Hello all
I have a Dummy Load from Welz, specified for DC to 500 MHz with PL-plug. Can I use it also for 2.4 GHz with N-Adapter ? I hope, this is not a dumb question because the 500 MHz.
Tnx & 73
Hello all
I have a Dummy Load from Welz, specified for DC to 500 MHz with PL-plug. Can I use it also for 2.4 GHz with N-Adapter ? I hope, this is not a dumb question because the 500 MHz.
Tnx & 73
Hi,
I think 500 MHz is far away than 2.4 GHz.
Which power you plan to use ?
The reason the dummy-load is spec'd up to 500 MHz is that the construction adds capacitance and inductance whose influence gets bigger with higher frequency.
Without measurements it is hard to define what the actual deviation of the dummy-load is.
But, you can also use the high frequency to your advantage. Some types of coax cable (think RG58) have a "high loss" on high frequencies. By connecting the dummyload via a long length of RG58, part of the power is dissipated (lost) in the coax and if you use the 500 Mhz dummy-load to terminate the cable then reflections from the dummy-load are also attenuated by the same lossy cable.
Kusch doesn't specify RG58 on 13cm but on 23cm they list 64 dB per 100m. Extrapolating 23->13cm should be another 15 dB. Practially, 10m cable would yield roughly 8dB.
In short, if you use a long run of crappy coax (the crappier the better!) to connect your dummy you will probably be fine. Note that cable loss is dissipated, so don't wind the cable, run it loose over the floor.
No
Hello all
I have a Dummy Load from Welz, specified for DC to 500 MHz with PL-plug. Can I use it also for 2.4 GHz with N-Adapter ? I hope, this is not a dumb question because the 500 MHz.
Tnx & 73
You can't. Even the 500MHz rating is doubtful with a PL259. They are just resistors in a tube. Not good to 2.4 GHz.
If that's all you want to do, just buy or find a long length of coaxial cable. At 2.4 GHz the loss of RG58 is 1 dB per metre and RG213 0.5 dB per metre. To get a 20 dB or better return loss you only need 10m of RG213 as the loss count's twice. Perhaps you could connect to your HF antenna coaxial feeder?
This is why it is not a good idea to have a long run of RG213 to feed your 2.4 GHz dish. Use something better, e,g, Heliax.
Mike
Hallo,
in combination with a S-Band-dummy load, the return loss at 2,4 GHz is interesting. I am looking for a wide band wheatstone bridge. The usual bridges don't work exactly at 2,4 GHz because of incorrect impedance situations and unsuitable baluns. Commercial bridges don't fit with the amateur budget. A directional coupler gives up to 30 dB dynamic range between open and load, a resistive bridge probably would perform better, I think.
Any ideas ? Thanks in advance.
73s
Andreas
For those looking to build a directional coupler, have a look at Paul Wade's article:
Hallo,
the text from W1GHZ is interesting. 21,4 dB directivity at 2,4 GHz isn't too much.
I own a chinese directional coupler. But I think, a well designed bridge will perform better. R&S and Wiltron can do. May be a strictly coax design with good grounded semirigid cables and the right balun will give enough performance. The only way to find it out is doing....
73s
Andreas