Where to get some board-edge BNC jacks/part number?

Jeroen Belleman <jeroen@nospam.please> wrote in
news:r7bjkh$1ohi$1@gioia.aioe.org:

On 2020-04-16 23:05, Lasse Langwadt Christensen wrote:
torsdag den 16. april 2020 kl. 22.44.37 UTC+2 skrev Jeroen
Belleman:
On 2020-04-16 19:02, Lasse Langwadt Christensen wrote:
[...]

I've tried buying some real cheap SMAs you could melt the
isolation. it is supposed to be PTFE so that shouldn't be
possible


Which were those please? I have uses for SMA connectors without
teflon.


I don't remember it was quite a while ago, bought dirt cheap from
some random webshop

why no ptfe?


I'd use them in particle accelerators. Radiation does bad things
to teflon. Polyethylene and polystyrene fare much better.

Jeroen Belleman

There are exactly ZERO teflon sheathed wires in a nuclear reactor.

It turns teflon to a powder. I wonder how delrin fares.

 

On Fri, 17 Apr 2020 09:53:58 +0200, Arie de Muynck
<no.spam@no.spam.org> wrote:

On 2020-04-17 08:50, Jeroen Belleman wrote:
I'd use them in particle accelerators. Radiation does bad things
to teflon. Polyethylene and polystyrene fare much better.

Jeroen Belleman

Hi Jeroen,

I just bought 40 of these, for EUR 0.15 a piece, the cheapest I could
find in that shape, for use at 868MHz. I just tested one: it does not
melt at 380C. I think you will have a hard time finding non-PTFE versions...

https://www.aliexpress.com/item/32948380887.html

Regards,
Arie de Muijnck

Search Amazon for "edge-launch SMA connector." Ones that look just
like your link cost a dollar or less with free Prime shipping.

https://www.amazon.com/Female-Socket-Mount-Adapter-Connectors/dp/B07QH6TWRY/ref=sr_1_10?crid=13V5PPHXOG5MG&dchild=1&keywords=edge-launch+sma+connector&qid=1587134255&sprefix=edge+launch+sma%2Caps%2C201&sr=8-10

That's incredible.

The fat center pin adds capacitance that matters for really fast
stuff. Just the connector pins in free space, no PCB, are below 100
ohms. We did an ATLC em simulation to optimize PCB stackup. If you cut
away all internal PCB planes near the center pin, and put ground on
the bottom only, it's pretty good.

https://www.dropbox.com/s/eg98x25glp3yn6p/Edge%20Launch%20Connector_small.bmp?raw=1

https://www.dropbox.com/s/hebu7yfzj9mf3lm/Rob1.jpg?raw=1

https://www.dropbox.com/s/1zb71vy9g576c6y/E-field.jpg?raw=1

The more serious microwave SMAs have a tiny flat center pin. We are
about to test some layouts.

https://www.dropbox.com/s/qwowjio5l9eubsp/Z482_TX_Lines.jpg?raw=1









--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Arie de Muynck]

On 2020-04-17 16:50, jlarkin@highlandsniptechnology.com wrote:

On Fri, 17 Apr 2020 09:53:58 +0200, Arie de Muynck
no.spam@no.spam.org> wrote:

I just bought 40 of these, for EUR 0.15 a piece, the cheapest I could
find in that shape, for use at 868MHz. I just tested one: it does not
melt at 380C. I think you will have a hard time finding non-PTFE versions...

https://www.aliexpress.com/item/32948380887.html

Regards,
Arie de Muijnck

Search Amazon for "edge-launch SMA connector." Ones that look just
like your link cost a dollar or less with free Prime shipping.

https://www.amazon.com/Female-Socket-Mount-Adapter-Connectors/dp/B07QH6TWRY/ref=sr_1_10?crid=13V5PPHXOG5MG&dchild=1&keywords=edge-launch+sma+connector&qid=1587134255&sprefix=edge+launch+sma%2Caps%2C201&sr=8-10

That's incredible.

Yes, I find the Amazon prices incredible too, often more 3 times the
AliExpress price. I just try to guess what stock I will need in the
future, so I can wait the extra month for delivery to the Netherlands.
I'm not pressed for time anymore. And, since I only use them for 868 MHz
the quality is good enough (contact resistance and robustness is more
important than SWR at that 'low' frequency). And they did not have bent
pins like the one on the Amazon picture .

The fat center pin adds capacitance that matters for really fast
stuff. Just the connector pins in free space, no PCB, are below 100
ohms. We did an ATLC em simulation to optimize PCB stackup. If you cut
away all internal PCB planes near the center pin, and put ground on
the bottom only, it's pretty good.

https://www.dropbox.com/s/eg98x25glp3yn6p/Edge%20Launch%20Connector_small.bmp?raw=1

https://www.dropbox.com/s/hebu7yfzj9mf3lm/Rob1.jpg?raw=1

https://www.dropbox.com/s/1zb71vy9g576c6y/E-field.jpg?raw=1

For very critical analysis you might add the center pin solder fillet.

The more serious microwave SMAs have a tiny flat center pin. We are
about to test some layouts.

https://www.dropbox.com/s/qwowjio5l9eubsp/Z482_TX_Lines.jpg?raw=1

On that PCB, I do expect reflections by impedance discontinuities at the
intermediate locations, like when testing from J11 to J10 at the
J27,28,29 pads. Isn't that more critical than the difference between
round and flat pin? Why not add GND traces with the same width as the
pads, to prevent these discontinuities?

Regards,
Arie de Muijnck

 

On Sat, 18 Apr 2020 16:59:51 +0200, Arie de Muynck
<no.spam@no.spam.org> wrote:

On 2020-04-17 16:50, jlarkin@highlandsniptechnology.com wrote:
On Fri, 17 Apr 2020 09:53:58 +0200, Arie de Muynck
no.spam@no.spam.org> wrote:

I just bought 40 of these, for EUR 0.15 a piece, the cheapest I could
find in that shape, for use at 868MHz. I just tested one: it does not
melt at 380C. I think you will have a hard time finding non-PTFE versions...

https://www.aliexpress.com/item/32948380887.html

Regards,
Arie de Muijnck

Search Amazon for "edge-launch SMA connector." Ones that look just
like your link cost a dollar or less with free Prime shipping.

https://www.amazon.com/Female-Socket-Mount-Adapter-Connectors/dp/B07QH6TWRY/ref=sr_1_10?crid=13V5PPHXOG5MG&dchild=1&keywords=edge-launch+sma+connector&qid=1587134255&sprefix=edge+launch+sma%2Caps%2C201&sr=8-10

That's incredible.

Yes, I find the Amazon prices incredible too, often more 3 times the
AliExpress price.

I meant incredibly low. Under $1 for an gold plated SMA edge-launch,
with shipping, is effectively free.




I just try to guess what stock I will need in the

future, so I can wait the extra month for delivery to the Netherlands.
I'm not pressed for time anymore. And, since I only use them for 868 MHz
the quality is good enough (contact resistance and robustness is more
important than SWR at that 'low' frequency). And they did not have bent
pins like the one on the Amazon picture .

The fat center pin adds capacitance that matters for really fast
stuff. Just the connector pins in free space, no PCB, are below 100
ohms. We did an ATLC em simulation to optimize PCB stackup. If you cut
away all internal PCB planes near the center pin, and put ground on
the bottom only, it's pretty good.

https://www.dropbox.com/s/eg98x25glp3yn6p/Edge%20Launch%20Connector_small.bmp?raw=1

https://www.dropbox.com/s/hebu7yfzj9mf3lm/Rob1.jpg?raw=1

https://www.dropbox.com/s/1zb71vy9g576c6y/E-field.jpg?raw=1

For very critical analysis you might add the center pin solder fillet.

The more serious microwave SMAs have a tiny flat center pin. We are
about to test some layouts.

https://www.dropbox.com/s/qwowjio5l9eubsp/Z482_TX_Lines.jpg?raw=1

On that PCB, I do expect reflections by impedance discontinuities at the
intermediate locations, like when testing from J11 to J10 at the
J27,28,29 pads. Isn't that more critical than the difference between
round and flat pin?

Those boards (we have six) will be sheared up into a bunch of txline
experiments of various length. J27-28-29 might make minor
discontinuities in TDR, but that's the worst part of the layout, with
cheap connectors. I don't think the intermediates will have much
effect on overall TDT wave shape. We could always hack them too.

Why not add GND traces with the same width as the
>pads, to prevent these discontinuities?

That would make this a coplanar waveguide experiment. We might try
that some day. The immediate problem is to help us decide when FR4 is
good enough for microstrip circuits.

On the more serious microwave connectors, the center pins are tiny,
which is more important than their shape.

The serious microwave ones, like J7, have more distance between the
ground pins. A coplanar waveguide with that spacing is
indistinguishable from a plain microstrip.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Arie de Muynck]

On 2020-04-18 18:34, jlarkin@highlandsniptechnology.com wrote:

On Sat, 18 Apr 2020 16:59:51 +0200, Arie de Muynck
no.spam@no.spam.org> wrote:

The more serious microwave SMAs have a tiny flat center pin. We are
about to test some layouts.

https://www.dropbox.com/s/qwowjio5l9eubsp/Z482_TX_Lines.jpg?raw=1

On that PCB, I do expect reflections by impedance discontinuities at the
intermediate locations, like when testing from J11 to J10 at the
J27,28,29 pads. Isn't that more critical than the difference between
round and flat pin?

Those boards (we have six) will be sheared up into a bunch of txline
experiments of various length. J27-28-29 might make minor
discontinuities in TDR, but that's the worst part of the layout, with
cheap connectors. I don't think the intermediates will have much
effect on overall TDT wave shape. We could always hack them too.

Why not add GND traces with the same width as the
pads, to prevent these discontinuities?

That would make this a coplanar waveguide experiment. We might try
that some day. The immediate problem is to help us decide when FR4 is
good enough for microstrip circuits.

On the more serious microwave connectors, the center pins are tiny,
which is more important than their shape.

The serious microwave ones, like J7, have more distance between the
ground pins. A coplanar waveguide with that spacing is
indistinguishable from a plain microstrip.

I see. Interested to see the TDR results.

I assume the GND planes under the wide and narrow tracks are on
different depths to get the same impedance? That would give a nice
indication on FR4 and track width performance. Less FR4 depth = less
loss, but narrower copper track = more loss? It might compensate.

Regards,
Arie de Muijnck

 

On Sun, 19 Apr 2020 13:45:51 +0200, Arie de Muynck
<no.spam@no.spam.org> wrote:

On 2020-04-18 18:34, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Apr 2020 16:59:51 +0200, Arie de Muynck
no.spam@no.spam.org> wrote:

The more serious microwave SMAs have a tiny flat center pin. We are
about to test some layouts.

https://www.dropbox.com/s/qwowjio5l9eubsp/Z482_TX_Lines.jpg?raw=1

On that PCB, I do expect reflections by impedance discontinuities at the
intermediate locations, like when testing from J11 to J10 at the
J27,28,29 pads. Isn't that more critical than the difference between
round and flat pin?

Those boards (we have six) will be sheared up into a bunch of txline
experiments of various length. J27-28-29 might make minor
discontinuities in TDR, but that's the worst part of the layout, with
cheap connectors. I don't think the intermediates will have much
effect on overall TDT wave shape. We could always hack them too.

Why not add GND traces with the same width as the
pads, to prevent these discontinuities?

That would make this a coplanar waveguide experiment. We might try
that some day. The immediate problem is to help us decide when FR4 is
good enough for microstrip circuits.

On the more serious microwave connectors, the center pins are tiny,
which is more important than their shape.

The serious microwave ones, like J7, have more distance between the
ground pins. A coplanar waveguide with that spacing is
indistinguishable from a plain microstrip.

I see. Interested to see the TDR results.

Our real question is how far we can run a 50 ohm trace on FR4 and get
a decent x picosecond rise time, and also which connectors work better
to deliver that edge.

We'll do some experiments and write it up. I'll post it here. It may
take a while, given the current chaos.

If we don't like the numbers, we might try some microwave laminates.
Right now, we want to drive a Mach-Zender modulator with a roughly 50
ps wide pulse, and the critical PCB trace is longer than we'd prefer,
a bit over half an inch long.

I assume the GND planes under the wide and narrow tracks are on
different depths to get the same impedance?

Yes. The two on the right have the general plane, 25 mils below the
surface. That transitions to full-board, 62 mils, ground for the two
on the left.

That would give a nice

indication on FR4 and track width performance. Less FR4 depth = less
loss, but narrower copper track = more loss? It might compensate.

I think that less depth is more loss. Might multiply.

Regards,
Arie de Muijnck

Our experience suggests that the ones on the left will be better.
Wider traces have less skin loss. Cheap FR4 boards are dominated by
skin loss; the current density is mostly on the bottom of the layer 1
foil, and the bottom has the drecky black oxide treatment for
adhesion.





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Michael Terrell]

On Thursday, April 16, 2020 at 7:23:32 PM UTC-4, bitrex wrote:

On 4/16/2020 7:18 PM, bitrex wrote:
On 4/16/2020 12:44 PM, jlarkin wrote:
On Thu, 16 Apr 2020 00:13:20 -0400, bitrex <user@example.net> wrote:

On 4/15/2020 11:56 PM, John Larkin wrote:
On Wed, 15 Apr 2020 23:33:01 -0400, bitrex <user@example.net> wrote:

Looking for those board-edge jacks e.g. Mr. Larkin uses with the two
solder-lugs that can be grounded to the plane. Part number at
Mouser/Newark would be great if you got it.

The Vbites?

MFR1   BOMAR CON           361V509E
MFR2   ALLIED              202-0450
MFR3   MOUSER              678-361V509E
MFR4   NEWARK              80K0248

One thing to be careful about is the PCB thickness. Go for 64 mils
max. Deleting the solder mask in the mating area can buy a couple of
mils.





Those are nice, but I had more in mind the type I see you use on
copper-clad manhattan-style protos, that have the two lugs coming out
parallel to the connector barrel and then solder-blob those to the
board.

Maye they aren't BNC I can't recall what the end termination was, now....

Try Amazon or ebay. They have all sorts of cool connectors.

Amazon has lots of edge-launch SMAs, crazy cheap.



All Amazon shipments of "non-essentials" are delayed for me, I don't
think they consider connectors "essential."

As of last night shortest Prime shipping-time on stuff like that to my
location, usually two-day, was about a week, some stuff I usually get
there too like SOIC "surfboards" they're estimating a month.


I managed to get my hands on some of these from the local
brick-and-mortar parts store which is thankfully (reasonably!)
considered "essential" and still doing curbside pick-up from the loading
dock. It'll have to do for now:

https://www.arcade-electronics.com/952NP-Philmore-BNC-Connector-Chassis-Mount-Female-p/phi-952np.htm

Philmore? Their stuff used to be worse than Calrad's early Japanese crapnectors.


They have been around for a very long time. One early product was Galena crystals an cat whiskers.