Ham Radio Basics--Coax Connector Loss---A Surprise

How much loss is there in coax connectors?

[@jw6953]

Hello , my dad was a amateur radio operator , his father was a radio man in World War II at D-Day. I grew up in a house with November 3 Hotel whiskey blasting through the TV and stereo... we always knew when it was a radio contest weekend in Morse code or in voice. I started to study for the test after my dad passed away I stopped. I would like to continue studying for the test and it starts with the basics. Thank you for the video it is helpful. Thank you

[@ham-radio]

Go for it James! 73, Jim

[@markbruechert9967]

Thanks for a very easily-understood test, Jim. Cheers Mark VK3PDG Australia

[@temmert8391]

do you think that if he traveled up to 10M he would see more of a loss?

[@michaeljorcutt3142]

I enjoy watching your videos. The Microphone demonstration was really good. Eventually will watch them all. Thanks. Not too far from you in Placer County. Michael

[@rrrandommman]

I like the zoomed out look, I get to see all your fascinating gear while you explain things. 73.

[@revoxjazz8317]

Jim: Thanks for the simple explanations, for the calm way they are made, and for what you have technically suggested, directly or indirectly. So it's worth spending a few minutes on KZbin. Macedo Pinto, from Portugal. 73

[@garyrobinson8991]

Wow....interesting to find someone my own age with such a vast knowledge of Ham technical info. I’m just returning to the hobby that’s been paused for over 40 years. Hope to invest lots of time getting back up to speed now that I’m retired..... enjoying your videos !!

[@DigiSage]

W6L6, just writing in to say that I love all of your videos and I hope you keep making them. The way you speak and explain things is very understandable and pleasant to follow.

[@ham-radio]

Thanks Dan!!!!!!!! 73, Jim W6LG

[@DigiSage]

Woops forgot my call sign! 73, Dan KB2USN

[@dougm8882]

Thanks, great video. You touched on the fact that at VHF/UHF frequencies, losses would be higher, and was hoping that you would have tested/verified that as well (maybe in another video?). 2m is popular, especially for emcomm, which I do (and sometimes 70cm), and so I am very interested to know what the losses would be at those frequencies. Not necessarily for a stack of connectors, but for say 3 or 4 including a couple short (12") jumpers. Thank you.

[@MrSundownman49]

Hello Jim,Very nice explanation and Tutorial,I very much enjoyed this. I have repaired Electronics Professionally for more than 45 years and I have had many discussions with others about Coax Connector losses being negligible and proved it to a few also before KZbin,but you nailed it so even the Naysayers can not dispute this any longer,I have subscribed and I am saving your link for the next Naysayer!! You and I are the same age,I was born April 25,1949 a Very good year!! I am a retired US Marine,Vietnam War Combat Veteran and retired CET living in the Philippines and Licensed here as a Class B General DV7NIB I am good on QRZ.73 Bob

[@ham-radio]

Hi Bob, Thank you for all in your message. Thank you for you service to the US. Yes we are just a month apart for our DOB. I had a massive PE and that has caused many problems. Also now I haev severe osteoporosis equal to a 90+ year old person. At this time I am wearing a monitor for 30 days. The electrodes have caused rashes. I am going to do that connector test again using many SMA connectors. I will use a NanoVNA. I think that 2 to 3 feet of connectors will have almost no loss at HF and some significant loss at UHF. At HF frequencies that group of connectors is just a small fraction of the wave. At UHF it may be longer than the wavelength and really mess with the shape of the wave causing losses. Thanks for your information and support. If you have some ideas about a future video from me, please let me know. I was first licensed in 1963 (I think that was the year). I have been off the air for a year and hope to get back on the air in a few days. Thia is the longest I have not been able to be QRV. One of my new neighbors is a ham and his wife was very active before they were married. She also has a DU callsign. I believe that activity there is high/good. Keep in touch Bob and again thanks for your support. Great to me you. 73 from Rocklin CA, Jim W6LG

[@g0fvt]

An excellent "myth busting" video, thank you for making and uploading.

[@ham-radio]

I like that "myth busting!" 73, Jim

[@g0fvt]

Jim, even in the trade there are people that are convinced that connector losses are up to about 0.5dB EACH. (Usually VHF/UHF) with 100w fed into a long chain of them the connectors would heat rapidly if their theories were true. It has been many years since I felt inclined to assemble a long string of adaptors in order to prove the point. Well done for taking the time to do this.

[@bobwilson2470]

Thanks for making this! I have sent a note about it to our ham club (Four Lakes Amateur Radio Club). I plan also to mention your projected series of shows to our upcoming technician and general license classes. There may be a few things in this show that those coming to a technician class won't automatically understand, but that's OK, they need to learn to ask questions too!

[@ham-radio]

+Bob Wilson Wow, thank you Bob. That is so great. I am trying to keep it simple. I just finished one about microphones and have decided to do it over. I got into kind of rant about the ESSB guys. When I rerecord the video I will stick to the basics like ALC, compression and mic gain setting. Thanks again!

[@ElPasoTubeAmps]

Jim, I so agree with you and appreciate your time and effort in making this video. I hope what others may take away from this presentation is that the losses at HF in coax (and multiple connectors) is of no concern. If you don't have an obvious anomaly in your transmission line, the good coax of today (and yesteryear) is for all practical purposes, "lossless" at HF for hundreds of feet. Now, to contrast this to an extreme - when I worked for Lockheed as WSMR in the 1990's, I did 11 GHz work and had the best of the best equipment straight from the cal lab of WSMR to measure these antenna systems. As the coax came down from the parabolic dishes, it would be terminated in an N connector, then a barrel then another N connector to make a physical transition. This may seem silly but even the very best 90 degree elbows would loose 100% of the signal from the input of the 90 degree elbow to the output of the elbow. Seems weird but it is true so, gradual physical bends, even with the measurable loss of every N connector was necessary to get the signal from the antenna to the equipment. An extreme case for the ham radio operator for sure. Now on to the WiFi band of today at 2.4 GHz - certainly not so extreme as 11 GHz but I have demonstrated that all of the gain obtained in an antenna can be lost in just inches of transmission line at 2..4 GHz or poor connectors. For HF work the PL-259/SO-239 is a good choice. N connectors are not necessary. Great video, Jim. Thanks for posting.

[@noth606]

ElPaso TubeAmps As per my understanding your statement is simply incorrect, and that's based on coax manufacturers own numbers and independent testing. Losses in coax runs of 100ft are significant and vary by type, brand and frequency significantly also, if they didn't coax makers wouldn't need to make a lot of different types of it with different diameter, materials etc. To pick an example, if I have a Dutch N class license my max transmit is 25w which means I'm likely to spec my transceiver per that TX output, if I run 100ft of the wrong type of coax to my antenna, at the end of that cable I will have less than 20w output, more like 18-19w. That IS significant.

[@elmakednos]

Very interesting video. Thank you for the test. It was and always be usefull.

[@tashpaug]

Great Video Jim. I really enjoyed getting that answered. 73

[@bstrickler]

That makes me happy. I was trying to figure out how I was going to keep losses to a minimum for my system, because I'd be running 100ish feet of LMR600 to my house, but I'd have to do a 90° turn through a junction box. I'm perfectly comfortable using a few 90° connectors on my system now.

[@markwilliams8702]

Thanks Jim. Concerned with my coax connector for my T2L T for 10 and 11 meters. You have just answered my question. CT9484

[@ham-radio]

Okay, that's good Mark. Thanks & 73 Jim W6LG

[@marklowe7431]

Some of these myths remain dis education until someone decides to challenge an correct it. Today's the day. This video really dusted out the b/s. Excellent.

[@samiam5557]

Great video, looking forward to more!

[@Nico_83]

great video Jim, keep 'em coming ! I did a similar connector test a while ago. Greetings from Germany.

[@samiam5557]

A video showing your progress restoring equipment would be great, I enjoy those and find them helpful.

[@jimshirey7344]

Great presentation easy to follow.Will be sharing with others

[@DENMONKEY]

Thanks Jim, I'd never understood they theory of loss through connectors and It has never sat well with me. If anything I'd expect them to be more robust electrically and mechanically than the coax itself. If that makes sense :) I guess that's what prompts us into action to test such things. Whilst I love seeing new hams come on board, sometimes it seems theyre more prone to asking a single question multiple times to get the answer they are after. it would be great if they just took the time to experiment and find out for themselves.Of course share their story when theyre done. Thanks for showing us and sharing the joy that can be had from not taking anything for granted and finding out for yourself. regards Brett VK2MRX

[@ham-radio]

Thanks Brett! I think you are correct about the connectors. Here's my theory that is unsupported. The reason that the string of connectors showed no loss is that the length of a connector (or connectors) was/is relatively short compared to the wavelength. In other words, if I had a wavelength long string of connectors the loss would have been much greater than coax. Given that a connector is very short compared to the wavelength and it was a short length I was testing, the loss is undetectable. If the typical ham station has a dozen connectors, for example, that length of connectors is a fraction of a wavelength and therefore have a fraction of loss. Okay, I can't prove my theory but it makes some sense. Thanks Brett and 73, Jim Heath W6LG

[@mbarreto64]

Jim, just discovered your videos few days ago and immediately subscribed the channel because I really like most of your videos. Relative to the connectors loss, I was impressed with the result. There is one thing that was interesting to be tested, that is the solderings on the connectors. You tested the connectors daisy chain attached, but only the extremity connectors have cable. It could be interesting to know how much loss does the solderings in the connectors add (if any notoceable). 73, CT1EFT

[@OutdoorsOnTheAir]

Hello Jim, thank you very much for this. I just posted a KZbin video on my Field Day 2016 effort and at one point mentioned I was using a patchwork of short cables to make the run to the antenna rather than one long length. I presumed there would be loss due to the connectors but you have just taught this old dog a new trick. I'm now a subscriber to your channel. 73 from Tracy VE3TWM.

[@ham-radio]

Thanks Tracy. If you have an idea for a basic ham radio video, please let me know. 73, Jim W6LG

[@user-vy7op5ux6n]

My Grand Parents lived in Bear River Pines for some time. My question on the connectors relates to issues that may occur over time with dissimilar metals on butt SO239 and 2 PL-239s. Your comment? Thank you

[@g3cwi_Radio_Adventures]

Great production values. I need to work far harder on my ham radio videos!

[@quicksilverradio2596]

Nicely done.

[@4000marcdman]

Would love to see the results on gmrs frequencies.

[@thenar]

Jim, I hope you’re feeling better.

[@DonHavjuan]

And at 2m? 70cm? I wish you'd tested those to compare. :(

[@robertdixon6536]

The proof is in the pudding! Thanks for the vid.

[@W8KZW]

Hi, Jim .... thanks for the video. Two questions .. 1) Wouldn't the loss of the connectors be more of a factor for received signals at say 20 uv? The ratio of the inserted impedance vs. pass through power would be significantly more noticeable? 2) I have previously understood that the most accurate meter readings occur near full scale, not mid-scale. For your experiment, a stated accuracy of + or - 5% of full scale deflection on the 250 watt slug is a 25 watt swing, or 25% at the 100 watt midscale point. 25 watts at the 250 watt point is a 10% margin of error.

[@Paddy_Roche]

Hi Jim, a quick thank you for these fantastic and educational videos that you make. I'm a year in to Amateur Radio currently studying for my intermediate level licence here in the UK. Yours videos are such a help with clear explanations. Best wishes to you Sir and thanks again. Paddy (M6VBO)

[@nvrumi]

I am an engineer. ;) [insert engineer joke here] Measurements are always preferred to opinion. Thank you.

[@eugenegannon8806]

you prolly dont give a shit but if you are stoned like me during the covid times you can stream pretty much all of the new series on InstaFlixxer. I've been binge watching with my gf for the last few weeks xD

[@axelcohen6685]

@Eugene Gannon yea, I have been watching on instaflixxer for years myself :D

[@4BoltClevo]

I had a resonant antenna once. When the wind blew hard it would hum like crazy!

[@ham-radio]

OK? 73 Jim

[@4BoltClevo]

I meant that it was resonant at RF AND audio. I had to provide extra bracing to stop the hum. After that it was great. Great channel BTW.

[@adambatchelder4121]

Great video, I'm in Grass Valley as well over by ceder ridge.

[@ham-radio]

I know you last name. Sadly, I had to move after being there for 38 years. I had to get into Kaiser and closer to my oldest son. 73 from Rocklin!

[@adambatchelder4121]

@@ham-radio sorry to hear that, I may have crossed paths with you at the local ham club meetings, I went to a few over the years.

[@Bernard-John]

great video,well explained,radio ham for dummies.

[@rickkephart5690]

I'm getting in this late, but thank you for making the video's.

[@JamesRWeber-ee1kr]

Jim do this with QRP 5 watts and 1 watt also please describe the cable you use RG213? Rg8x? also 2 meter 70cm as you mentioned it is VERY important to have good cable and connector especially when operating in QRP.

[@budchestnut9303]

Tnx for the video. Why not tell them what happens when you do the same test at a Gigahertz?

[@billvet6]

Very good. Look forward to more of your videos. Always wanting to learn more . Liked and subscribed. 73 de AB9QU

[@stevenlawhon3695]

Which is better UHF pl259 or N connector? HF only. 1.8-6m

[@ham-radio]

No question in my mind, the PL259. I have killed many N connectors with that small pin and small contact. I had them fail many times with QRO. 73, Jim

[@RickDean]

Great audio! What microphone / audio setup do you use? Rick

[@ham-radio]

Hi Rick, I think I was using a simple electret mic connected to my cellphone at that time. Thanks for asking. 73, Jim W6LG

[@DavidLopez-bz4rj]

Try this on VHF and UHF, Im sure youll be surprised, HF not signifficant losses over distance with good quality cable

[@ham-radio]

No, I won't be surprised. I have been doing this for 55 years now. The coax cable is the most important part of the station. Guys will buy a $300 microphone and then use RG8X. Thanks Dave. 73, Jim

[@DavidLopez-bz4rj]

@@ham-radio Im sure you are experienced enough. I enjoy your videos, keep making. I use 75ohm outdoor cable with crimped F connectors on it, waterproof and solid, on VHF. No impedance matching, short length to antenna, so I asume reasonable SWR. No difference with 50ohm, PL connectors, and RG213. I use a handheld radio connected to homemade 75ohm base yagi antenna, external microphone and speakers, and 5w of power.

[@billg2942]

Stringing the "tweenies" together is pretty much like inserting a chunk of quality hardline.

[@hman630]

Can you Please make a Video on how to ground a dipole antenna AND also how to ground the coax coming from the dipole antenna? I've read so many things about it that now I'm confused even more. TNX,

[@ham-radio]

I answered this early today. A dipole is not grounded. It is a balanced antenna. 73, Jim W6LG

[@richardvaughn2705]

hman630 You cant ground a balanced antenna directly, however if you feed the dipole with unbalanced feed line (coax) then you can ground the sheilding of the coax but you should use a 1:1 current balun to prevent the sheild of the coax from radiating and becoming part of your antenna which would ruin your swr. Any DC static or lightning strike would pass through the balun to your ground point at the bottom of the balun on the sheild of the coax ( basically wrap a wire around the connector and attach that to your mast or to a ground wire) and you can use a lightning arrestor to take care of the center conductor (which will have a ground screw attached to the sheilding). Loop antennas have an advantage in that both sides are at DC short so they are easier to ground (just a current balun and ground the coax sheild).

[@kenbarnes1830]

no surprise to me ive used pl259s at 145 mhz and 70cms NO PROBLEMS also 75 ohmo coax NO PROBLEMS about time some one BLEW the myth

[@ham-radio]

Thanks Ken. For an ancient connector, it works good. 73, Jim

[@steadfast666]

great test - thx - interresting result :-) 73 de HB3YVZ

[@duenge]

Before you start your experiment, this retired fireman predicts there will be a loss of 25 psi, or 50 gallons a minute....73.

[@ham-radio]

That is very funny! Thank you for being a fireman (fireperson?). I have sometimes volunteered with Cal Fire as a communications guy/ham radio. They are amazing soldiers who help so many folks everyday. That includes saving my butt two times from near fatal events. 73 and thanks for the funny comment. I laughed out loud.

[@santiago101100]

I know that this is HAM but maybe you guys know the results if I would of used this setup with a CB radio. I'm wondering if it would be the same results?

[@lt4324]

I know your post is old and you may have already found out your answer, BUT "YES" same results, actually SAME for the entire "HF spectrum". You can use as many as you need without any noticeable loss. Take it ez, 73 de KD6SBR

[@whip205inthebam3]

W6LG, you're only telling a one sided story here. You're trying to show there is no loss in the connectors on TX yet you're leaving RX out all together. Another thing you're showing is a whole bunch of connectors in a row which is not how they would normally be installed at most stations. The loss is rated in db not in watts as you seem to be trying to show using a dummy load. I do no below believe that manufacturers of these connectors would report a loss if there were none.

[@scott8049]

ugh. you seemed like a nice guy until you started slap jawing about guys microphone settings. Ham radio is not WCBS AM out 50K watts out of NYC.