Copperless perfboard + wire wrap for RF prototyping?

[hendorog]

Here is a good example of RF lego, will need a fairly fat wallet though!

https://www.xmicrowave.com/

[Canis Dirus Leidy]

I can't get on with that. I use a Stanley knife, metal ruler and peel the strips off with pliers.

The “classical” technique involves the use of a simple device made of a brass spacer and two old dental drills:

(Photos taken from here)
But of course, there are many options. From spade drills, to homemade burrs from a thin-walled steel tube.

[tggzzz]

One other question: I have no single sided board at the moment, but I have some veroboard. Will I have any joy using the copper side of the veroboard as a makeshift ground plane by bridging the tracks with wire, and using dead bug construction on the other side? Or is there too little copper to make this worthwhile?

Depends on the frequencies involved. (Remember, for digital signals, the frequency is defined by the risetime, not the period.)

Any wire is an inductor, rule of thumb 1nH/mm, but a broad flat trace will have a lower inductance.

Any two parallel wires form a capacitor and a transformer.

There are calculators available to estimate the magnitude of the effects.

[fourfathom]

Of course Amazon has a wide assortment of inexpensive single and double-sided clad boards, perfboards, etc.  Get the fiberglass (FR4) boards, not the phenolic ones.  I've purchased these before and they were fine:
https://www.amazon.com/uxcell-150x100mm-Double-Sided-Thickness-Prototyping/dp/B07R49DXN8/

[aneevuser]

In the light of the postings above, I'm just going to confirm that wireless breadboard is absolutely insidious when it comes to constructing resonant circuits: I've largely ignored the advice above, and I've continued to play around with tank circuits on breadboard, which I've been driving from a sig. gen. through a fixed resistor (I've been swapping in different values to see how it affects Q). These have been behaving largely as expected.

This afternoon, I swapped the fixed resistor for a variable, and I was baffled to see that I was now getting voltage gain from the top of the tank. It took me over an hour to figure out that in fact I'd managed to construct a series LC circuit, where the series C was due to the capacitance between the legs of the variable resistor which were in adjacent rows of the board - in fact, the circuit worked unchanged if I removed the resistor completely, and merely relied on the capacitive coupling between the rows.

This is, on the one hand, painful, and on the other, very instructive.

[tggzzz]

In the light of the postings above, I'm just going to confirm that wireless breadboard is absolutely insidious when it comes to constructing resonant circuits: I've largely ignored the advice above, and I've continued to play around with tank circuits on breadboard, which I've been driving from a sig. gen. through a fixed resistor (I've been swapping in different values to see how it affects Q). These have been behaving largely as expected.

This afternoon, I swapped the fixed resistor for a variable, and I was baffled to see that I was now getting voltage gain from the top of the tank. It took me over an hour to figure out that in fact I'd managed to construct a series LC circuit, where the series C was due to the capacitance between the legs of the variable resistor which were in adjacent rows of the board - in fact, the circuit worked unchanged if I removed the resistor completely, and merely relied on the capacitive coupling between the rows.

This is, on the one hand, painful, and on the other, very instructive.

Excellent

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!

[aneevuser]

Excellent

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!

Right. I'm really Mr Theoretical (more at home with the Feynman Lectures than a soldering iron-kinda-guy) and even getting a tank circuit to work reliably at AM frequencies on breadboard is giving me a right schooling in practical circuit construction. And I'm finally beginning to understand why my past attempts at RF circuitry have failed - those stray Ls and Cs the books drone on about really make a difference, kiddies!

[tggzzz]

Excellent

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!

Right. I'm really Mr Theoretical (more at home with the Feynman Lectures than a soldering iron-kinda-guy) and even getting a tank circuit to work reliably at AM frequencies on breadboard is giving me a right schooling in practical circuit construction. And I'm finally beginning to understand why my past attempts at RF circuitry have failed - those stray Ls and Cs the books drone on about really make a difference, kiddies!

Yes indeed!

Wait until you look at microwave circuit elements, e.g. stripline filters where the inductors don't have loops and the capacitors are just inductors with a different aspect ratio

The combination of theory and practice is more exciting than either on its own.