How does my multiband antenna work with a random amount of coax (the distance from the radio to the antenna) and perfect SWR on bands from 80m to 6m? This is crazy. Why don't you just tune the antenna correctly? You are using 27Mhz - just tune the antenna. The coax is 50 ohms, the radio is 50 ohms - so make the antenna the correct size to correspond (PS it will never be perfect).
My antenna is perfect 1.1 at the antenna. Your multi band antenna. Is it random bands or is it specifically designed to be bands that are resonant with one another. So in two other videos of mine you watch me change nothing but the length of coax it doesn't even have an antenna it has a perfect match dummy load..... And yet the SWR, capacitance and reactance all changes depending on different lengths. Now let me ask u this. Do you or do you not own an antenna tuner? Regardless of it being external or built into the radio. It does what? It adds either inductance or capacitance to the antenna circuit to make it land on 50ohms right? Ok. Now. If you have a tube amplifier does it or does it not have an input tuning network along with an output tuning network? All my old ones do. Why? If the input tune of the amp represents the load/ antenna as far as your radio is concerned y not just have it at a set tune that is not adjustable? Everyone is going to be using 50 ohm coax between the radio and amp right. So y make it adjustable? It's so u can get the lowest SWR at your radio right? How about the output tuning network. Tune and load right? What is that doing? It's tuning the antenna network for the band you're on right? So yes when I'm running my tube amplifiers it really doesn't matter what length my coax is because the amp has input and output tuning networks to make it as close to 50 ohms as possible. Now come on over tho the CB world of transistor amplifiers..... Almost none of them have adjustable input and output tuning networks. So u can do one of two things. Open the amp and physically modify the input and output tune to match whatever random coax you are using from radio to amp and amp to antenna or the builder of the transistor amp makes every amp tuned for a null coax. I've done both. I build both transistor and tube amps for myself only. I have even added air variable capacitors to my base station transistor amps. But in mobile situations they won't survive and will get out of tune too often. So we build for null coax because that's the only thing I can make consistent. If you plug in an antenna analyzer and tune your antenna for the lowest possible SWR and it's still too high install a null coax to get it to 1.1 or better. When u install the transistor amp that is tuned for that 1.1 match it will be happy and have absolutely no reflect. DX commander I love your stuff. I'm very new to this hobby and you're a pro. I just think that sometimes we get stuck in our ways of it's always worked for me so therefore u must be wrong and it just takes a new set of eyes to ask questions and investigate issues that many people are having but many people just ignore. Yes 1.5 is good enough. But I have always been able to tune my network to 1.1 or better while pushing more power than I care to admit to. The lower the SWR the better your reception will be. That is usually more of a factor for me than loosing a few watts In reflect.
Exactly correct way my friend!!!! Making the coax to be invisible to the system… On my next video I will make a note and add this link to the description to show everyone how it is done correctly!!!!
I fucked off about 100’ of RG-213-U coax on a mobile trying to get rid of reflect. My MFJ was showing 4 with T and dummy load and I was cutting all my coax too short a couple of inches. I learned a very valuable lesson that week. Great video 👍
It would be interesting to compare the measurement on a hot and cold day. You will see a difference using the MFJ. It would be interesting to compare the MFJ measurement to a Rigexpert measurement.
I've not heard that but temperature variation is absolutely a real thing. I only have two cb radio set ups so probably won't be buying another antenna analyzer anytime soon
As you probably already know, there is another video out there that shows him cutting his coax an inch at a time to get the meter to read Zero. That just adds more confusion to the already confusing question of "how long should my coax jumper be from my amp"....
I am in the process of trying to find how to find a half wave piece of coax to rebuild my Circular polarized 2 meter satellite antenna. That’s how I found your video keep up the experimenting. I have a Rigol Spectrum analyzer and swr bridge. And I done it before just need something to jog my memory 73s from Kc8qdq
@@fredbrauer5429 old video I have a few but essentially I believe that's what I did in this video is cut the coax with dummy attached at desired frequency till coax had no influence on the tune
The electrical leght is the only thing to determine remove the dummy load and the coax to the meter your tuning the coax length with the dummy load you are balancing both to each other. The dummy load has a different reading than the amp obviously it adds to confuse the coax length if you have to use a dummy load put it on the opposite end of the coax did you ever think of checking the amp-. Using the right cap will allow the right reading
I kind of understand what your saying but in the video I do put the dummy at the end of the coax and it produces the same results. The reason I put it on a t at all is because when u are cutting it to tune it's length obviously there is no connector on the end yet. Also I'm not trying to tune the amp. It should already be tuned. I'm trying to add a cable that is essentially invisible to the equipment as to not change the equipment tune. If the equipment is out of tune than that should be tuned with caps and such by itself
I think you nailed it man. I want to cut one to tune my base antenna with. Its 50 feet now RG8X. It should 42.3ft by calculating at 27.205. Which Fatboy Amp do you have?
@@electromechanicalstuff2602 Wow! I have the Stryker 955 also and would like to have some more power. Do you know about how far the 8 Pill gets out at full power? How close does your coax length work out to calculated half wave length?
@@RC-Heli835 ended up buying a 2 pill fatboy 2879 driver for the Fatboy 8 pill. The Stryker is not enough to drive the 8 pill. Turn the gain way down on the 955. I still haven't put it all in the mobile yet. But with the IMAX 2000 and the rg213 I have ran to it on the base. My antenna is 40' in the air so the tip of the antenna is 64' tall I've talked 40+ miles.
For years and years, the big CB manufacturers have been selling plug and play mobile antennas. In the package is an 18' foot length of coax. Greater minds than ours came up with that formula, so who am I to argue. Ask in any CB forum what length a jumper should be and you will be met with a resounding '6 foot' or multiples thereof answer.
Many things work fine. I just wanted perfection. My SWR is 1.15 at the worst channel and 1.1 at the best channel. This coax tuning is what allowed that to happen. With no other changes I ran a generic coax that came on the A10 Stryker from factory and my SWR was 1.4 at it's worst and 1.25 at it's best. After I tuned the antenna using two different antenna analyzers that gave me the same results.
@@VicGreenBitcoin unlikely. Because the only thing I changed was the cable. From untuned to tuned. Using a smith chart you can see that inductance, reactance and capacitance will effect your overall tune. Technically it doesn't change your SWR but it will reflect a better SWR on your meter. I can't explain that well. ua-cam.com/video/r6UHITd3AWU/v-deo.html
From the lowest frequency on the MFJ tune upwards until you find the first minimum for R and X, that should occur when you have an electrical quarterwave of cable. (Assuming the other end is open circuit). Don't forget to factor in the velocity factor of the cable.
@@electromechanicalstuff2602 honestly I don’t think the small amount that you’re load is of will matter that much. And you probably have hard time finding one that is dead on nuts right. Hell I’d say a temp change could make it off that much
I'm using a mag mount Stryker A10 antenna.. Stryker 955 radio. When I had the stock wire on the antenna to the radio I had ch1 1.5 SWR ch20 1.3 SWR ch40 1.5 SWR. After I did this the SWR is now ch1 1.2 SWR ch20 1.1 SWR ch40 1.2 SWR. Id say it was a success
@@electromechanicalstuff2602 I'm going from a Stryker 955/Lincoln 2v3 and Stryker mag mount to a Breedlove puck with, at first at least, a President texas antenna and a fat boy 4Xhg2879. I've had the coax and mount for months. Mucho expensive for me to just start hacking. Thank you for a confidence boost
How does my multiband antenna work with a random amount of coax (the distance from the radio to the antenna) and perfect SWR on bands from 80m to 6m? This is crazy. Why don't you just tune the antenna correctly? You are using 27Mhz - just tune the antenna. The coax is 50 ohms, the radio is 50 ohms - so make the antenna the correct size to correspond (PS it will never be perfect).
Totally agree Tom!
My antenna is perfect 1.1 at the antenna.
Your multi band antenna. Is it random bands or is it specifically designed to be bands that are resonant with one another. So in two other videos of mine you watch me change nothing but the length of coax it doesn't even have an antenna it has a perfect match dummy load..... And yet the SWR, capacitance and reactance all changes depending on different lengths. Now let me ask u this. Do you or do you not own an antenna tuner? Regardless of it being external or built into the radio. It does what? It adds either inductance or capacitance to the antenna circuit to make it land on 50ohms right? Ok. Now. If you have a tube amplifier does it or does it not have an input tuning network along with an output tuning network? All my old ones do. Why? If the input tune of the amp represents the load/ antenna as far as your radio is concerned y not just have it at a set tune that is not adjustable? Everyone is going to be using 50 ohm coax between the radio and amp right. So y make it adjustable? It's so u can get the lowest SWR at your radio right? How about the output tuning network. Tune and load right? What is that doing? It's tuning the antenna network for the band you're on right? So yes when I'm running my tube amplifiers it really doesn't matter what length my coax is because the amp has input and output tuning networks to make it as close to 50 ohms as possible.
Now come on over tho the CB world of transistor amplifiers..... Almost none of them have adjustable input and output tuning networks. So u can do one of two things. Open the amp and physically modify the input and output tune to match whatever random coax you are using from radio to amp and amp to antenna or the builder of the transistor amp makes every amp tuned for a null coax. I've done both. I build both transistor and tube amps for myself only. I have even added air variable capacitors to my base station transistor amps. But in mobile situations they won't survive and will get out of tune too often. So we build for null coax because that's the only thing I can make consistent. If you plug in an antenna analyzer and tune your antenna for the lowest possible SWR and it's still too high install a null coax to get it to 1.1 or better. When u install the transistor amp that is tuned for that 1.1 match it will be happy and have absolutely no reflect.
DX commander I love your stuff. I'm very new to this hobby and you're a pro.
I just think that sometimes we get stuck in our ways of it's always worked for me so therefore u must be wrong and it just takes a new set of eyes to ask questions and investigate issues that many people are having but many people just ignore. Yes 1.5 is good enough. But I have always been able to tune my network to 1.1 or better while pushing more power than I care to admit to. The lower the SWR the better your reception will be. That is usually more of a factor for me than loosing a few watts In reflect.
Exactly correct way my friend!!!! Making the coax to be invisible to the system…
On my next video I will make a note and add this link to the description to show everyone how it is done correctly!!!!
I fucked off about 100’ of RG-213-U coax on a mobile trying to get rid of reflect. My MFJ was showing 4 with T and dummy load and I was cutting all my coax too short a couple of inches. I learned a very valuable lesson that week. Great video 👍
Yeah best cut it an extra foot or two long then 3" short. Still waiting on Amazon to sell a wire stretcher
It would be interesting to compare the measurement on a hot and cold day. You will see a difference using the MFJ. It would be interesting to compare the MFJ measurement to a Rigexpert measurement.
I've not heard that but temperature variation is absolutely a real thing. I only have two cb radio set ups so probably won't be buying another antenna analyzer anytime soon
MFJ has to be sent in for calibration periodically.
What length did your RG400 come out to? I got 50 feet of it and I'm interested, so I can use it in my car.
You can not expect perfect result from imperfect equipment!
I agree but it's 90% closer than when I started
As you probably already know, there is another video out there that shows him cutting his coax an inch at a time to get the meter to read Zero. That just adds more confusion to the already confusing question of "how long should my coax jumper be from my amp"....
There is two that I've seen. One was 3made. This is essentially exactly what I did also. I just didn't film it
I am in the process of trying to find how to find a half wave piece of coax to rebuild my Circular polarized 2 meter satellite antenna. That’s how I found your video keep up the experimenting. I have a Rigol Spectrum analyzer and swr bridge. And I done it before just need something to jog my memory 73s from Kc8qdq
Ya there's not a ton out there that pops up in the searches but keep digging and it's out there
Wouldn't cutting coax to zero without the dummy load do the same thing??
@@fredbrauer5429 old video I have a few but essentially I believe that's what I did in this video is cut the coax with dummy attached at desired frequency till coax had no influence on the tune
The electrical leght is the only thing to determine remove the dummy load and the coax to the meter your tuning the coax length with the dummy load you are balancing both to each other. The dummy load has a different reading than the amp obviously it adds to confuse the coax length if you have to use a dummy load put it on the opposite end of the coax did you ever think of checking the amp-. Using the right cap will allow the right reading
I kind of understand what your saying but in the video I do put the dummy at the end of the coax and it produces the same results. The reason I put it on a t at all is because when u are cutting it to tune it's length obviously there is no connector on the end yet. Also I'm not trying to tune the amp. It should already be tuned. I'm trying to add a cable that is essentially invisible to the equipment as to not change the equipment tune. If the equipment is out of tune than that should be tuned with caps and such by itself
If 1/4 wave jumpers are not recommended then 1/2 wave is the shortest jumper length ? The jumper I need is really short. Amp to amp....
I think you nailed it man.
I want to cut one to tune my base antenna with. Its 50 feet now RG8X.
It should 42.3ft by calculating at 27.205.
Which Fatboy Amp do you have?
Straight 8 16D08 hg pills
@@electromechanicalstuff2602 Wow! I have the Stryker 955 also and would like to have some more power. Do you know about how far the 8 Pill gets out at full power?
How close does your coax length work out to calculated half wave length?
@@RC-Heli835 ended up buying a 2 pill fatboy 2879 driver for the Fatboy 8 pill. The Stryker is not enough to drive the 8 pill. Turn the gain way down on the 955. I still haven't put it all in the mobile yet. But with the IMAX 2000 and the rg213 I have ran to it on the base. My antenna is 40' in the air so the tip of the antenna is 64' tall I've talked 40+ miles.
For years and years, the big CB manufacturers have been selling plug and play mobile antennas. In the package is an 18' foot length of coax. Greater minds than ours came up with that formula, so who am I to argue. Ask in any CB forum what length a jumper should be and you will be met with a resounding '6 foot' or multiples thereof answer.
I always use 7 meters pirate cable, works fine for me.
Many things work fine. I just wanted perfection. My SWR is 1.15 at the worst channel and 1.1 at the best channel. This coax tuning is what allowed that to happen. With no other changes I ran a generic coax that came on the A10 Stryker from factory and my SWR was 1.4 at it's worst and 1.25 at it's best. After I tuned the antenna using two different antenna analyzers that gave me the same results.
@@electromechanicalstuff2602 Could it be a grounding problem? You clearly fixed it this way tuning the cable.
@@VicGreenBitcoin unlikely. Because the only thing I changed was the cable. From untuned to tuned. Using a smith chart you can see that inductance, reactance and capacitance will effect your overall tune.
Technically it doesn't change your SWR but it will reflect a better SWR on your meter. I can't explain that well.
ua-cam.com/video/r6UHITd3AWU/v-deo.html
You're theory is correct. MFJ is inaccurate, The best you can hope for is no change and that's as close as you will get.
Do you know how to test how long coax is on a spool with the MFJ 259D?
Can't say that I do. To check it's length right?
@@electromechanicalstuff2602 Right !
@@revbikerbigd8664 I've used my nano vna before to do it
From the lowest frequency on the MFJ tune upwards until you find the first minimum for R and X, that should occur when you have an electrical quarterwave of cable. (Assuming the other end is open circuit). Don't forget to factor in the velocity factor of the cable.
I'm inclined to believe you. Since the dummy load is showing a 6 or 7 on it's own, the
coax is right on. In my opinion, anyway.
Sounds right
Thanks I think also it is right only because my dummy load is apparently out of spec. I'm currently in process of getting a new one.
@@electromechanicalstuff2602 honestly I don’t think the small amount that you’re load is of will matter that much. And you probably have hard time finding one that is dead on nuts right. Hell I’d say a temp change could make it off that much
@@Kc8qdq
Here's a vid on half wave
ua-cam.com/video/ZfXoW26hl_A/v-deo.html
@@Kc8qdq i found out those dummy load like he has will be efected by temp
How did it work out? About to do the same
I'm using a mag mount Stryker A10 antenna..
Stryker 955 radio.
When I had the stock wire on the antenna to the radio I had
ch1 1.5 SWR
ch20 1.3 SWR
ch40 1.5 SWR.
After I did this the SWR is now
ch1 1.2 SWR
ch20 1.1 SWR
ch40 1.2 SWR.
Id say it was a success
@@electromechanicalstuff2602 I'm going from a Stryker 955/Lincoln 2v3 and Stryker mag mount to a Breedlove puck with, at first at least, a President texas antenna and a fat boy 4Xhg2879. I've had the coax and mount for months. Mucho expensive for me to just start hacking. Thank you for a confidence boost
Just subscribed to your channel. Seems like your a year or two ahead of my knowledge. Thanks for the feedback. Will be following