High frequency via pls jumper? - Page 1
Forum section: electronics / beginners

author: mpp2508
author_rank: Contributor
timestamp: August 30, 2025, 09:55:41 am
content: Here is a module on AD9833 and a module of a bnc connector connected by jumpers. Maybe someone will tell me at what frequencies approximately this will become a problem. Is there any sense in looking for a higher frequency solution?

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 31, 2025, 07:02:40 am
content: I guess it may be quite properly investigatet with a VNA if you have such.If you really work with HF/UHF you definitely should have a VNA.But, AD9833 isn't really high frequency device. As I see it is 12 MHz device - that's not really high. Possibly those jumpers are good enough for this frequency range.

author: amyk
author_rank: Super Contributor
timestamp: August 31, 2025, 08:03:03 am
content: I don't know what an AD8933 is but if it's a clone of the '9833 then that only goes up to 12.5MHz, for which those jumpers will be fine.

author: mpp2508
author_rank: Contributor
timestamp: August 31, 2025, 11:42:42 am
content: Quote from: amyk on August 31, 2025, 08:03:03 amThis is about AD9833. There is an error in the silkscreen.

author: mpp2508
author_rank: Contributor
timestamp: August 31, 2025, 12:53:10 pm
content: Quote from: amyk on August 31, 2025, 08:03:03 amIn fact, the question is somewhat deeper. A similar module will be for Si5351, where it is already 160 MHz. Also other future modules compatible with mpp2508. Yesterday I looked for various options for RF connectors, and chose MHF4/ipex4. The option of installing PLS and MHF4 seems inconvenient, and I don’t know how to combine them. And to connect different modules, use an adapter.The question is, from what frequencies should MHF4 be used, and for what is PLS enough?

author: David Hess
author_rank: Super Contributor
timestamp: August 31, 2025, 02:07:42 pm
content: The three jumpers are continuing the transmission line so that will work to better than 100 MHz. Some of the older 100+ MHz Tektronix oscilloscopes have similar construction.

author: mpp2508
author_rank: Contributor
timestamp: August 31, 2025, 04:03:51 pm
content: Quote from: David Hess on August 31, 2025, 02:07:42 pmThat is, the frequency of the transition from PLS to MHF4 can be taken as 100 MHz?

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 31, 2025, 05:40:48 pm
content: Ready-made modules with Si5351 are mostly equipped with a SMA connectors, as I can see on Google-pictues.

author: mpp2508
author_rank: Contributor
timestamp: August 31, 2025, 07:28:09 pm
content: Quote from: Vovk_Z on August 31, 2025, 05:40:48 pmFor my modules SMA is not suitable due to its dimensions.

author: fourfathom
author_rank: Super Contributor
timestamp: August 31, 2025, 08:40:56 pm
content: Those jumpers should be fine for signal integrity. They will probably create a small impedance mismatch, but unless you look very carefully you won't notice that until you are well past the 100 MHz point. I make filters and preamps used in SDR systems and often use those jumpers to select or bypass filter sections. Filter attenuation curves look reasonable up through 1 GHz -- layout and component parasitics have a much larger effect than the jumpers.

author: mpp2508
author_rank: Contributor
timestamp: September 01, 2025, 05:02:30 am
content: Then another question. These modules may not be installed tightly to connect them with jumpers. In mpp2508 modules can be connected with dupont jumpers. Accordingly, it is necessary to determine up to what frequency dupont can be used, and with what frequency a shielded cable can be used, for example. As it seems to me, even 50 MHz is too much for dupont jumpers.

author: amyk
author_rank: Super Contributor
timestamp: September 01, 2025, 06:04:02 am
content: Note thathttps://en.wikipedia.org/wiki/Parallel_ATAused the same connector with ribbon cables up to effective clock speed of 16.7MHz, and when the 20MHz and 33MHz version came out (ATA66) retained the same connector but required a cable in which every other wire was ground.

author: mpp2508
author_rank: Contributor
timestamp: September 01, 2025, 07:51:48 am
content: In general, in the end, this is the module on Si5351.

author: fourfathom
author_rank: Super Contributor
timestamp: September 01, 2025, 03:16:03 pm
content: Those U.FL connectors will certainly do the job. I've used those with SMA on the other end of the cable, and I see that you can get U.FL to BNC jumpers. The Si5351 will drive a 50 Ohm cable, but the impedance match may not be perfect (which may not matter in your application?) When I interface the Si5351 to the outside world I do it via a buffer stage with resistive impedance-setting and some transient protection.

author: tszaboo
author_rank: Super Contributor
timestamp: September 01, 2025, 03:21:31 pm
content: What's this prototyping system called? Are you developing it yourself?

author: mpp2508
author_rank: Contributor
timestamp: September 01, 2025, 04:22:37 pm
content: Quote from: tszaboo on September 01, 2025, 03:21:31 pmmpp2508 - modular portable prototyping (2mm hole, 5.08 pitch)https://www.eevblog.com/forum/projects/modular-portable-prototyping/https://mpp2508.github.io/docs/02m/00gal/- gallery of modules

author: mpp2508
author_rank: Contributor
timestamp: September 02, 2025, 12:05:37 pm
content: Quote from: tszaboo on September 01, 2025, 03:21:31 pmMaybe some questions have arisen?

author: tszaboo
author_rank: Super Contributor
timestamp: September 03, 2025, 01:15:57 pm
content: Quote from: mpp2508 on September 02, 2025, 12:05:37 pmYes. It looks interesting, I hope you will have success developing and marketing it.You probably want to make an output with SMA connector, and a transmission line PCB and measure S12 to see how it behaves at high frequency. Do you have a VNA, like any of the nanoVNA?

author: mpp2508
author_rank: Contributor
timestamp: September 03, 2025, 02:05:56 pm
content: Quote from: tszaboo on September 03, 2025, 01:15:57 pmThis is an open source project. The most I can hope for is if someone decides to support it on Patreon, and that's because the module prototypes are a bit expensive, but they are made with my own money, but there are a lot of modules. And there are also several iterations. I'm currently working on standardization. And I really need feedback. Even information on why they won't use this approach to prototyping.I don't have nanoVNA, and I'm unlikely to have one, since I don't work with high-frequency circuits. I got involved with these connectors because I decided to make a module for assembling a signal generator with a microcontroller, display, and encoder to demonstrate the ability to assemble temporary functional devices from modules.And the BNC connector module was made because it's not always convenient to attach oscilloscope probes to the board. So I bought a couple of Cleqee P1202 cables and made a BNC connector module. Now you don't have to disconnect the probes every time you need to de-energize the prototype and disconnect all the wires to make changes with a soldering iron.

author: ftg
author_rank: Frequent Contributor
timestamp: September 03, 2025, 02:37:46 pm
content: I do like this mpp2508 format and might take a look at making some modules of my own in the future.I took a quick look atthe Github page, but did not find a template.But the documentation onhttps://mpp2508.github.io/is quite good, especially about the mechanical dimensions and positioning.If the baseplate gerbers are available, I'll be throwing that into my next JLCPCB order.

author: mpp2508
author_rank: Contributor
timestamp: September 03, 2025, 03:34:17 pm
content: Quote from: ftg on September 03, 2025, 02:37:46 pmI added the archive, the one I ordered last time.https://github.com/mpp2508/mpp_bs2020/tree/main/alt/outIf you are interested in something else, write to GitHub in ' Issues ', of a specific module.If there is no module, but you think it would be nice to have it, you can probably write ' Issues 'https://github.com/mpp2508/mpp2508.github.ioAlso for all other questions not related to specific modules.There is also an opportunity to discuss all this on Patreon, but I don't want to be distracted by several platforms, and it is too early to create a site with a forum. Unless someone agrees to allocate a section for the ability to create subtopics. But this is also too early.

author: tszaboo
author_rank: Super Contributor
timestamp: September 03, 2025, 10:18:50 pm
content: Quote from: mpp2508 on September 03, 2025, 02:05:56 pmYou can connect a scope probe to a BNC connector with an adapter:CAL TEST ELECTRONICS - CT2708For me the only "bummer" is that the mounting hole is 5.08mm, not 5. I place my mounting holes on exact 10mm distances usually. Which might just work.

author: radiolistener
author_rank: Super Contributor
timestamp: September 04, 2025, 01:19:11 am
content: Quote from: mpp2508 on August 30, 2025, 09:55:41 amThe practical answer largely depends on the level of signal distortion you are willing to accept. The AD9833 itself does not provide a very high-purity output, and with short jumper connections like in your setup, the arrangement can be adequate for sinewave signals up to roughly 50-100 kHz. Beyond that, or when generating other waveforms such as square or triangular outputs, significant degradation can occur even at lower frequencies. For cleaner or higher-frequency operation, a proper PCB layout, proper transmission line with constant characteristic impedance, filtering, and buffered output would be necessary.Quote from: mpp2508 on September 01, 2025, 05:02:30 amYes, 50 MHz is indeed far too much for 5-10 cm "spaghetti" wires in any controlled RF sense.That said, with some care it is sometimes possible to make such connections work for digital data transfer. For example, I once had a high-speed ADC working at 100 MHz clock connected to an FPGA board using a 10 cm ribbon cable (all wires were exactly the same length) similar to old floppy drive cables, and it did function. The main issue was that the setup was extremely sensitive to the relative placement of the wires - signal integrity depended heavily on phase alignment between traces. By carefully arranging and fixing the wires in a position that balanced the skew within acceptable limits, it was possible to achieve stable operation. Still, this kind of wiring is fragile, error-prone, and requires significant trial-and-error along with good equipment to monitor and verify timing relationships.However, if your goal is to transmit an analog signal at such frequencies without significant distortion, this won’t be feasible with loose jumper wires - or even with a somewhat more stable ribbon cable arrangement. At that point you really need a proper transmission line with controlled impedance, such as a coaxial cable or a correctly designed PCB trace.I should also mention that PLS connectors are generally not reliable for high-frequency signal transmission. They may work reasonably well when new, but the contact quality tends to degrade over time, leading to signal integrity problems. In one of my transceivers, for example, the connection between the synthesizer board and the analog front end was made with this type of connector. Initially it performed acceptably, but after some time (2-3 years) issues began to appear - I now have to constantly reseat the contacts to avoid signal distortion.

author: mpp2508
author_rank: Contributor
timestamp: September 04, 2025, 05:28:03 am
content: Quote from: radiolistener on September 04, 2025, 01:19:11 amI decided to install PLS for modules with an output frequency of up to 100 MHz, if higher - MHF4If the signal is up to 20 MHz, connect with a Dupont jumper. If higher, then a PLS to MKhF4 adapter is installed end-to-end.Here's another thing, I probably didn't consider these signals as analog. Only as clock.And as I said earlier, I don't deal with high-frequency circuits, so if you do, maybe you can tell me what scenarios can be thought up for using mpp2508 in high-frequency circuits, or is it impossible? So to speak, a budget X-Microwave.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: September 04, 2025, 05:35:29 am
content: You can get away with making a short coax with female jumper wire housings on both end. You will get reasonable signal integrity to ~100MHz, as far at repeatability goes.The signal will not be distorted (non-linearity wise), just bandwidth limited, and depending on how the dupont wires line up.Another concern is that AD9833 should have a low pass filter on the output. That takes away the edge of these RF concerns. For practical purposes this DSS can produce up to 3MHz amateur measurement grade signals. You will see the triangular wave degrading (bandwidth issue) and the sine wave amplitude drop as well you’ll start to see the quantization.

author: radiolistener
author_rank: Super Contributor
timestamp: September 04, 2025, 05:49:51 am
content: From my experience, at frequencies above 1-3 MHz reflections already start to become significant, and using “spaghetti” wires instead of properly matched lines can cause noticeable problems. At 5 MHz and above, these effects are quite evident. The issue is not only reflections and phase imbalance - such unshielded, unmatched connections are also highly susceptible to crosstalk and noise (just because transmission line with varying impedance works as a good antenna).You mentioned that the signal will be used as a clock, which is a different matter. Clock signals have strict requirements for signal integrity and phase stability, so it’s much better to distribute them via properly matched and shielded lines, such as coaxial cables, with proper electrical length, rather than using loose jumper wires. For clocks, even a small reflections or crosstalk can lead to jitter and can cause issues even if you use it just for audio DAC.If you are working at frequencies above 5 MHz, it’s better just to forget about using jumper and spaghetti wires altogether. For 50-100 MHz, they are completely unsuitable, as their use will almost certainly lead to serious signal integrity issues. At these frequencies, using "spaghetti" wiring and expecting a working solution is more in the realm of miracles and magic than engineering.In your situation, where the board uses the unfortunate choice of a PLS connector instead of a proper RF connector, I would suggest removing the PLS and directly soldering the board connections with the shortest possible equal-length jumpers. The wires should run close to the board surface and straight rather than looping above it. While this still won’t provide a properly matched transmission line, it will be considerably much better than using loose jumper leads.A better solution would be to remove the PLS connector and replace it with a U.FL connector, then use standard coaxial pigtails for inter-board connections or for interfacing with a BNC/SMA connector. But it may not be always possible, depending on the used PLS pin layout.For clock applications, I would recommend using a standard low-cost Chinese Si5351 module with three SMA connectors. They typically cost only 1-2 dollars but provide a much cleaner clock signal in the 5 kHz to 200 MHz range, with ~1 ns rise time and significantly lower jitter, spurs, and noise compared to this DDS. For even better clock performance, you can use si570, it has much lower jitter.Quote from: mpp2508 on August 31, 2025, 12:53:10 pmWhen distributing a clock signal, the critical factor is not just its frequency but the integrity of its edges and the stability of its phase. Even at low fundamental frequencies, the fast edge transitions contain high-frequency components that require proper impedance control. Therefore, it is advisable to always use a proper RF connector and a PCB layout with controlled impedance, even if the nominal clock frequency is only 10 kHz.Interference and noise coupled into a clock transmission line with varying impedance can introduce significant jitter, which may lead to instability in digital circuits feeded from such a clock, or a degradation of the dynamic range in ADC and DAC.For regular digital GPIO signals, PLS connections can work acceptably up to about 5-10 MHz, and in some cases even higher, depending on the application. For example, I use a 40-pin header connection between two boards (without wires), and for prototyping it has worked acceptably for parallel data transfer at 100 MHz rate. However, this type of connection is not reliable and is unsuitable for long-term production use. As I mentioned earlier, it also functioned when connected through a 10 cm ribbon cable, but this introduced phase imbalance and reflection issues and required careful adjustment of the cable geometry to achieve stable operation.For analog applications, the use of PLS connectors is much less suitable. As I mentioned earlier, in one of my transceivers the synthesizer signal was routed between two boards through a PLS connector. Initially this worked reasonably well, but after a few years problems began to appear - the connector often needs to be reseated, otherwise noise shows up or the signal fails completely.

author: mpp2508
author_rank: Contributor
timestamp: September 04, 2025, 08:29:54 am
content: Quote from: radiolistener on September 04, 2025, 05:49:51 amI considered the SMA connector, but decided that it was too big.I'm thinking of doing the same as x-microwave, but not using an overhead element, but a separate module measuring 1u * 4u (5.08 mm * 20.32 mm), I just need to find some flat spring contacts for the overhead element. Or maybe just a spring-loaded board. But how well it will work needs to be tested with all sorts of expensive devices, which I don't have, and I don't understand this.mpp2508 should be as budget-friendly as possible. Therefore, I would like maximum versatility, with minimal costs. Since the one who will use it is expected to have a large number of these modules, therefore, a slight increase in the cost of a separate module can ultimately greatly affect the overall cost.In general, all this requires research and experiments. In the meantime, I will put MHF4 where there is more than 10 MHz. And a dozen MHF4F-MHF4F jumpers will be added to the Dupont jumper set.I would also like to find a solution for a short MHF4F-MHF4F jumper (5.08 mm), which would be a little elastic to compensate for the size spread (MHF4M can be slightly unevenly soldered, which may be impossible when connecting with a rigid jumper). In the appendix, there is an option on a flexible cable, but it seems to me that this is some kind of rare exclusive design. I can't find MHF4F smd.

author: radiolistener
author_rank: Super Contributor
timestamp: September 04, 2025, 08:57:58 am
content: Regarding duplicating RF connectors and PLS, I would advise caution. On Chinese Si5351 boards, this often causes ringing due to the lengths of the branches. While this may not be critical for less sensitive applications, the ringing is noticeable, and I have even considered cutting the pcb trace leading to the PLS connector to reduce it.

author: ftg
author_rank: Frequent Contributor
timestamp: September 04, 2025, 09:15:36 am
content: Quote from: mpp2508 on September 03, 2025, 03:34:17 pmThank you, I'll be ordering some when some other designs get done.Quote from: mpp2508 on September 04, 2025, 08:29:54 amIf there is some mass market product that uses contacts similar to Samtech FSI, then that might be an option for a low profile spring contact.https://www.samtec.com/products/fsiPower connectors for mobile phones and laptops in similar styles to Samtech OPP or SIB might also be available, but might have too high profiles and not be significantly better than 2.54mm jumpers.https://www.samtec.com/products/sibhttps://www.samtec.com/products/oppQuote from: radiolistener on September 04, 2025, 08:57:58 amI have often cut those annoying stubs off myself when using those Chinese MS5351/Si5351 modules.

author: mpp2508
author_rank: Contributor
timestamp: September 04, 2025, 09:22:41 am
content: Quote from: radiolistener on September 04, 2025, 08:57:58 amThere was a thought about duplication, but it lived for a moment. Even my knowledge is enough to understand that I should not get involved with such a decision.