Attenuators Explained for Ham Radio Beginners

In this video we will talk about how we use attenuators when testing Ham Radio Equipment.
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10w 40dB Attenuator: amz.run/5h5J
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[@HamRadioPrep]

Another great overview - easy to understand about a part many people are probably confused about. Thanks Ape!!

[@TheSmokinApe]

Thanks man, much appreciated 👍

[@gsahookah599]

Great video and well delivered, as usual! To prove that I was focused and paying close attention, I would like to point out a minor correction; *chuckle*, you mentioned that your Siglent 3021X is a 21GHz Spectrum Analyzer. However, it is actually a 2.1GHz model. NOTE: I'm just having fun; we all garble our thoughts sometimes. I love you man!

[@TheSmokinApe]

Haha, thanks GSA 👍

[@AD6DMDennis]

Reminds me of when I gave a S2S contact a 229 on CW when I accidentally left the built-in attenuator on.

[@TheSmokinApe]

ha!

[@tomking8597]

Great job. I used to sell attenuators and test equipment. You did a great job showing how to use the. Next show a directional coupler. A great way to test your power meter Have a great day

[@TheSmokinApe]

Thanks Tom, much appreciated 👍

[@mariofilippi3539]

Tnx OM for the excellent review of attenuators and how to use them properly.

[@TheSmokinApe]

Thanks Mario, glad you liked it

[@derbemobile]

Thanks for the video. I just got a TinySA Ultra. This gave me the patience to wait for the attenuator 😅

[@TheSmokinApe]

Yeah man, you don't want to let the smoke out!

[@tomyeast3438]

Thank you so much! I was vague about how to use the attenuator, but I'm sure I know

[@TheSmokinApe]

Glad it was helpful Tom 👍

[@jonathanhensley896]

Man this is a banger! Ive been learning and messing with SDR. I can understand how you explain things.

[@TheSmokinApe]

Thanks Jonathan, glad you like the videos 👍

[@KateHikes1933]

How much attenuation should we need to protect a signal analyzer, such as the TinySA Ultra, for example? And how do you know--does each analyzer give a maximum input? Thanks for the video.

[@TheSmokinApe]

@@KateHikes1933 the max for the TinySA Ultra is +6dBm but you get the best results with about -25dBm.

[@HOAHamRadio]

Test the test equipment!

[@TheSmokinApe]

Gotta keep it honest 💯

[@deankq4adj125]

Excellent video Ape, cleared up a lot of questions I have about using these devices!!

[@TheSmokinApe]

Awesome Dean, thanks for watching bro 👍

[@g0fvt]

Well presented as usual, observing the correct input/output connections is of most importance at significant power levels, for example if your friend had perhaps a 10dB 10w attenuator it would likely be destroyed by a 5w radio connected to the wrong port. High power attenuators of significant attenuation are a better investment than dummy loads because they are effectively dual purpose. IE I have a 2kW 40dB attenuator, which serves both functions well, of course I can optionally put a terminator on the output port but with that level of attenuation it is not really essential. A function of attenuators that is often overlooked is to normalise impedances, for example for testing a receiver using a signal generator there can be merit in using an attenuator at the receiver input to ensure that it is seeing a 50 ohm source. Of course messing about with antennas can be made safer for the radio by temporarily driving the load via an attenuator. Very useful pieces of test equipment. 73

[@TheSmokinApe]

Hey g0fvt, I agree with all that. Nice tip on using them with the sig gen 👍 thanks for watching 🍻

[@robertmeyer4744]

great job. I have amazon ones defective from new had to send back. they do heat up. I think power rating is ICAS on them. for high power testing I go threw a line section into high power dummy load. the line section give me a tap and still use attenuator to drop even further for test . for UHF and down to HF what you showed is just fine to work with .when working full legal power I found it best a line tap into dummy load. this will get quite hot. this keeps happy transmitter at 50 ohm load. you can even add a line tap to MFJ dummy load . but even at 1.5Kw still need attenuator to input to a tina SA of something. you just have to add all attenuation together to subtract from reading. Tina SA can do this just buy adding that attenuation into menu. 73's

[@TheSmokinApe]

Good info, and yes I have known a few people to have the Amazon ones go bad 👍

[@DavidJohnstone-hi9kr]

Thanks for all the great videos! I’ve learned a lot about RF test procedures and equipment by watching them. I bought a new open box no-name Chinese “big ass” attenuator (50dB 100W). I’m not sure if it’s directional since it doesn’t have a label indicating such. I’ll use a “rule of thumb” I'll put the input on the female N connector, until I verify the attenuator with a VNA. I know to have the highest power attenuator closest to the RF source. Could an RF attenuator (like the “big ass”) be used as a dummy load? Maybe putting a metal cap on the output? What do you think?

[@TheSmokinApe]

Hey David. That big ass attenuator is pretty handy, good luck with it... you can use them before a dummy load which means that you can get a smaller least expensive one.

[@Inkling777]

Can you use these to reduce your transmitted power? For instance, if you had a 10-watt transmitter could you use a 10 db attenuator to reduce your transmitted power to 1 watt?

[@TheSmokinApe]

You can use them for that but it would also attenuate the RX signal 👍

[@mandytuning]

Does it have to be bidirectional or directional?

[@stampydragon2739]

Could I use a 10dB attenuator to transmit on PMR 446 if my radio puts out 5w

[@jcvee15]

Thanks again for another great video. If one doesn't have a Siglent, is there a way to test an attenuator like you did with the Tiny SA Ultra or a VNA?

[@TheSmokinApe]

Yes, do a logmag test from port 0 to port 1 on the VNA 👍

[@K3JRZOnTheAir]

Great info! Thanks! 73!

[@TheSmokinApe]

Thanks JRZ 👍

[@AMG-502]

I really appreciate your videos. I do have a question about attenuators, my TinySA Ultra and testinf 5 and 10W HTs. So the best i can tell is i need to get the rf db down to -25db before feeding into my TinySA Ultra. I have a mix of 5w and 10w HTs. This seems to bring me to annattenuation needs between 60db (for 3.5W) - 66db (for 12.5W) of attenuation before connecting to the TinySA Ultra . My question is can i buy a 50w 50db attenduator and connect it to a 2w 20db attenuator connected to the TinySa and use this with 70db total attenuation for HTs between 3.5w or 12.5w units of TX power? Any advice is appreciated. Thanks in advance.

[@TheSmokinApe]

That should work just fine, just make sure the 50w is closer the the radio 👍

[@satishriyapatel8362]

Pls purchase link send

[@oldblokeh]

Hi, great video, thanks. Could I ask you to clarify why you'd want to put the highest attenuation on first when stacking them? It occurs to me that if you had, say, a 3 dB 10W attenuator and a 40dB 10W attenuator you could use them with a 20W source if you put the 3dB one first. It would dissipate 3dB i.e. 10 watts leaving the second to dissipate the other 10W. The other way round would have the 40dB attenuator trying to dissipate pretty much all 20W.

[@TheSmokinApe]

The resistor in the first 10w attenuator would cook if you push 20w into it. You would need at 20w or more attenuator to handle the 20w out.

[@oldblokeh]

​@@TheSmokinApe That depends on whether the rating is for maximum input power or maximum dissipated power, surely. A 3dB 10W attenuator will dissipate 10W of power when fed with a 20W signal. If I look at series of readily available attenuators, all of them them the same power rating seem to be the same physical size, regardless of attenuation factor.

[@Mr.Leeroy]

Have you tested temperature rise compared to power ratings of these 10-25-50-100W CN attenuators?

[@TheSmokinApe]

I have not

[@nol_yaw]

i am using a J pole antenna connected to a RTL-SDR dongle and RSPdx i am getting a overload or something but my spectrum in any sdr software will go all crazy on me about every minute or so and it seems to be worse when i'm around stronger signals would this help stop that?

[@TheSmokinApe]

It would but it would suppress all signals

[@chrissewell1608]

Can you add on of these inline with a Yagi antenna, for Fox Hunting? When you are close to the transmitter, and the signal power is over driving your reciever, and you can't narrow down a direction any farther.

[@TheSmokinApe]

Hey Chris, you can. I'd look at the step attenuator so it's easy to switch levels 👍

[@chrissewell1608]

@@TheSmokinApe Thanks!

[@formeolosuslasvenators1777]

I am very new to this technology, was given a tiny SAultra, do you know how i would set it up for sniffing” or foxhunting? Directional antenna? Attenuate the input signal at the high or low input between ant and receiver? I obviously aren’t well versed but would appreciate the feedback. Thanks.

[@Swede_4_DJT]

Greetings from Sweden! I will get my tinysa ultra soon. If i buy 3 attenuators which ones do you recommend i buy? I will test some 1 to 6w handhelds and that's it so far.

[@TheSmokinApe]

You should get 40 and 30db attenuators for 10w

[@Swede_4_DJT]

@TheSmokinApe Thank you, Sir! Much appreciated 🙏 Maybe some are stronger in w, i will starr on the Quansheng UV-5 (6) 8 or whatever it's designated now. But i guess it's no more than 1-2W on low power. Sold all my radiis and just returning to the hobby.

[@TheSmokinApe]

Welcome home!

[@ShoMoto-ko1ix]

How do you test that the attenuator is working properly? Your buddy's failed. How did you test it? Thanks.

[@TheSmokinApe]

I actually just did a video doing that, you can also do an S21 test with a VNA. Mini Circuits SMA Attenuators: Everything You Need to Know kzbin.info/www/bejne/nYLQeKqCadVjiq8

[@mrtechie6810]

I have a 6GHz dummy load. How can I get a proportional sample into the TinySA from the transmission line to get an accurate power measurement?

[@TheSmokinApe]

You need an RF Tap or Directional Coupler, I have a video showing how to make an RF Tap 👍

[@Bill-HRT]

Hey, Ape! I am paying attention, Professor!!! Eventually it'll sink in . . . Thanks for the video! 73 de Bill

[@TheSmokinApe]

Lol, thanks Bill. I appreciate you watching 👍🍻

[@MrMario123ah]

Hello. I have tinysa and what attenuator should I purchase? 25w40db is OK?

[@TheSmokinApe]

That’s a good place to start, I wouldn’t put more than 5w into it. The TinySA has a 6dbm input.

[@karlbesser1696]

Hi Ape, do you know of a sensible use for a 'Throughterminator'? This has an impedance of 50 Ω at both the input and output.

[@TheSmokinApe]

I have one that I use to connect the 50ohm coaxial cable to the high impedance (high z) input on my oscilloscope. I’m not sure I’ve seen a 50-50ohm one

[@karlbesser1696]

​@@TheSmokinApeAt 3.6 MHz the transmitter (generator) is practically loaded with the nominal impedance of 50 ohms (exactly it is 49.97 ohms |_-1.13°) if you have an oscilloscope with the usual 1 MHz || 20 pF is connected to it. If you work at 1 GHz, the transmitter sees 7.86 ohms |_-81°, so not a good load for the transmitter. By the way, the center conductor is connected through and probably has a 50 Ω coaxial resistance to the outer conductor. Have a good day.

[@gartnl]

Regard it as a low power dummyload. Basically it is a 50 resistor between live and neutral. So it is a 50 ohm terminator and your scope measures across that 50 ohm. The setup should be trx-cable-attenuator-cable-terminator-scope. Offcourse a spectrum analyzer already has a 50 ohm input so it's not needed.

[@karlbesser1696]

@@gartnl True, the impedance of the connected device must be high, otherwise it changes the dummy impedance.

[@KempOutside]

I am totally new to this but want to test my own radios with a TinySA. For testing mobile radios with up to 65 watts output, would a 100 watt 40db attenuator be what I need? Thanks!

[@TheSmokinApe]

Hey Kemp. A few points to note: - 65w is about 48dbm www.everythingrf.com/rf-calculators/watt-to-dbm - a 40db attenuator would take your signal to 8dbm and the most a TinySA can take is 6dbm - The creator of the TinySA has recently stated the for harmonic measurements its best to have an input signal of about -25dbm, so I'd get a 50 + 20db attenuator or a 40 + 30db attenuator and that should get you close enough

[@KempOutside]

@@TheSmokinApe Thanks for the response. So if I understand the math correctly, a 100 watt 40db attenuator on a 65 watt transmitter will drop the power to less than 0.01 watts at 8dbm. So could I use a 10 watt 40db attenuator I already plan to buy for HT testing as the second attenuator? I’m not sure how the two attenuators interact with each other. How do you calculate total attenuation when using multiple attenuators?

[@TheSmokinApe]

@@KempOutside just add them up, so that would be 80db of attenuation. Make sure the one rated for more power is closer to the source (radio)

[@technishn]

The physical size of these attenuators implies that they will get HOT at the rated power, so its best to derate the power rating, significantly, unless aircooled with a fan, especially if long duration tests are made. Commercial attenuators such as by Bird or MiniCircuit Laboratories will be physically larger and much more expensive and probably have some derating. Typically the internals are on a substrate, and can be quite fragile. Another caveat is to keep the connectors CLEAN.

[@TheSmokinApe]

Great comment as always tech!

[@temporarilyoffline]

I swear its not me he's talking about.

[@TheSmokinApe]

Well, you and @k5yvy... After I did the video, I tested my 40db'er and it was off by about 3 db 👀

[@temporarilyoffline]

@@TheSmokinApe they got you too, eh?

[@wiwingmargahayu6831]

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