Using this calculator https://www.pasternack.com/t-calculator-pi-attn.aspx and my stock of resistors, I settled on a 820 ohm unit to give me something close to 30dB and 50R. Re-testing it shows reasonable flatness +/- a dB up to 500 MHz, then it goes all over the place, dropping to -22dB at 1.5GHz but falling (rising??) to -50dB at 5.8GHz....subject to test equipment vagaries and operator error. At worst I have a 'pair' 100 watt dummy loads accessible from each end....
Gareth
High power attenuator
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radiogareth
- Posts: 1236
- Joined: Wed Jan 06, 2016 9:46 am
Re: High power attenuator
Developing the theme I saw this idea on a Russian MRF300 amp video (144MHz in this case). I did something similar a while back with a 50R thick film resistor on a PC heatsink, with a BNC mounted directly above the socket and it works well.
My question is, is the termination method shown better that a short wire to a BNC in and out socket mounted a few cms away?
I'd guess that as short a lead-in as possible is the best and by using some HD solder tags under the attenuator fixing screws, I can get down to negligible lead lengths using coax flying leads with the braid solder-flooded and secured by the solder tags.
Shorter is better.....?
Thanks
Gareth
- HP_Atten.PNG (904.62 KiB) Viewed 1572 times
I'd guess that as short a lead-in as possible is the best and by using some HD solder tags under the attenuator fixing screws, I can get down to negligible lead lengths using coax flying leads with the braid solder-flooded and secured by the solder tags.
Shorter is better.....?
Thanks
Gareth