An antenna switch at a electrical level is just a simple single pole, 4 port switch. At DC it just connects to each port. However, at RF frequencies, that is totally different. You see that there's long connectors that aren't shielded side by side, which will insert inductance between each leg. At HF frequencies, this is unnoticeable, however at higher frequencies it will come into play because of the shorter wavelengths. This is why these switches are for HF use only, not UHF or higher. Most switches will short out the unused ports to ground so there are no inter-reactance between the ports. For UHF and higher frequencies those switches need a different construction to not introduce any inductance.

Thank you for posting this. I've been using my AD4 for many years now on HF only without any knowledge of its effects. Now I know. :)

Thanks for sharing Ape!

Thank you. I have used mine for years to switch from my antenna tuner to four different radios. Very happy with it. Alpha Delta makes excellent products. Higher prices but quality.

Neat product. Agree better than a magnifying glass for some bench/tabletop projects. Also, looks like good utility for school use. Thanks for bringing this up.

Awesome test. I learn a lot about what the Nano VNA can do by watching your videos. Just bought the exact same switch last week. Working great, but I did see my SWR up .1 on VHF, and may .3 on UHF. All still below 1.5 at any given moment to a KB4VBR J-Pole in my attic. Appreciate your knowledge. 73 KN4VA

I just got an Alpha Delta 2 port switch to connect 2 HF transceivers to one antenna and was pondering the port isolation and risk of damaging a radio. I decided to do some research found this video. Exactly what I was looking for! The -34 dBm figure made me a little uneasy, but the real world testing at S5 was not too bad. I normally operate at 50 watts or less, so I should be OK. Thanks Ape!

Who's the nerd now? Totally dig the comprehensive testing and analysis. I know so much more about my Alpha Delta Delta-4 switch. Didn't even know about the 2:1 limitation, and here I was running 100 watts with full reflection through it.

Great test, thanks.

Very well done

I have a couple of those. I currently use one to switch my two hf units between my vertical. I have had zero issues. One unit is a 7300 the other is an ICOM 706MKIIG. I have used the hf unit and then transmitted on the 2m/70cm part of the 706 (the 706 has a separate antenna port for 2M/70cm) at the same tiime with no issues. i love those alpha delta antenna switches. They are built like tanks. Cockroaches will be using it after I am dead from the next nuclear blast. Great video Ape! 73

Hi, I am so grateful you did this test on this switch because I have grown increasingly concerned about my high SWR and where the problem we’re coming from? It was a number of things which I have sorted but I was so shocked to see so much coming from the Alpha Delta Switch on 2 m. Your demonstration explains and helps so much one thing I will say that you might need to take attention too! you were testing on the outside sockets . The two inside sockets were twice as good as the outside sockets and were manageable. 😮 I don’t know about the isolation though.

i have one of those, and i love it

A nice demo of insertion loss/port isolation of the 4 port alpha delta coaxial switch. The brief setup using the ic705 and 7300 is fine. As you concluded the switch is good for HF with 100w of RF. At 23.06, you said ic7300; it should have been ic705. De VU2RZA

Another enjoyable bit of education

found your Chanel ! love every video you made! It's very interesting your opinion on FPV DRONES antenas, extensions, multiple frequencies antennas and vip anti-drones antennas ? sure FPVS FANs do appreciate your expertise ! thanks again

I've always wondered what the inside of my Delta switch looked like, and now I know thanks to TheSmokinAPe. I don't think I follow that SWR limit 😏 Added Comment: Okay, should have watched to the end before commenting. Really like the isolation test. You come up with things to test, that matter, that many of us never really think of. Thanks again for the really great work in growing our knowledge base.

Very informative, thanks. I disconnected mine because I know my antenna is not 2:1 without a tuner on 40m and 80m. I might find a way to connect it differently but I'm fine without it. I wasn't using it to switch external antennas. I used it to switch my antenna from my rig to my SDR USB dongle. I'm using 450 ohm ladder line to a dipole about 100ft in length. Surprisingly, my rig's internal tuner works on all the other bands besides 40 and 80. It even tunes 160m (which I don't use anyway, but interesting nevertheless).

Excellent video! I'd be interested to see a comparison to something like a Bird 74. I realize it's almost apples to oranges as far as price and build quality is concerned, however the vna doesn't lie about performance, 73!

Ape great video. I few things i saw is at the end with the 100W ic 7300 705 test, the 705 seems to have the RFG in red which means the RF gain is reduced, Also with cable loss that why the signal is S5 not S9 on the 705. Great video though!

I've developed distribution buffers which exhibited over 100dB of isolation. Fun times.

nice testing. I have the Delta 2. I switch between dummy load and antenna. I tune my tube amp into dummy load first. gets me real close. less over the air tunning. that spacer insulator piece is below the arc plug on mine. I don't have base setup any more from moving a few years back. Just portable now. still use the switch in testing. I may take it portable and run 2 antenna's or dummy load on 1 side to tune up. that I have done. just not 2 antenna's yet. the switch now lives in my POTA kit. that way I have it if I need it portable. I want to get the one with N connectors for testing UHF. 73's

you can also hook up 4 radios to one antenna, the ports are bidirectional

your next switch review should be the mfj-2704 it grounds the antennas center pin when not in use to keep static under control.

Wut? No RGB LED walls in the background? No bright backlight or cute bookshelf with collectibles? No side light making one ear and cheek shine white? No 12min intro before you say “let’s jump right into this?” How do you expect us to trust your video. [Except, of course, I have one and my curiosity found same results and it is my goto switch for HF.] Thank you for the fabulous SNR of your videos.

Seerus testin! If I was doing 1500w, I'd have a patch panel instead of a switch.

If you run some tests again and instead of just testing port 1 and 4, test ports 1 and 2 or 1 and 3 and you will see a lot more variance in your numbers. I ran some of the same tests on my companies HP analyzer and I was surprised. For example, the SWR on ports 2 and 3 are MUCH lower than on ports 1 and 4 the higher the frequency. I believe it has to do with the length of the strips that make up the connection paths and possibly the interaction with the "walls" that are much closer on ports 1 and 4 where there is a larger "air gap" on ports 2 and 3.

Ape, on the higher frequencies, would you not be using N type connectors vs PL-259/SO-259? Would that change the higher frequency results? They do make this switch with both SO-259 and N connectors.... BTW. Personally I do like the Alpha Delta switches and have used them for a long time in the shack. Art W1SWL

Great report. However, at 20:28 the symbol with reference to the dB isolation is "greater than", not "less than".

Might have wanted to look at the instruction sheet it states that a ground is required for the switch to work properly. You had a floating ground so the un used positions really aren’t grounded. Wonder what difference you would see especially at the rated 1500 watts?

Full legal limit, 1500W is just under 62dBm so going by the data sheet isolation you're at most looking at +2dBm into your receiver. As you measured, it may be significantly less. The damage level for most LNAs on the market is typically around +10dBm so you should have headroom even on a bare LNA. However, any well designed modern transciever will include an RF Limiter just behind the T/R switch. These devices will often kick in around +0 dBm or +10 dBm and clamp the output power to protect anything down the chain. Even a tiny chip limiter mounted on the board is often rated for a maximum power of +33dBm or 2W. Remember your transceiver or amplifier has a T/R switch which probably exhibits 40-70dB of isolation, similar to the specs for this switch. So your receiver was already designed with these power levels in mind. Running a kW you may risk damage to a cheap, no name, e-bay receiver built with no concern for anything out of the nominal case, but any circuit designed by a competent engineer will be fine. On the high frequency performance I'm a little suspicious of the measurement setup, specifically the nanoVNA. If you notice the noise at higher frequencies begins abruptly both with the switch and when connected directly to the load. An effect caused by a simple component like this would much more likely exhibit a gradual increase in noise with frequency, there's not really anything in here that should cause a step like that in the frequency domain. I believe the nanoVNA may utilize aliasing for frequencies above 300 MHz. It is easy for something to go wrong there and introduce additional noise and a compromised match. Perhaps I'm just spoiled by the high quality test equipment I use daily at work, but I would be very careful attributing blame to the switch in the higher frequencies when the measurements look like that. All in all a nice video. From a professional perspective I wouldn't have any concerns using this switch in almost any HF or VHF amateur radio setup. If you're looking to do UHF work I'd use the other models that Alpha Delta offers that include N connectors rather than SO-239's. The SO-239 / PL-259 connectors were never designed to present a constant impedance, and while they're fine at lower frequencies, they are not suited at all for work above a couple hundred MHz.

I need to get one of these. I have a 10M transceiver & a FRG-7 that I want to share the same antenna. So, the antenna goes to the center "common", but do I need to add dummy loads to the open ports? Thanks

Is the chassis ground connected to the so 239 grounds? If so all of them or just the common port? Would connecting the chassis ground to an earth ground change the test results? Would bonding the 2 radios to the switch chassis and earth ground the switch chassis affect the results? I wonder what effect 1500w would have on the tension and connection of the metal tabs? I think for the common ham this thing would work just fine. Thanks for breaking the seal!

Dear Ape, first, thank you for another great video. My plan for this switch was to go between a DX Commander for transmit and a Loop-on-ground or Delta loop for receive. With an S5 reading on the port that is “off”, would this harm some antennas that are designed for receive-only? If this appears to be a noob question, please forgive. Respectfully, KQ4IXD

Hi Ape, awesome video! What you said about the 2:1 SWR limit for this switch makes me think that the best type of tuner for non-resonant antennas would be a remote ATU like the MFJ-993BRT, ICOM AH730 or similar where the ATU is installed outside at the antenna feed-point. TBH I'm not sure what I think about a setup like this, I would be inclined to avoid all that complexity and use a resonant antenna like an EFHW or DX Commander. Cheers! Jan M7HNK

It would seem to me --- you miss spoke at about 14:50 " reflected back " ? Nothing is perfect [ the MFJ dummy load , so there maybe some / but little reflected signal ] --- a dummy load absorbs the signal & turns it into heat & is radiated through the fins on the dummy load ? Thanks

so, this switch does not short unused ports to ground?

I have two of these and my SWR is an issue when installed.

As you measured "only" an S5-signal in the practical isolation test with the two ICOMs: There's a video from a German amateur DL2YMR over a year ago where he found out that the S-meter in the ICOMs (in other radios too but he tested the ICOMs in the video) are very "corrupt". In this part of the video (kzfaq.info/get/bejne/rLqCm7tnq5rYpJs.html) he injects an S9-signal to the the IC-705 and attanuated it to an S8-signal. But the IC-705 indicates a S6-signal (assuming his equipment is OK). I don't know whether it is fixed in the meanwhile. I wanted to share this because you seemed to be surprised about this results in 24:25.

Something to add; The arc plug is only engaged when one of the ports are selected. When selector is centered, all four port center pins are grounded. When one of the four ports is selected, the other three port center pins are grounded, If using switch for radio selection, you must take caution in which radio is NOT selected.

I think there's something wrong with your setup, possibly bad jumper or poor quality dummy load or adapter. I just ran these same tests on an agilent vector network analyzer and got much different results, insertion loss it for 437 was 0.4 dB isolation between ports at 437 was 60 dB At 900 MHz insertion loss was around 0.7dB and isolation was around 55 dB I would double check your setup and calibration and rerun these tests.

freakin hell, you dont get much for 100 bucks

I really like your videos, but it hurts me every time you say "one mega hurt". The dude's name the Hz unit was named after was Heinrich Hertz. So, it's always (mega, kilo, whatever) Hertz, with an audible 'Z'. No matter if it's only one. I didn't mean to be rude, as I said before, I really like you videos for their information value, but I just had to get this off my chest.

Sir, if you deem that there would be sufficient interest, would you please make a video on antenna combiners. I have (I use) multiple antennas, of different types - for my scanners. I am finding that it's a complex issue, when it comes to combining multiple antenna inputs to 1 scanner. The data sources 'seem' to imply that this is not a good idea, that 1 antenna used on 1 scanner is the best route to follow. Then again, other sources speak about different cable lengths (problems) of different antenna types (more problems), of having too much 'input' which may overload the front end of a scanner. It goes on and on and on, and there is NO apparent clearly defined answer. The bottom line: what are the pros and cons, what are the problems of trying to combine multiple antenna inputs to drive a single scanner. Sir, additionally, if combiners (active and passive) is not a sufficient topic for a video, would you consider speaking about signal amplifiers - I actually use multiple dedicated radios (marine radio, aircraft, cb) along with the multiple scanners. After combining the signals from this myriad of antennas, if I then wish to split the combined signal to 3 or 4 scanners (or different radios) what is the issue with powered/active signal amplifiers? Am I able to use a powered active signal amplifier, split this signal, and then split it again to 3 or 4 radios? Questions, such as; can I overpower and damage the front end of a radio/a scanner if I have too many antenna inputs: can an amplifier damage the input of a radio, using cables of different lengths and antennas of varying types - is it better, as in best performance to simply have 1 antenna per radio. In close, I see that many of the truckers use multiple cb antennas - for better distance 'getting out' issues. So if multiple radios for truckers/for cb is a standard and accepted practice, then why would there be an issue using multiple antennas for receiving. (only receiving) Thank you, Sir: I am a subscriber, as your channel has value - to me.