On 11-Nov-17 9:33 AM, Jim Thomson wrote:
## My array solutions Powermaster 20 kw coupler works from 500 khz to 30
mhz. Apparently it works quite well for
AM broadcast purposes. The AS 10 kw coupler works from 1.8 to 60 mhz... and
ditto with the AS 3 kw coupler, same deal,
1.8 to 60 mhz.
My PowerMaster 3 KW coupler let out all the magic smoke after a couple
minutes of 400W on 475 kHz. I didn't bother to try the 10 kW coupler.
Before the smoke appeared, it was reading the correct power and SWR.
Forensic analysis proved that the "voltage" sense torroid had too little
inductance to work at that low frequency. In fact I am amazed it doesn't
burn up on 160 m!
I reverse engineered the coupler and built a new one with different core
material and now it work great on both 475 and 137.
73, Larry - W7IUV / WH2XGP
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