Coax switches - The good, the bad, and the ugly!
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- Опубліковано 27 тра 2022
- Let's take a look at a couple of common coaxial switches. Can you use them for switching a radio as well as an antenna? SPOILER - yes, yes you can.
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Nice comparison, glad I finally found the time to watch this Jim.
Glad it was helpful! There's a lot of emotion on these things. It either is, or it ain't, as far as I'm concerned.
Very good analysis ... great video and audio was clear. Thanks. Murph
Coax switches are easy made your self. All you need is a good ceramic switch a box and common RF sense for the layout. I have build RF switches with 8 or 12 ports good for 3kw and up to 500Mhz. If you just want to use it for transmit into an antenna 40-50db isolation is far enough. I never had a failure. The Alpha Delta, as good as it is, has the problem that the metal taps get hot when used with high power at VHF or UHF and will possible de-solder itself. I had that happen using legal limit on 432. I build my own and never looked back.
* MHz * dB * kW Everywhere and always. If the symbol is a name (Hz = Hertz, B = Bell, W = Watt), then the symbol is almost always uppercase (very few exceptions where they ran out of letters). Cheers.
I made my own jump box with coax jumpers and barrel connectors. Radios on one side and antennas on the other. Simple and solid.
Certainly a cheaper solution than buying one of these things, Chuck.
Grounding will be effective through the braid of the connected coax cables which are grounded to the radio/s and then through the mains supply ground (in the UK). Very nice informative video, thanks. G0 LQU
I also prescribed to this theory. Usually don't see anyone talk about it. As long as all the coax meet at the common station ground, I would think all is well. Adding additional ground strap or wires could create high frequency ground loops?
Thank you for the time and effort, I now feel validated about buying the cheap switch lol, don't need a lightning arrestor due to the HOA causing me to put several antenna into the attic, nicely done analytics. Liked and Subscribed
Glad I could help
Daiwa and Alpha Delta are the Best Coax Switches made. Nice Video, thx for sharing this with us. 73 de Your Friend Uncle Guenter 💯👍🍻🙋♂
Some sort of gas thing, I love it. Great video thanks.
I have replaced most of my switches with alpha-delta for the build quality. I have had a 3 of the other type of switch you show fail with minimal use (less than 10 switch-overs) - it becomes stuck.
The cost of the Daiwa and a quality coax lightning arrester outside the shack make that a far more economical choice. Plus, it keeps the potential lightening strike outside of the shack.
Pretty much my thoughts. Inside, pot metal is pot metal. Ground is ground. The gas discharge in the AD is cool, and a nice safety feature. But, as you said, a decent lightning arrestor and the daiwa will do the trick as well.
@@FEPLabsRadio Gas discharge is quite useless if there is a different dc ground path.
You’ll still need a separate lightning arrester for each coax, all bonded to a single point ground, before bringing your feedlines into the shack.
I I’m not mistaken, when the Aloha Delta switch is selected to one port, the center of all other ports goes to ground.
Alpha Delta has more electrical surface area at the contact zones.
I see a way better engineered in side of the Alpha Delta. I see over $100 of difference between the 2. I will only use Alpha Delta 2 or 4 antenna switchers. I have way to much $ spent on my Yaesu FT-DX101MP SDR rig for a cheap part to destroy it. But great video and info. thinks for opening the switches up to see.
Same thing here, I have a Yaesu FTdx-3000 and don't want it destroyed by a cheap coax switch, so I use an Alpha Delta-4 with it.
that Alpha Delta is made in a Chinese factory, just like the other switches.
Thank you!
I use a Zetagi v2 which is a manual 2/1 switch, works great & I believe cost me around £20/$25, they handle 500w Am/Fm.
Good to know! Pretty much, an electro-mechanical switch is the same as every other one. Some models have some fancier build, but at the heart of it, good wiring and connectors do the trick. I use the cheap ones I showed nearly every day.
I have an Alpha Delta-4 coax switch. I don't intend to transmit with more than 100W but I wonder if at 1000W plus the results would be the same. Thanks for the tests.
I can't remember off the top of my head what the max power rating is on either of these at the moment. As far as the difference, I've only got 100 W rig here, so I can blast it with 1Kw. looking at both of these side by side, there's just not enough difference between the two that at 100W it would make any difference (and it doesn't, in my testing and usage).
well done
Hello there. I’d like to ask if you actually tested continuity between center and chassie of the common (center) port with switch in the middle (center or common position). As far as I can see from the inside view, the hot center is not in direct contact with chassie but through the gas discharge tube. If so you won’t have continuity when testing. If a surge would occur the gdt would blow and create a path to gnd. That’s the case of an antenna connected to the common (central) port.
If used the other way around, one radio to the central port and multiple antennas, are the non used antenna ports actually grounded?
I might be wrong but for what I see they are not, they are floating, waiting to be connected to the common port when the switch is moved. If the antenna outside hasn’t a DC path to earth, static charge buildup may occur.
You checked dc isolation with your tester between ports but I believe you didn’t check the unused ports center to gnd.
Could you give me more informations based on my comments?
I have a Daiwa myself and I’m happy so far.
Bye
Diego
The Alpha Delta actually has all the connectors connected to ground when its in the middle position. The Daiwa when in the middle position, none of the connectors are connected to ground. It's only grounds the unused port when the other is connected. I wouldn't trust the Daiwa in the middle position because the inputs are floating.
Thing is - it's a switch. put a dummy load and roll on - i'm not buying it to ground all the lines together. Sure, the A/D has everything grounded together in that center position, but I don't see a practical use case for that. Like I said...my point is that between the two, switching isolation is exactly the same. For all intents and useful purposes, the Daiwa switch is just as good.
@@FEPLabsRadio Au contrair, it has a big practical use case. If you are using it to switch between multiple antennas, you don't want the unused antennas not to be grounded out, because you can get a huge static buildup on the antenna, not just from thunderstorms but practically anything. These can be high voltages which when switched to the receiver it is possible to blow out the front end.
@@ronwolenski-n8wcr wouldn’t the antenna be grounded/the static electricity have a path to be bled off through its connection to a lightning arrestor prior to it coming into the shack? Or am I wrong on that? The screw collar of the connector is a metal contact to the arrestor threads which are attached to the metal body which is mounted on the metal plate on the box coming into house which in turn is attached to a ground? Shoot, I should just go out later and check that there’s continuity but assuming there is, then isn’t the antenna always grounded separately of the switch? I get if one didn’t have a lightning arrestor setup then there would be no ground prior to the switch and the switch would be the only thing.
Edit:typo
@@pfmcdermott1 I think you are confusing a lightning arrester with this type of switch. The coax shield is grounded because it's all metal. In the A or B position, the antenna connection, the middle conductor, is not grounded, nor is it bleeding any static to ground. However, on the Daiwa switch, if you put it in the middle position, the middle conductor of both inputs are shorted to the case and grounding out the antenna. It's not a static bleed, it is just a direct short and you cannot transmit when the switch is in this position.
Actually if you put the Daiwa in the center position the two switched ports are grounded to the body of the switch through the center metal block that rotates and that block in turn is touching the housing on the front and the metal plate on the back that it rotates on. However the common port is not. Having said that, I only use Alpha Delta switches.
I’d love to know the SWR with that Diawa on 2 meters. That’s what I’m needing right now.
Damn. That's a lot of money for a simple switch box! 135 dollar!? I will build my own for that kind of money! 😅🤷🏻♂️
Yup. It's the same metal. It switches. No gold or magic leprechauns inside. For that much money, I'd at least expect LED's on it.
I own the 4 port Alpha and like it but honestly inside it looks like it should cost about half of what it does! Wonder what a MFJ looks like?
I agree. There's not that much difference between them IMO. Other than the lighting arrestor dingus in the AD switch, it's all the same pot metal in both. Well, also the AD has a detent for the ground position, but really, the construction is pretty much the same stuff.
@@FEPLabsRadio The specs aren't the same. That's why the AD costs more.
I have two radios connected to the Delta2 using one antenna. With both radios on I wound select one radio and when I transmitted, I would get bleed over from the other radio. Email Delta and they said that was normal and to stop the bleeding I would have to turn off the other radio. I didn't like they answer. I purchased the MFJ-1704 same design as the Delta4 with no problems at all.
Interesting. I've had the same basic setup, and I literally just turned the other radio off. I noticed that my IC-7300 was more susceptible to front-end overload than my 991A was. I'll have to look at the MFJ product and see if they have some filtering in there (probably do).
Totally off topic... where did you get the mat you are working on? And thanks for the great explanation of switching for antennas.
Amazon - where I get everything! LOL - amzn.to/3Vif0dP
You say that center position on the Alpha Delta is straight to ground, but I dont think its a ground position. just common antenna or radios.
Right - well, you would normally have the switch grounded directly, and the metal frame is bonded to the ground lug - so it is grounded.
pretty good review overall just a couple of errors that need to be corrected. The new version of the MFJ switch or dawa has a center detent and they ground all the unused ports.
The MFJ version is actually better than alpha Delta, alpha Delta switches are highly overrated and have well-known issues with overheating and deeperring of the contacts.
The problem with the alpha Delta switches is the almost negligible surface area between contacts, they're using the edge of a piece of beryllium for contact or as the MFJ switch actually has contact points with substantially more surface area.
the alpha Delta is known to have overheating issues at the contact points, they've been known to desolder themselves they get so hot again this is because of the small amount of surface area on the contacts.
the dawa switches the MFJ and dawa switches also have better 50 ohm strip line performance, The alpha Delta demonstrates impedance bumps.
another issue is the arc tube, you definitely don't want to use an arc tube when switching wire antennas that present high SWR.
In other words with the alpha delta you can't put a tuner on the common output and switch between high SWR antennas expecting to tune them after the switch. alpha Delta switches do not tolerate SWR higher than about 1.5 very well or the arc tube will begin to overheat.
with the alpha Delta switch you'd have to put a tuner on each output to each antenna with the MFJ you can put the tuner on the common and switch between various antennas with high SWR.
So the bottom line is the alpha delta is limited to use with resonant antennas and at nowhere near legal limit because the surface area of the contacts simply cannot handle it.
The alpha Delta switch is way overrated for what it is, mainly by people who think that since they're paying more they're getting a better product.
Wow these prices have jumped up in a year.
The contact surfaces looked smaller than expected on the alpha/d especially. Didn't see in the comments that your, intended Edit around 22: 53 didn't happen at 22:55 - 26:42. FYI
Hey Richard, thanks for watching! That is one of my older vids, and my editing skills have improved quite a bit since then. Hopefully it wasn't too cringey!
So the shack ground on the 4 way depends on 4 small screws? Earth terminal should be on the case.
Yeah, the ground is the case, so you'd tie that to your shack ground.
@@FEPLabsRadio Very bad design. The case should have a better earth connection. Of course, that might cost money.
My hf and vhf antenna are about a foot apart both on chimney ... right now i discknnect the radio not in use .., questin is would a swutch like this work as a dissconnect or are the contacts too close togeather to be truly disconnected? I want a swtch vrs unscrewing the coax everytime or recommend a switch that would work
If I remember, it's about 60db of electrical isolation. Unless you're running an amp at 1Kw or more, it should be fine.
Thank you @FEPLabsRadio
Diamond cx210 or cx310 would be cool to see, also.
Noted!
Can these switches be used for gmrs ?
Yes - there is no frequency dependence at all.
Simplicity and reliability count.
Pretty shocking seeing the Alpha Delta on DX Engineering in your video from a year ago for $83.99 and looking today and its $119.00
Yeah, apparently they age like fine wine?
that daiwa is much better quality, instead of simple copper laying on copper for a connection, its actually using proper contacts!
That was the first thing I noticed. If those strips ever got out of line then what?
Not to sound ignorant but I have never used one of these switches, can I use them for two radios and one antenna?
Absolutely! That's mostly what I use them for in my house. I have a DX Commander outside, and the coax comes in to the house, I switch it between a IC-7610 and a Kenwood 570D
Is the NanoVNA software running on a Mac? If so, do you have a link to it?
It is the software for the librevna (which is what i was using). librevna-gui is the name if it. nanovnasaver is the software for the nanovna, and works similarly. Libre - github.com/jankae/LibreVNA Nano - nanovna.com/?page_id=90
@@FEPLabsRadio I thought I heard you say Nano when you are connecting it up. I assume the Libre software won’t work with the NanoVNA
@@JohnVK5JAK I don't know, it might. I suspect not, but hey, they're both free apps, might be worth a try.
I use Bird coax switches in my shack, much better quality.
Considering that lightning arrestors are CHEAP, who would choose the Alpha-Delta over the Daiwa? Besides, a lightning arrestor should be installed OUTSIDE the shack....do you REALLY want 20,000 amps slithering down your wall, to ground?
I agree with you on that - I want the lightning arrestor outside the house. Of course, a direct strike will make both of these things cook - the direct voltage would not even slow down.
How are these so expensive? It's just simple wiring, not extra electronics or complex engineering.
Exactly my point on it. Of course, the AD is a 4 port, but underneath the hood, it's just very basic components, and there's not any real difference electrically. As long as the switch switches, good to go!
0:45 "Electric/remote switches are not bi-directional" Huh? As written it is overly-broad to the point of being incorrect.
Remote-controlled coaxial relays are every bit as bi-directional as any manual switch. They're basically a switch controlled by a solenoid, as opposed to a knob. No difference to the RF inside.
I think you were referring to a specific type of Electronic RF switch, but you accidentally also included coaxial relays.
My mouth got moving faster than my brain.
They're all crap. Bird Coaxwitch is your friend. (Though not your bank account's friend :-)
It is "D tent" not "detente." Ron W4BIN
Potato, potato. ;)
thanks for watching.
@@FEPLabsRadio
Actually, not potato potato.
But I know you know this. :)
de·tente
noun
noun: detente; plural noun: detentes; noun: détente; plural noun: détentes
the easing of hostility or strained relations, especially between countries.
"a serious effort at detente with the eastern bloc"
Diamond is a tick better than both of these
FINE COMPARISON OLD MAN.73,S DE VU3MJF/HANDLE: AIRFOX