Breadboarding at RF

[CopperCone]

If you think that bronx is ugly chances are your handtools are not up to snuff.

I recommend you have a good look through say the swanstrom catalog to find nice hand tools to work with.

Hand tools are important, remember that time travel episode of startek TOS? You also want a fine vise (I have a mini machinists vice and several watch makers vise) to hold things in place. The watchmakers vise is the size of a silver dollar.

I think the problem is that you can work extremely rapidly to throw some shit together. Like any other skilled craft, you can make things alot nicer if you want to. You can solder resistors to each other with 45 degree cut leads (like a needle) so that they match nicely and have what appears to be a single wire connection if you want. Much better then the twist&solder or parallel solder that most people do. If you are willing to go under the microscope you can make structures that appear nice for mating three or more components together at what looks like a solid connection... remember you can set everything up on mini clamps, over solder, then use a wick to very carefully remove solder.

A microscope/heavy magnitifer and jewelers files are useful too (like diamond mini files).

[Wolfgang]

same discussion as the one about Stalinistic shielding. Cliches and Metaphors are determined by your social background.  Here in Europe the Bronx is deemed less nice than Manhattan
What is meant is that maximum care should be spent on "electrical" beauty, with niceness only where it does not hurt

[CopperCone]

Well I thought manhattan being rich ass socialites basically used the equivalent of table coasters, so their fine french finish on the 5000$ coffee table is not stained (manhattan style)

while bronx style is basically some poor guy having a hot dog on the street and they don't care if they stain the sidewalk ... or at least they are not Bourgeoisie enough to use coasters.

Manhattan style from what I under stand is more like the style used for high impedance connections and bronx is classical 'deadbugging'

I thought for manhattan style they sell little pads that you are supposed to glue down to the copper clad board to act as islands. Bronx you typically would give it a twist and solder or just bring them kinda close together and join with a solder bead...

whereas I am saying to do fine work like miter your component lead cuts, clamp them in a vise, carefully join with the minimum of solder and then remove or even file away excess solder to make yourself a seamless looking connections (I have yet to see anyone publish this method). I mean you can even polish your solder joints if you want.. I am just saying you can make something typically ugly look really nice....


And if soldering is anything like brazing, you theoretically SHOULD have some kind of jigs to hold things together.. if you look at braze strenght curves, you will see that for good brazing you want to really precisely align up your parts, use shims to determine if the spacing is correct (might be somewhere like 5 thousandths of an inch, it depends on all sorts of factors) then apply braze for maximum strength.... but again it does not matter at all with soldering.. maybe the joints are statistically less reliable.

When I think typical bronx I imagine some guy holding parts together and touching them with a soldering iron held in his mouth!

[Wolfgang]

... and I was naive and thought the "Manhattan" came from mounting all components upright like Manhatten skyscrapers 

[CopperCone]

its a specific style where you use PCB board punch outs to act as connector islands. I think the rational is that it looks like manhattan from a view of how the 'foundations' are planted.

The next step would be 'D.C.' style construction where you make sketches and do pre-design work on the layout so its like a planned community layout, like washington DC.

[HB9EVI]

I was quite disgusted by the look of a lot of manhatten style projects; and it was obvious to not be much RF compatible. I adopted the 'drilling island' system mentioned by om Hans DJ1UGA using a Dremel cutter like this https://www.dremeleurope.com/ch/de/fraeser-hss-6-4mm-135-ocs-p/ . they sell in different diameters, drilling appropriate islands to solder SOT23 transistors and 0806 Rs and Cs. that's really very neat to build good RF circuits; I used the technique for 5 band HF-transceiver together with basic through hole components like crystals and some dip8 as dead bugs

[Wolfgang]

Maybe the proper name for the many island styles would be "polynesian" style 

I think all styles are OK as long as "electrical beauty" (.i.e. minimal parasitics and unwanted coplings) is honoured. The rest is a matter of taste.
Manhatten is definitely not the best for high frequencies due to redundant wire lengths caused by the all-upright mounting method.

The ideal mounting style is the one where all components are connected just by soldering joints at their ends (no longer leads), or, if not possible,
by defined impedance transmission line segments.

The technique to drill islands into a copper plane is OK, but not as flexible regarding circuit modifications as the pure Bronx.

[HB9EVI]

agreed! it requires a bit of planning, since afterward mods are tricky - but still not impossible. In every case it's in the meantime my favorite way of construction.

I like calling it the 'polynesian style'

[bd139]

Interesting thread this.

For TH, I’ve been using a variation of Manhattan style which relies on the components being mounted almost legless and flat between the islands which are carefully spaced to make sure there is just enough room. This removes all those neat but electrically horrible excess inductors everyone leaves on one end of a component and decreases the weight of the final assembly. Similar to what you found in old point to point wired equipment but without the rat’s best.

I call this Endor style after the Ewok’s tree houses in Star Wars.

BUT honestly there’s not much point in using crappy old TH components now for ham stuff at least unless it’s high power now. And almost definitely not for anything VHF and above. And manhattan is ugly as sin and extremely difficult to modify once done because of all the glue stuck all over the ground plane.

Just draw the sub unit schematic out (say an LPF), cut some square islands in FR4 with an X-Acto and just bridge the gaps. No messy glue, cheaper and smaller. SMD stuff costs bugger all as well, even the brand name stuff. When you have a sub assembly working, glue that to another bit of FR4. It also acts as a very convenient low impedance star topology ground.

Typical module (10Mhz VCTCXO + power supply):

[Wolfgang]

SMD is great for people with eagles eyes and very steady hands (not me).
For this reason, a lot of prototypers still prefer thru-hole components if frequency range permits.
In case I really needed SMD stuff for performance reasons, I made a PCB, too.

For UHF and above, the PCB becomes part of your circuit anyway and must be taken into account if you want a repeatable result. 

[tggzzz]

For UHF and above, the PCB becomes part of your circuit anyway and must be taken into account if you want a repeatable result. 

Very true.

Unfortunately too many people with modern logic operating at 1Hz don't realise that is also operating at UHF!

[dmills]

Clock frequency does not matter, edge rates do!

[bd139]

Fortunately most logic families are relatively forgiving of misuse

[Wolfgang]

The "fastest" logic family I was able to make a Bronx style circuit with was an 80MHz LFSR using 5 ACMOS chips.
When I tried to do the same with ECL100K and 200MHz it never reliably worked, despite using 50Ohm striplines.
After making a PCB with controlled impedance tracks and terminators it finally worked.

On the other hand, I was able to make a working 23cm two-stage amplifier using MMICs and striplines on a Bronx-Style backplane.

https://electronicprojectsforfun.wordpress.com/prototyping/

So, my experience is that fast logic is even *less* tolerant to construction style than plain analog !

[HB9EVI]

Fast logic (74AC) I still got running at 120MHz as dead bugs to create the phase shift for an I/Q mixer without issues. Analog worked out so far in polynesian style up to the 23cm band on FR4.
I'm normally simply too lazy to layout a pcb and etch it

[Wolfgang]

The simpler the circuit, the better the chance to get away with suboptimal wiring. 120MHz for 74AC in a very simple circuit with 1-2 ICs might work. An LFSR with 5 ICs all in the signal path is on the edge regarding gate delays and setup times. If reflections and ringing gets on top of that, it is likely to fail at higher frequencies. I tried 100MHz and it failed, even on a nice PCB.

Just to see how far you could go you could check out the multi-GHz ugly construction cicuits from LY3LP:
http://laboratory1475.rssing.com/chan-34446832/latest.php

[james_s]

If you need a LFSR running at 10s of MHz it starts to make a lot more sense to use a CPLD. In a sense that's like a very small breadboard with very short connections.

[Wolfgang]

Yeah, agreed. I planned to do that, but I was held up by other tasks. What CPLD type would you recommned for a 32Bit register, and what would be a realistic clock frqeuency ?

[james_s]

You'd have to look at the datasheets, I'm not up to date with what's currently on the market nor have I tried pushing the limit with the clock frequency. I've used the Xilinx XC9536XL and a similar Altera part (Max II?), the dev boards are cheap so you could pick one up to try it out, something like this https://www.ebay.com/itm/Altera-FPGA-programmatore-CPLD-USB-Blaster-compatibile-LC-MAXII-EPM240/172477210445?

If you need a hand with the code I could whip up some VHDL for you if you have a schematic of the LFSR you want.

[tggzzz]

The simpler the circuit, the better the chance to get away with suboptimal wiring. 120MHz for 74AC in a very simple circuit with 1-2 ICs might work. An LFSR with 5 ICs all in the signal path is on the edge regarding gate delays and setup times. If reflections and ringing gets on top of that, it is likely to fail at higher frequencies. I tried 100MHz and it failed, even on a nice PCB.

Even a simple circuit will fail, if there is a heavy load and "long" ground leads: ground bounce can be a serious problem.

[cdev]

Its easier to use a short length of mini coax than a PC trace sometimes, while keeping the PCB attached at both ends for the extra groundplane. You get the best of both worlds that way. Its quieter.