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<blockquote data-quote="Llew" data-source="post: 629996" data-attributes="member: 175007"><p>Hi Dave</p><p></p><p>I managed to find the preamp I made after rooting at the back of my junk cupboard.</p><p></p><p>It's a little worse for wear now, having removed it from its box a while ago, breaking the output capacitor in the process. I used striplines etched on a glass fibre board. </p><p></p><p>I haven't got the original circuit I'm afraid, all I know is that the transistor was a NE21936 bipolar UHF type, the Zener biassing diode at the top 8.2V. The ferrite beads had resisistors inside supplying the voltage to the transistor. Power supply was (I think) 10V.</p><p></p><p>I've no idea what the gain was of the preamp, all I know is that it was adequate, as I used to be in line of sight of the top of the repeater's mast before apartment blocks obscured the view.</p><p></p><p>Not really enough info I'm afraid for you to build it, although if needed, I can check the value of the other components if you want.</p><p></p><p>My antenna was just a lash-up using heavy-guage copper wire for the elements, all pushed through a hard plastic rod for the boom <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite9" alt=":eek:" title="Eek! :eek:" loading="lazy" data-shortname=":eek:" /></p><p></p><p>Llew</p></blockquote><p></p>
[QUOTE="Llew, post: 629996, member: 175007"] Hi Dave I managed to find the preamp I made after rooting at the back of my junk cupboard. It's a little worse for wear now, having removed it from its box a while ago, breaking the output capacitor in the process. I used striplines etched on a glass fibre board. I haven't got the original circuit I'm afraid, all I know is that the transistor was a NE21936 bipolar UHF type, the Zener biassing diode at the top 8.2V. The ferrite beads had resisistors inside supplying the voltage to the transistor. Power supply was (I think) 10V. I've no idea what the gain was of the preamp, all I know is that it was adequate, as I used to be in line of sight of the top of the repeater's mast before apartment blocks obscured the view. Not really enough info I'm afraid for you to build it, although if needed, I can check the value of the other components if you want. My antenna was just a lash-up using heavy-guage copper wire for the elements, all pushed through a hard plastic rod for the boom :eek: Llew [/QUOTE]
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