Re: RF power chain mods and improvements..
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I didn¡¯t say there would be a lot of power, but it does work¡ and the most obvious answer is a fifth filter.
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Dr. William J. Schmidt - K9HZ
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From: [email protected] [mailto:[email protected]] On Behalf Of ajparent1/KB1GMX
Sent: Monday, May 28, 2018 12:35 PM
To: [email protected]
Subject: Re: [BITX20] RF power chain mods and improvements..
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Ralph,
Ok 13.8V at 3A (allow about 450 for the relays and all) is 41W in and 16 out and that means
the rest is heat in the finals.? That efficiency is way low blow 35%.? For a push pull at HF
45% is the bottom (start looking for reasons) as id expect about 55%.? ?Granted it can vary
with frequency but usually it decreases with higher frequency.
The output transformer may be either not enough inductance, turns or wrong ratio.
you say your using IFR1200?? IFS that a service monitor.
William,
If I see power at 6M there is a problem!? ?Translation is that at 6M i'd expect the output
to be at least 30db down from 10M or the low pass filter is very broken.? Also the low pass
filter L1-L4 with associated caps is not working as the cutoff is around 35mhz.
The problem is with only 4 filters what cutoff frequencies can you use that allow sufficient
second and third harmonic suppression that includes 6M?? And Meet the VHF requirements..
Doing 6M with only 4 filters pretty much means giving up bands and likely then other issues?
come to the forefront.
Allison
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K9HZ
