Thank you sir for another excellent educational video. If I remember correctly it's 3 to 5 inch pounds for soft brass SMA's but stainless steel connectors has a higher rating. Many years ago I ordered my first SMA torque wrench. The first SMA I used it on it ruined the connector. Foolishly I didn't read the manual prior to using the tool and was not holding the wrench correctly. On top of that I learned that the torque wrench I had bought had the higher torque rating for steel connectors. Since that time I have torqued hundreds of brass SMA's using a proper 3 to 5 inch pound wrench, including the NanoVNA, without an issue.
The attached link shows some discrepancies. I typically suggest using the manufactures guidelines for torque and care. This removes all doubt. www.microwaves101.com/encyclopedias/connector-torque
in a previous life, I was a component specialist at Nortel Networks, and previous to that, at a startup that was bought out by Nortel. At the startup, we had a couple of systems that we had designed. One was MMDS. and the other was LMDS. MMDS was essentially a wireless version of cable television distribution. It worked at 2.2-2.3 GHz. We used SMA connectors for the interconnections between indoor equipment and N type for the outdoor. We were always careful to use SMA torque wrenches set to 8 in.-lbs. for that equipment. The LMDS equipment was data communications equipment at 24-39GHz. That equipment used K and V type connectors (looked like SMA connectors on the outside, but the mating surfaces were different, and had different dimenstons). One of the engineers was doing some work, and didn't get the results he wanted, and determined (don't ask me how he determined this) that the Network Analyzer cables weren't tight enough, and grabbed a regular wrench and just started twisting. This was a 50GHz Network Analyzer (with is accompanying phase corrected cables, all V type connectors). He basically fused the cables to the front to of the Network Analyzer. When I ended up calling HP to get the Network Analyzer repaired, HP said that the unit was un-repairable so that it could meet its specifications, and replaced it under warranty. We did have to buy new cables (at $5K), plus the flat rate cost for repair. HP said they would repair it and use it for a sales demo unit. I went to work at Nortel when the startup was bought out. I was working on the same LMDS equipment, but when that product line was discontinued, I went over to work on the (at the time, CDMA) cellular base stations. Those base stations had RF combiners with SMA connectors on them. Each base station had a number of those combiners, and I was the component specialist that was responsbile for the combiners. Anyway, in the outdoor base stations, everything was wired up, (including the RF cables), and all 3 units were bolted to a giant metal skid for transport. In the transport process, the RF cables were coming loose. So the mechanical engineering group, without asking, changed the torque spec from 8 in.-lbs. to 21 in.-lbs. This was enough to damage some of the combiners. They got sent back to the supplier, who then gets back to me, saying that they were NOT going to provide warranty coverage on the defective units that showed damage due to over-torquing, which was almost all of the units. I went down, and under no uncertain terms, told the mechanical engineering group to put the torque spec. to 8 in.-lbs. This was mostly internal to the factory, until I had the field performance group write up a technical bulletingto all customers in the field, which resulted in both a field recall & retrofit (because the SMA connector solder joints could no longer be considered reliable) and considerable backlash from the end customers. It must be understood that the backlash was from the same customers who were complaining about needing to torque down the SMA connectors on-site in the first place.
I like the way you modified your socket by removing the side so you can see how it sits on the connector and will allow you to use it with cabled connectors. That is a great idea! I can do that and use my click stop screw drivers for connectors. Your simple torque calibration rig is also a good idea. Thank you!
An excellent explanation of the correct way to use a torque wrench! (A must see for my shop techs) All my torque wrench's are Snap-on and they get calibrated yearly. The hand placement, and holding the handle with a lose grip is important for a click type to work correctly. Even putting a twist on the wrench and keep it from clicking at it's setting. Snap-on even puts hand placement arrows on the handle to show just where the palm of you hand should lay. For in-pounds I always just use a finger loosely curled around the handle and slowly apply pressure till it click, pulling quickly will cause the wrench to miss-click giving a bad torque.
You bring up a good point. I would hope that people understood that the successive fast readings are NEVER actually something you would do. As you stated, you should always slowly apply pressure till it clicks.
very interesting because i got mine from wera. however they only sell torque drivers below a certain size (2.5nm). and with a driver you are gripping a rotating shaft so it the does not matter. so this is why they make them like that! (at least wera company)... problem is: that then makes them unsuitable for working on things like these sma connectors. unless they can be adapter with some little crow foot type thingy maybe? hmm i wonder. please let me know if happen to know abiout that. many thanks
oh i see now in the middle of your video here... i could in fact use the same crows foot you have there. but where to get these things so small. most of the crows feet i see online are for the larger size wrenches or i could make a copy of the special tool that you yourself made. but it really depends how difficult it is to make those things... it seems like you cut up a 6 sided deep socket, and removed 2 adjacent faces to create a gap in the side of the socket. is it ?
@@dreamcat4 That crows foot was custom made but you could purchase a 1/4" drive and get a hex to 1/4" if that is what you are after. I have found it much more useful than the split socket for tight spaces as normally in those cases I am working with semi-ridged.
@@joesmith-je3tq yes i do already have these 1/4 inch drive wera torque drivers. so do need a correctly sized crows foot to get access. to come in from the side next to the SMA, since the coax cable stick out axially out of the SMA and along the same axis we want to be torquing. so perhaps it's a shame if we cannot find these crows feet in the smaller sizes. have not bothered searching myself yet. it sounds here like you are saying that the crows foot must be 1/4" size spanner to fit the size of a standard SMA. sorry to ask for clarification but i live in europe here. and we tend to metric instead. like 4mm, 5.5mm, 7mm etc. i also wonder if these SMA type connectors also come in a few other different sizes. not too familiar myself anyhow the point is kindda moot (for me) if they cannot be found available anywhere. as unfortunately i don't have access to cnc machine to have cut my own crows feet. however! for other people here, those who happen to live in USA... then maybe an online CNC shop like send cut send might be a good service to use. For making your own crows feet. maybe also a few other useful little tools. honestly i wish i was more ingenious to think of these things like you there joe! very clever to think of accessories like these. so useful
and here I've just been finger tightening my sma connectors since I got a rtl-sdr. no wonder the connections keep loosening up if I so much as touch them.
just wondering what make and brand your tiny wrenches are! the ordinary ones. cannot find a good set anywhere! really enjoyed the video thanks BTW hope you will still be getting the new brymen to review. its great that they send them out to you for you channel. looking forwards to it!
The one shown was made by Dunlap. I also have a few from Craftsman and Easco as well. All made in the USA. I would imagine you could buy a used set or with the small amount of torque we are talking about maybe find a new cheap set.
@@joesmith-je3tq ah no worry i found some others now! actually the problem i find with mini spanners is that they often have very poor tolerances and fit relative to the smaller nut size. however the cheap price gives me an idea. perhaps i could buy a cheap set and then cut off the business end. and file a 1/4" sized notch into the stub. that would then turn it into a crows foot. with the few basic hand tools i have available to me here. it might just work!
ok furthermore: Proxxon 2021 English industrial catalog page 28+, goes down to 5.5mm (when sold individually). They have a low cost, but a high review rating on amazon. Facom have 440 series wrenches. Which go as low as 4mm (when sold individually). On page 219 of their catalog. Also high customer rating on amazon. Yet a bit cheaper than gedore or stahwille. But how about a ratcheting micro spanners. The smallest seem to be the: "KS Tools 503.42055". As tiny as it is. But no direction change lever. For that extra luxury, the Facom starts at 6mm (on page 203 of their catalog). And Proxxon starts at 8mm (page 25). With the facom Cow's foot (wrench size 7mm+ or 1/4"+) being on page 404
@@dreamcat4 I always tighten RF connectors by hand, then torque them. I see a few problems using a ratcheting wrench as you show. I would loose the feel of the connectors as they mate. The wrench is not open so no way to remove it when torquing coax. There may not be enough friction to allow the ratchet to function so you may need to add drag with your fingers.
@@joesmith-je3tq thanks joe, dont worry i am aware of those problems. was just speaking more generally there about mini wrenches for a more broad set of applications where the ratcheting feature can sometimes be useful. For this specific SMA application it really would be cutting the head off a double ended spanner (eg 6+7m), to fashion from those pieces a pair of the crows feet in 2 adjacent sizes. Such open double ended (of 2 sizes in 1 spanner) are sold by the likes of hazet, famco and stahwille. Different spanner series in their cataloges. Which forgot to mention here specifically. Was just so excited to find ratcheting versions so tiny! In fact stahwille and 1 other (maybe hazet) go as small as 3.2mm in a special range, they call them 'electrical' spanner. Which is even smaller than the previously stated 4mm. Which is pretty awesome. Expensive but awesome.
how about putting a mark on the fittings with a felt tip pen when they are in place once and either using that to decide when to stop tightening on subsequent occasions or checking your torque wrenching is correct (which I imagine it will be).
i think it's really helpful for me and i will recommend this video to my friends.and have you noticed elecbee connectors from China? it's more cheaper.thanks!
Maybe from Amazon: www.amazon.com/CDI-user-set-inch-Torque-screwdriver-range/dp/B00461ATRS/ref=sr_1_3?crid=2714RRGA9C5AY&keywords=cdi%2Btorque%2Bscrewdriver&qid=1647356797&sprefix=CDI%2Bt%2Caps%2C90&sr=8-3&th=1
I have seen a lot of videos on using the NanoVNA for ham radio. One thing that NONE of them seem to mention is that you need a SNA to S0-239 adapter to connect it to your antenna. Its like the poster just expect the viewer to MAGICALLY connect the NanoVNA to the antenna.
@@joesmith-je3tq For ham radio work, I use my VNA's thru connection all the time for building filters, BALUNS, measuring attenuation and insertion loss. Also, for Smith chart, measuring phase, feed line length etc. But yeah, a nanoVNA is a convenient alternative to spending a $grand on a bespoke antenna analyzer that can do HF to 1.2 GHz
If you only screw your SMA connectors hand tight, you will inevitably get grossly incorrect and inconsistent results! So, it is necessary to used a wrench to tighten SMA connectors. How tight? 5 or 6 in-lbs. is good for electrical connection, 8 in-lbs. for permanent vibration proof connection. Right now you can buy a bend-over type torque wrench on Amazon for only $31. IMPORTANT - the wrench comes without lubrication! You must apply oil to the elbow and internal cylindrical sliding surfaces, and grease to the ball surface - else excess friction will probably break your SMA connector! Once the tool is properly lubricated, it should be calibrated using known weight and length scales. With all this done, an SMA connector can easily take 6 to 8 in-lbs. torque - no problem! Do not push on the end of the torque wrench handle! When applying torque, remember that you are literally "applying torque" - not linear force. This means your hand and wrist should impart a twisting action. If there is any linear force applied to the tool, it will result in a combined force (sheer + bending + torsion) when all that is needed is a simple torsional force. Unnecessary combined force could break or damage the delicate SMA connectors or PC board. --a mechanical engineer
Thank you sir for another excellent educational video. If I remember correctly it's 3 to 5 inch pounds for soft brass SMA's but stainless steel connectors has a higher rating. Many years ago I ordered my first SMA torque wrench. The first SMA I used it on it ruined the connector. Foolishly I didn't read the manual prior to using the tool and was not holding the wrench correctly. On top of that I learned that the torque wrench I had bought had the higher torque rating for steel connectors. Since that time I have torqued hundreds of brass SMA's using a proper 3 to 5 inch pound wrench, including the NanoVNA, without an issue.
The attached link shows some discrepancies. I typically suggest using the manufactures guidelines for torque and care. This removes all doubt.
www.microwaves101.com/encyclopedias/connector-torque
in a previous life, I was a component specialist at Nortel Networks, and previous to that, at a startup that was bought out by Nortel.
At the startup, we had a couple of systems that we had designed. One was MMDS. and the other was LMDS. MMDS was essentially a wireless version of cable television distribution. It worked at 2.2-2.3 GHz. We used SMA connectors for the interconnections between indoor equipment and N type for the outdoor. We were always careful to use SMA torque wrenches set to 8 in.-lbs. for that equipment. The LMDS equipment was data communications equipment at 24-39GHz. That equipment used K and V type connectors (looked like SMA connectors on the outside, but the mating surfaces were different, and had different dimenstons). One of the engineers was doing some work, and didn't get the results he wanted, and determined (don't ask me how he determined this) that the Network Analyzer cables weren't tight enough, and grabbed a regular wrench and just started twisting. This was a 50GHz Network Analyzer (with is accompanying phase corrected cables, all V type connectors). He basically fused the cables to the front to of the Network Analyzer. When I ended up calling HP to get the Network Analyzer repaired, HP said that the unit was un-repairable so that it could meet its specifications, and replaced it under warranty. We did have to buy new cables (at $5K), plus the flat rate cost for repair. HP said they would repair it and use it for a sales demo unit.
I went to work at Nortel when the startup was bought out. I was working on the same LMDS equipment, but when that product line was discontinued, I went over to work on the (at the time, CDMA) cellular base stations. Those base stations had RF combiners with SMA connectors on them. Each base station had a number of those combiners, and I was the component specialist that was responsbile for the combiners. Anyway, in the outdoor base stations, everything was wired up, (including the RF cables), and all 3 units were bolted to a giant metal skid for transport. In the transport process, the RF cables were coming loose. So the mechanical engineering group, without asking, changed the torque spec from 8 in.-lbs. to 21 in.-lbs. This was enough to damage some of the combiners. They got sent back to the supplier, who then gets back to me, saying that they were NOT going to provide warranty coverage on the defective units that showed damage due to over-torquing, which was almost all of the units. I went down, and under no uncertain terms, told the mechanical engineering group to put the torque spec. to 8 in.-lbs. This was mostly internal to the factory, until I had the field performance group write up a technical bulletingto all customers in the field, which resulted in both a field recall & retrofit (because the SMA connector solder joints could no longer be considered reliable) and considerable backlash from the end customers. It must be understood that the backlash was from the same customers who were complaining about needing to torque down the SMA connectors on-site in the first place.
I loved this. Destructive testing examples are always the most educating.
George, I don't know how else to convey what it takes to pull one off a board. That's a lot of torque.
I like the way you modified your socket by removing the side so you can see how it sits on the connector and will allow you to use it with cabled connectors. That is a great idea! I can do that and use my click stop screw drivers for connectors.
Your simple torque calibration rig is also a good idea.
Thank you!
An excellent explanation of the correct way to use a torque wrench! (A must see for my shop techs) All my torque wrench's are Snap-on and they get calibrated yearly. The hand placement, and holding the handle with a lose grip is important for a click type to work correctly. Even putting a twist on the wrench and keep it from clicking at it's setting. Snap-on even puts hand placement arrows on the handle to show just where the palm of you hand should lay. For in-pounds I always just use a finger loosely curled around the handle and slowly apply pressure till it click, pulling quickly will cause the wrench to miss-click giving a bad torque.
You bring up a good point. I would hope that people understood that the successive fast readings are NEVER actually something you would do. As you stated, you should always slowly apply pressure till it clicks.
very interesting because i got mine from wera. however they only sell torque drivers below a certain size (2.5nm). and with a driver you are gripping a rotating shaft so it the does not matter. so this is why they make them like that! (at least wera company)... problem is: that then makes them unsuitable for working on things like these sma connectors. unless they can be adapter with some little crow foot type thingy maybe? hmm i wonder. please let me know if happen to know abiout that. many thanks
oh i see now in the middle of your video here... i could in fact use the same crows foot you have there. but where to get these things so small. most of the crows feet i see online are for the larger size wrenches
or i could make a copy of the special tool that you yourself made. but it really depends how difficult it is to make those things... it seems like you cut up a 6 sided deep socket, and removed 2 adjacent faces to create a gap in the side of the socket. is it ?
@@dreamcat4 That crows foot was custom made but you could purchase a 1/4" drive and get a hex to 1/4" if that is what you are after. I have found it much more useful than the split socket for tight spaces as normally in those cases I am working with semi-ridged.
@@joesmith-je3tq yes i do already have these 1/4 inch drive wera torque drivers. so do need a correctly sized crows foot to get access. to come in from the side next to the SMA, since the coax cable stick out axially out of the SMA and along the same axis we want to be torquing.
so perhaps it's a shame if we cannot find these crows feet in the smaller sizes. have not bothered searching myself yet. it sounds here like you are saying that the crows foot must be 1/4" size spanner to fit the size of a standard SMA. sorry to ask for clarification but i live in europe here. and we tend to metric instead. like 4mm, 5.5mm, 7mm etc. i also wonder if these SMA type connectors also come in a few other different sizes. not too familiar myself
anyhow the point is kindda moot (for me) if they cannot be found available anywhere. as unfortunately i don't have access to cnc machine to have cut my own crows feet. however! for other people here, those who happen to live in USA... then maybe an online CNC shop like send cut send might be a good service to use. For making your own crows feet. maybe also a few other useful little tools. honestly i wish i was more ingenious to think of these things like you there joe! very clever to think of accessories like these. so useful
Great and informative test!
Thanks for sharing your experience with all of us 👍😊
Thanks, Joe. Very informative.
Thank you Sir!
and here I've just been finger tightening my sma connectors since I got a rtl-sdr. no wonder the connections keep loosening up if I so much as touch them.
just wondering what make and brand your tiny wrenches are! the ordinary ones. cannot find a good set anywhere! really enjoyed the video thanks
BTW hope you will still be getting the new brymen to review. its great that they send them out to you for you channel. looking forwards to it!
The one shown was made by Dunlap. I also have a few from Craftsman and Easco as well. All made in the USA. I would imagine you could buy a used set or with the small amount of torque we are talking about maybe find a new cheap set.
@@joesmith-je3tq ah no worry i found some others now! actually the problem i find with mini spanners is that they often have very poor tolerances and fit relative to the smaller nut size. however the cheap price gives me an idea.
perhaps i could buy a cheap set and then cut off the business end. and file a 1/4" sized notch into the stub. that would then turn it into a crows foot. with the few basic hand tools i have available to me here. it might just work!
ok furthermore: Proxxon 2021 English industrial catalog page 28+, goes down to 5.5mm (when sold individually). They have a low cost, but a high review rating on amazon.
Facom have 440 series wrenches. Which go as low as 4mm (when sold individually). On page 219 of their catalog. Also high customer rating on amazon. Yet a bit cheaper than gedore or stahwille.
But how about a ratcheting micro spanners. The smallest seem to be the: "KS Tools 503.42055". As tiny as it is. But no direction change lever. For that extra luxury, the Facom starts at 6mm (on page 203 of their catalog). And Proxxon starts at 8mm (page 25).
With the facom Cow's foot (wrench size 7mm+ or 1/4"+) being on page 404
@@dreamcat4 I always tighten RF connectors by hand, then torque them. I see a few problems using a ratcheting wrench as you show. I would loose the feel of the connectors as they mate. The wrench is not open so no way to remove it when torquing coax. There may not be enough friction to allow the ratchet to function so you may need to add drag with your fingers.
@@joesmith-je3tq thanks joe, dont worry i am aware of those problems. was just speaking more generally there about mini wrenches for a more broad set of applications where the ratcheting feature can sometimes be useful.
For this specific SMA application it really would be cutting the head off a double ended spanner (eg 6+7m), to fashion from those pieces a pair of the crows feet in 2 adjacent sizes. Such open double ended (of 2 sizes in 1 spanner) are sold by the likes of hazet, famco and stahwille. Different spanner series in their cataloges. Which forgot to mention here specifically. Was just so excited to find ratcheting versions so tiny!
In fact stahwille and 1 other (maybe hazet) go as small as 3.2mm in a special range, they call them 'electrical' spanner. Which is even smaller than the previously stated 4mm. Which is pretty awesome. Expensive but awesome.
how about putting a mark on the fittings with a felt tip pen when they are in place once and either using that to decide when to stop tightening on subsequent occasions or checking your torque wrenching is correct (which I imagine it will be).
Torque is not the same as position.
i think it's really helpful for me and i will recommend this video to my friends.and have you noticed elecbee connectors from China? it's more cheaper.thanks!
hello, can you share the purchase address of the product at 4:05?
Maybe from Amazon:
www.amazon.com/CDI-user-set-inch-Torque-screwdriver-range/dp/B00461ATRS/ref=sr_1_3?crid=2714RRGA9C5AY&keywords=cdi%2Btorque%2Bscrewdriver&qid=1647356797&sprefix=CDI%2Bt%2Caps%2C90&sr=8-3&th=1
I have seen a lot of videos on using the NanoVNA for ham radio. One thing that NONE of them seem to mention is that you need a SNA to S0-239 adapter to connect it to your antenna. Its like the poster just expect the viewer to MAGICALLY connect the NanoVNA to the antenna.
I've have no interest in ham radio. It's like hams just expect the only use of a VNA is an antenna analyzer.
@@joesmith-je3tq For ham radio work, I use my VNA's thru connection all the time for building filters, BALUNS, measuring attenuation and insertion loss. Also, for Smith chart, measuring phase, feed line length etc. But yeah, a nanoVNA is a convenient alternative to spending a $grand on a bespoke antenna analyzer that can do HF to 1.2 GHz
@@reedreamer9518 Rare
If you only screw your SMA connectors hand tight, you will inevitably get grossly incorrect and inconsistent results! So, it is necessary to used a wrench to tighten SMA connectors. How tight? 5 or 6 in-lbs. is good for electrical connection, 8 in-lbs. for permanent vibration proof connection.
Right now you can buy a bend-over type torque wrench on Amazon for only $31. IMPORTANT - the wrench comes without lubrication! You must apply oil to the elbow and internal cylindrical sliding surfaces, and grease to the ball surface - else excess friction will probably break your SMA connector! Once the tool is properly lubricated, it should be calibrated using known weight and length scales. With all this done, an SMA connector can easily take 6 to 8 in-lbs. torque - no problem!
Do not push on the end of the torque wrench handle! When applying torque, remember that you are literally "applying torque" - not linear force. This means your hand and wrist should impart a twisting action. If there is any linear force applied to the tool, it will result in a combined force (sheer + bending + torsion) when all that is needed is a simple torsional force. Unnecessary combined force could break or damage the delicate SMA connectors or PC board.
--a mechanical engineer