Alan, thanks for all your articles. I'm into small electronic projects, and have been a pirate here in the UK... Doesn't it make you laugh when you go to great lengths to tell people how rubbish a design is, but still they want it because it 'looks neat', because its built on perfboard and it is capable of oscillation in the broadcast band? I would rather have a messy good design than a tidy crap one. My advice; google vhf oscillator and experiment: if a designer tells you themselves that a circuit is rubbish you should take the hint!

Scott R,

LOL, sure why not?

Regards,

Alan

Hey I think I heard you back then. Can I get a QSL card?

Stuart,

The VCO would not be sufficiently stable to operate on 2 metres, at least not without a PLL.

You might be able to get an old VHF commercial radio you can reprogram for 2 metres. They often come up at junk rallies for very reasonable prices.

Otherwise as it is a fixed-frequency you could build an crystal locked TX for the frequency in question. You'd need to multiply up from a lower frequency to get reasonable deviation. DSE used to sell a kit with about 1 Watt out that did just that, more output would not be too difficult to arrange.

Regards,

Alan

I too... like the look of this little VCO. How easily could it be teased into reliable service on 2m FM?

In particular, I'm looking around at a transmitter with about 5W output, to use for broadcasting the WIA National News on the VK4RBN (Mt. Glorious) Brisbane Repeater... transmitting at 146.4MHz for about 30 minutes or so. Limited income unfortunately means I cannot afford a 2m radio, and my TH-F7E handheld (sole 2m/70cm rig... the other rig is HF) will not transmit 5W for the period required.

But I pushed 40mA,12V over a 2N2219!

And, what a pretty, small,hand-held VFO! Can I take a look at the schematic?

Bert,

No, you don't!

It was a horrible beast, especially the amplifier. The output device was a 2N4427 with a clip-on heatsink. It was driven with two tuned stages which is probably why it had a tendency to take-off at the wrong frequency now and then. The oscillator was your average common-base thing, like you'd see in an FM toy microphone, feeding a simple and completely inadequate class A buffer with a tuned collector. The exciter stages were series tuned monsters with T-network matching (actually fairly good), delivering about 100 mW to that 2N4427 (probably one of the reasons I cooked a few).

Regards,

Alan

Haha, you blew the transistors once a week, almost often as me. Every 24 hours, I have to replace my transistor with a new one!

I want the schematic!