Nice project...I just bit the bullet and picked up a 40dB 100W 4GHz Mini-Circuits attenuator to go along with my 30dB set...don't know why but I always feel apprehensive when hooking up at 100W rig via these things to the front end of my SA and always temporarily insert a 80dB step attenuator on the downstream side and once I'm sure it's "ok" I take that out...but it always give me the heebee-jeebees anyway! Never worry about it when it goes into the service monitor. Keep the project coming! 73 - Dino KL0S
I enjoyed watching this build. I found a 30db 100W same style to make my own. Studying this package type. American Technical Ceramics still makes these. Florida RF gone away, though still coming in via China. Interesting materials science in that these high power resistors use tantalum nitride as the resistive material.
The scope shows that it works, but I don't understand it. Isn't there a direct path, down and back up through the standoffs, and across the aluminum plate from the input to the output? It seems like there should be an insulator between the copper and the aluminum standoffs. Please help me understand why this works. Thanks.
Hi. Can these also be used as a dummy load if one end is switched or terminated to ground? If I want to have a 10x attenuator how would I calculate it using these or similar parts? I wanted to use this style of RF resistor with two leads to build a 2Kw dummy load (by stacking in parallel and in series) but now wondering if I use it as an attenuator to get 10x range on a 1kw s meter going into a 300W dummy load will the 300W dummy load be able to handle 3Kw with a 10x attenuator before a 1Kw power meter. Would a 10x attenuator simply be 1000W of resistance value (marked on the component) at 50 ohms? This seems to simple to be correct.
there are 50ohm load in the same package for sale. here is a small one: th-cam.com/video/4sxPSJKPOs4/w-d-xo.htmlsi=pt9_YO25AHsJIqwS or 250w: th-cam.com/video/tQ381HfpAxM/w-d-xo.htmlsi=3Fx0W9mccAy7f91M 10x is 10dB attenuator attenuators are more complicated than your calculation. th-cam.com/video/VoUaRypDt2Q/w-d-xo.htmlsi=54G2JuwUSTnvSo_n
@@IMSAIGuy The thing is I want to build a 2000W dummy load by using these RFR type resistors but the ones that have two tabs. I'm not sure if they are the same as the attenuator you were using but they look almost the same. The idea is to build a 4x4 or a 3x3 grid to arrive back at 50 Ohms but then I saw the 100 Ohm the 200 Ohm etc and the 500W and even 1000W versions. I found a few deals for around $3 a piece for the RFR 50-250 and I'm just waiting to hear back about a 200-800 I assume it's 200ohms and 800W. The it could be either an attenuator with the bypass or switch one end to ground and use as a dummy load. I'm starting to think an attenuator is better. Then I can use my 1kw and x10 or 20DBi to get 10Kw on the meter and I guess I could still use my 300W dummy load because it would see 10x less power. Is that correct? I will keep looking into it perhaps for the same part you found with that part number or is 1000W of RF resistance equal to a certain amount of attenuation? That's the part I'm a bit confused about. Thanks
@@izzzzzz6 yes, you are very confused. I don't have time to educate you but remember if you attenuate the signal 10x, then 2000W turns in to 200W but the attenuator has to dissipate 1800watts.
Do you have any transmitters to load it with power and test temp rise? I have a 50W one that I'd like to test on TinySA and no attenuator yet. Thinking of building the same thing, but I have doubts that single flange is going to survive all the power without something sophisticated like copper heatsinks and/or water cooling. 250W seems like a theoretical maximum similar to MOSFET datasheet figures. There is also an alternative to spread thermal conductivity across like 10 lower attenuation value flanges, but I expect that so many of them in series would decrease overall +/- db accuracy.
@@IMSAIGuy Hm, ok, if you say so. I knew flange is copper, but heatsink is Al and quite limited in thermal conductivity no matter how big of a thermal mass.
We used Acrian back in the day on Collins radios...I don't know if there around or the present name. Cute 50 ohm resistors..flat supposedly to 1 Ghz. I think their heat sink insulator was BeO...the resistive metal...not sure or don't remember. They know what they were doing and also build UHF and other power transistors... Our buddies at Google...would know
Nice project...I just bit the bullet and picked up a 40dB 100W 4GHz Mini-Circuits attenuator to go along with my 30dB set...don't know why but I always feel apprehensive when hooking up at 100W rig via these things to the front end of my SA and always temporarily insert a 80dB step attenuator on the downstream side and once I'm sure it's "ok" I take that out...but it always give me the heebee-jeebees anyway! Never worry about it when it goes into the service monitor. Keep the project coming! 73 - Dino KL0S
I enjoyed watching this build. I found a 30db 100W same style to make my own. Studying this package type. American Technical Ceramics still makes these. Florida RF gone away, though still coming in via China. Interesting materials science in that these high power resistors use tantalum nitride as the resistive material.
The scope shows that it works, but I don't understand it. Isn't there a direct path, down and back up through the standoffs, and across the aluminum plate from the input to the output? It seems like there should be an insulator between the copper and the aluminum standoffs. Please help me understand why this works. Thanks.
it's a pi attenuator: th-cam.com/video/VoUaRypDt2Q/w-d-xo.htmlsi=iM0q_wCvXlc_0zxo
Hi. Can these also be used as a dummy load if one end is switched or terminated to ground?
If I want to have a 10x attenuator how would I calculate it using these or similar parts?
I wanted to use this style of RF resistor with two leads to build a 2Kw dummy load (by stacking in parallel and in series) but now wondering if I use it as an attenuator to get 10x range on a 1kw s meter going into a 300W dummy load will the 300W dummy load be able to handle 3Kw with a 10x attenuator before a 1Kw power meter.
Would a 10x attenuator simply be 1000W of resistance value (marked on the component) at 50 ohms? This seems to simple to be correct.
there are 50ohm load in the same package for sale.
here is a small one: th-cam.com/video/4sxPSJKPOs4/w-d-xo.htmlsi=pt9_YO25AHsJIqwS
or 250w: th-cam.com/video/tQ381HfpAxM/w-d-xo.htmlsi=3Fx0W9mccAy7f91M
10x is 10dB attenuator
attenuators are more complicated than your calculation. th-cam.com/video/VoUaRypDt2Q/w-d-xo.htmlsi=54G2JuwUSTnvSo_n
@@IMSAIGuy The thing is I want to build a 2000W dummy load by using these RFR type resistors but the ones that have two tabs. I'm not sure if they are the same as the attenuator you were using but they look almost the same. The idea is to build a 4x4 or a 3x3 grid to arrive back at 50 Ohms but then I saw the 100 Ohm the 200 Ohm etc and the 500W and even 1000W versions. I found a few deals for around $3 a piece for the RFR 50-250 and I'm just waiting to hear back about a 200-800 I assume it's 200ohms and 800W. The it could be either an attenuator with the bypass or switch one end to ground and use as a dummy load. I'm starting to think an attenuator is better. Then I can use my 1kw and x10 or 20DBi to get 10Kw on the meter and I guess I could still use my 300W dummy load because it would see 10x less power. Is that correct? I will keep looking into it perhaps for the same part you found with that part number or is 1000W of RF resistance equal to a certain amount of attenuation? That's the part I'm a bit confused about. Thanks
@@izzzzzz6 yes, you are very confused. I don't have time to educate you but remember if you attenuate the signal 10x, then 2000W turns in to 200W but the attenuator has to dissipate 1800watts.
I note the attenuator had input and output flanges marked. Did you pay attention to that? Mark in and out connectors?
Please use N connectors instead of those PL259's !(unless you are planning to use it on HF only)
Based on the frequency range he used when testing it I think that's a safe bet ;)
Do you have any transmitters to load it with power and test temp rise?
I have a 50W one that I'd like to test on TinySA and no attenuator yet. Thinking of building the same thing, but I have doubts that single flange is going to survive all the power without something sophisticated like copper heatsinks and/or water cooling. 250W seems like a theoretical maximum similar to MOSFET datasheet figures.
There is also an alternative to spread thermal conductivity across like 10 lower attenuation value flanges, but I expect that so many of them in series would decrease overall +/- db accuracy.
I only have 100W and it does it easy. the flange is actual copper and about 1/8" thick.
@@IMSAIGuy Hm, ok, if you say so.
I knew flange is copper, but heatsink is Al and quite limited in thermal conductivity no matter how big of a thermal mass.
I know this is an older video, but would there be any value in adding capacitors to block DC? very cool project.
seems dangerous as you have several watts on the other side of that attenuator. it is only 20db
chuck some silver mica's on there or door knobs should be ok
I realize this is an older post but does anyone have a “surplus” source for the rf Florida chip?
Here is a 100W: www.banggood.com/custlink/mKGRjkR3gr
ebay has some
We used Acrian back in the day on Collins radios...I don't know if there around or the present name. Cute 50 ohm resistors..flat supposedly to 1 Ghz. I think their heat sink insulator was BeO...the resistive metal...not sure or don't remember. They know what they were doing and also build UHF and other power transistors...
Our buddies at Google...would know
Can this type attenuator be used in parallel to increase the power handling?
no