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Date: Thu, 25 Oct 2007 17:45:26 +0100
From: "Andy Talbot" <andy.g4jnt@googlemail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: 500 tx
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Write it up and send it in...

Andy  G4JNT
www.scrbg.org/g4jnt


On 25/10/2007, hamilton mal <g3kev.ham@virgin.net> wrote:
> Hi all
> I built a class E type TX in a couple of days, my own design layout etc an=
d
> kept it simple, but I am experienced having built equipment over the years
> from the valve era, then transistors and today mostly IC technology. The
> problem for most would be getting the components and this is where Radcom
> falls down, not a single advert even for a resistor. The trouble with the
> big suppliers like Farnell is the cost ie minimum order of =A320 each time=
 a
> component is required.
> My EASY START tx should be easy to get going for most and I would submit t=
he
> cct but I do not want to get bogged down with preparation details and find
> it would not be published in Radcom.
> My cct consists of an IC706 transmitting a couple of watts on 5 mhz / sq
> wave conv / divide by 10 / amplified by a 4426 / FET pa / matching coil/C
> cct for class E then an old TV line out transformer matching the pa to 50
> ohms / 5 pole LPF / SWR meter and away the rf goes via 50ohm coax some 50
> metres to the base of the antenna matching network / 1/4 wave inv L at abo=
ut
> 33 metres vertical and the rest horizontal.
> This is my approach and gives VFO control and good freq stability.
> Most of the components were from the junk box hence an economical build. T=
o
> date it has proved totally reliable and no smoke. Using this approach woul=
d
> be an EASYSTART for those contemplating 500.
> The PA coil is about 50 years old,  ex TU5 tuning unit ceramic former with=
 a
> tinned copper winding, just right for the job. The condensers are also ex
> equipment, high voltage.
> Is Radcom interested???
> 73 de Mal/G3KEV
>
>
>
>