Testing VHF RF circuits

[zachtheterrible]

I was wondering if there is any way to test a vhf rf circuit before soldering the whole thing together. I have a breadboard, and have assembled the circuit on it, but it doesn't work because of capacitance issue. I've thought of just alligator clipping the leads together. Would that work, or would the long leads lead to another capacitance issue?

 

[Russlk]

With VHF, there is no substitute for a PC board. You could use perfboard and solder the leads together (short leads) but you would not have a ground plane. I have built circuits on copper clad board using glass bead standoffs. This works OK up to about 300 mHz but for higher frequencies a PC board using surface mount parts will work best.

 

[zachtheterrible]

thanx.

 

[k7elp60]

Testing VHF circuits

I have had good luck building RF circuits up to and including VHF on a blank piece of copper clad board, by soldering the parts directly to the
copper side. For example if you have a circuit that has a resistor from emitter to ground. Cut on lead of the resistor to about 1/4" long, bend it at a right angle to the body of the resistor. Solder that end to the copper. the resistor is now vertical. Cut the other lead short and solder the emitter of the transistor to the resistor. I have used TO-18 case transistors and turned them upside down, bent the leads, and in some cases even soldered the emitter's to the copper. You can solder one lead
of bypass capacitors to ground and use the other lead for positive voltage
connections. Just some idea's that may help

 

[Pilot]

Testing VHF circuits

k7elp60

Typical 'Ugly style' construction and very easy to knock up a prototype in a short time.

I don't do much vhf building but with care in layout decent results should be had.

This reminds me that I have a couple of Doug DeMaw circuits to build and 'ugly' would be the best method.

Enjoy.