melia/programs.htm
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.










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