When I picked up the PM2B mentioned in #3, there were two 30MHz low pass filters included in the price.
Further, I had some older low pass filters, a 30MHz and a 50MHz one, so I got them all tested today:
Out came the NanoVNA F (4" screen). The tests were made with a wideband calibration setting, so the absolute values are not perfect.
All filters are in good working order.
This means that I now have three 30MHz low pass filters and a 50MHz filter, all fully functional:
The old one I have is a Yaesu filter with a 100W rating. I have had that for decades.
The second one is a Trio/Kenwood filter, 100W rating.
The third one was a bit of a surprise. An old Drake filter rated 1000W.
The fourth one is a BNOS low pass filter for 50MHz. No rating on the filter, but I suspect it is 10W or so. It is a much smaller filter than all the others.
I reckon that all those ratings will be reduced to about 50% of the stated rating if I want to operate 100% duty cycle modes, like digital modes, e.g. FT8.
I opened the 1kW filter, and all looks clean, a beautiful mechanical construction with silver plated coils and high power capacitors, likely silver mica types. Somewhere I have a PA for 10-11m that I suspect has poor harmonic suppression so the 1kW rated filter would likely fit nicely in a system with that one - if it has sufficient linearity for SSB. OK, as I mainly want to use it for CW that is not so much of a problem. FSK digital modes will also work nicely.
The other option would be using this filter with an old IC-M710 that can deliver 150W continuously.
I would hesitate to use this filter with my 1kW power amplifier, even if I use it extremely rarely.
Given that I paid <$100 for the two filters, including the 1kW one, as well as the not fully functional PM2B, I consider this trade as excellent.
I picked up more at that rally, more about that later, as it is a different story.
No comments:
Post a Comment