Nice project with the ferrite setup. I put Super glue on a component on a PCB then soldered the component connection. I hit the glue with the soldering iron tip and a whiff of smoke from it went up my nostrils. I have a high pain threshold, but it was brutal. Now I only use Super glue far from solder connections.
You certainly can do so. I use them too but wanted to experiment with incorporating it into a smaller SMA package. As an aside, when you use a BNC tee (or any external adapter), you are adding a stub to the signal. You will see the impact of the stub at frequencies greater than 1 GHz which is certainly beyond the reach of my o-scopes.
I needed a custom adaptor to get from "Reverse SMB" plug to SMA receptacle. Well, reverse SMB doesn't exist except as a custom connector on this piece of military equipment. I used an SMB plug and a receptacle and swapped the center pins out, and then soldered it to the SMA connector, similar to what you did.
Why did you cut the legs on one of the SMA connectors? Wouldn't you then change the characteristic impedance of the connector, since they are designed for 50 Ohm? In this line of thought, isn't it better to just put the pins of the two SMA connectors against each other and solder where they touch? On the other hand, the legs don't provide sufficient shielding as the brass jacket and the dielectric do, therefore keeping the legs short might be better. What do you think?
You have a very good question. Look at the video starting at 4:00. Here you can see the device impedance is flat from 1 MHz to 30 Mhz. It's 49 Ohms and with basically no significant reactance indicated on the VNA. So, shortening the length of the connectors does not affect the test results in any negative way. What does improve shortening the distance is a better response from 30 MHz to 650 Mhz. After 650 MHz the return loss goes off the rails as shown below. The terminator is good to 650 Mhz. These measurements were the worst case at 650 Mhz. Return Loss: -20.6 dB SWR: 1.206 Z = 44.6 ohms -j7.1 S21 Insertion Loss: -3.93 dB
it would be interesting to test it to a higher frequency, and see what frequency it's good to - it might be surprising how good it is! The quality of the SMA connectors themselves might be a bigger issue than the construction of the through terminator, depending on how good those connectors are.
You make a good point Gorak. I retested it through 300 Mhz and results were very good. I tried to go beyond 300 mhz but my NanoVNA has an issue that will not allow for this. You can see what happens when I tried to do so in my next video. I think its defective.
@@rfburns3472 I tried to leave a comment on that video too, but youtube deleted it. You need to verify that the firmware you loaded is right for the H4, and that you have a real H4 and not a clone. Because it works at some frequencies and goes haywire afterwards points to a hardware incompatibility with the firmware. OR it really is defective. It's too bad you didn't try a full span it's capable of sweep before you upgraded the firmware. That would've been very helpful in figuring out if it's a firmware or hardware problem
Good advice. I went to nanovna.com which recomended AliExpress and the Zeenko store which I purchsed it from. I trust its not a clone. www.aliexpress.us/item/3256801087059810.html?spm=a2g0o.order_list.order_list_main.57.7e5f1802vGTljd&gatewayAdapt=glo2usa As for the H4 firmware, I did get the lastest file from Github......NanoVNA.H4.v1.2.20.dfu And, you are so correct that I should have tested it through its full frequency range when I first got it. Thanks for helping!
@@rfburns3472 If it's a true H4, you can also try the dislord firmware - if you see the same problem there, I'd say it's faulty and should be exchanged for a functional one!
The center pins were cut down to a stub. The 4 mounting posts were cut down so they do not interfer or touch the toroid. I used an epoxy glue to hold the connector in place.
Nice project with the ferrite setup. I put Super glue on a component on a PCB then soldered the component connection. I hit the glue with the soldering iron tip and a whiff of smoke from it went up my nostrils. I have a high pain threshold, but it was brutal. Now I only use Super glue far from solder connections.
Thanks for sharing your experience John. SG is nasty stuff to inhale or get fumes into your eyes.
Only a fly spec of the glue is needed.
You can use a T and a 50 termination to save the trouble of soldering the tiny parts.
You certainly can do so. I use them too but wanted to experiment with incorporating it into a smaller SMA package. As an aside, when you use a BNC tee (or any external adapter), you are adding a stub to the signal. You will see the impact of the stub at frequencies greater than 1 GHz which is certainly beyond the reach of my o-scopes.
I needed a custom adaptor to get from "Reverse SMB" plug to SMA receptacle. Well, reverse SMB doesn't exist except as a custom connector on this piece of military equipment. I used an SMB plug and a receptacle and swapped the center pins out, and then soldered it to the SMA connector, similar to what you did.
That was clever Brian. Thanks for sharing!
Why did you cut the legs on one of the SMA connectors? Wouldn't you then change the characteristic impedance of the connector, since they are designed for 50 Ohm? In this line of thought, isn't it better to just put the pins of the two SMA connectors against each other and solder where they touch? On the other hand, the legs don't provide sufficient shielding as the brass jacket and the dielectric do, therefore keeping the legs short might be better. What do you think?
You have a very good question. Look at the video starting at 4:00. Here you can see the device impedance is flat from 1 MHz to 30 Mhz. It's 49 Ohms and with basically no significant reactance indicated on the VNA. So, shortening the length of the connectors does not affect the test results in any negative way. What does improve shortening the distance is a better response from 30 MHz to 650 Mhz. After 650 MHz the return loss goes off the rails as shown below.
The terminator is good to 650 Mhz.
These measurements were the worst case at 650 Mhz.
Return Loss: -20.6 dB
SWR: 1.206
Z = 44.6 ohms -j7.1
S21 Insertion Loss: -3.93 dB
it would be interesting to test it to a higher frequency, and see what frequency it's good to - it might be surprising how good it is! The quality of the SMA connectors themselves might be a bigger issue than the construction of the through terminator, depending on how good those connectors are.
You make a good point Gorak. I retested it through 300 Mhz and results were very good. I tried to go beyond 300 mhz but my NanoVNA has an issue that will not allow for this. You can see what happens when I tried to do so in my next video. I think its defective.
@@rfburns3472 I tried to leave a comment on that video too, but youtube deleted it. You need to verify that the firmware you loaded is right for the H4, and that you have a real H4 and not a clone. Because it works at some frequencies and goes haywire afterwards points to a hardware incompatibility with the firmware. OR it really is defective. It's too bad you didn't try a full span it's capable of sweep before you upgraded the firmware. That would've been very helpful in figuring out if it's a firmware or hardware problem
Good advice. I went to nanovna.com which recomended AliExpress and the Zeenko store which I purchsed it from. I trust its not a clone. www.aliexpress.us/item/3256801087059810.html?spm=a2g0o.order_list.order_list_main.57.7e5f1802vGTljd&gatewayAdapt=glo2usa
As for the H4 firmware, I did get the lastest file from Github......NanoVNA.H4.v1.2.20.dfu
And, you are so correct that I should have tested it through its full frequency range when I first got it. Thanks for helping!
@@rfburns3472 If it's a true H4, you can also try the dislord firmware - if you see the same problem there, I'd say it's faulty and should be exchanged for a functional one!
How did you get the center pins to connect?
Did you bend them or cut them down?
The center pins were cut down to a stub. The 4 mounting posts were cut down so they do not interfer or touch the toroid. I used an epoxy glue to hold the connector in place.
What are the ferrite devices with SMA connector?
I got them from DigiKey. Here is the link.
www.digikey.com/en/products/detail/fair-rite-products-corp/0444164181/8594097
I just subscribe you after 1 min of watching the video . Looking forward to check rest of videos. 👍
You made my day! Thanks for subscribing. New video coming up soon, "DIY SMA RF Attenuators".