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Thanks for your comments. You always are spot on. I forgot about
receive when I considered putting the transformer externally.
Still, it is much simpler then tearing everything up. I planned on
doing exactly what you said and try one to test it. As you may
recall, I am waiting for replacement Arduino nano, so I can't do
the work until I get them, and I have some other commitments
that probably will prevent me from testing it until the end of
the month. I don't think the increase in current is a serious
issue, although you never know. The current will increase by 1.4
It seems to me to be the simplest fix. I did the design for 80
meters, and was able to keep the same inductor values. Hopefully
that scales to the other filters, but I didn't do the design for
them yet. Actually the new filter is flatter in the passband
then the original filter.
On 8/11/2018 9:42 PM, ajparent1/KB1GMX wrote:
With all the parallel thread it was somehow missed.
FYI memory says both capacitance and inductance change.
Looking at the idea. I think the basis is sound. It also may
improve the trace
to trace coupling (less coupling). I worry that the increased
highlight other board level RF current loops. The output
to be rewound and that in itself could be an improvement. The ouch
converting back to 50 ohms and in a spot before K3 (TR) to not
Also transformers have loss and bulk.
The current are likely still low enough and the traces may be
light but I think
the worst that can come of it is some unwanted likely small loss.
not burn up but it is always a risk running lower impedance as the
losses go up for conductors. I can't easily evaluate as its RF
effects and wire diameter are are higher and messy to calculate
would have a lot of not validated assumptions. Its faster to test
If someone can try it, they only need to do the 80m filter, wind
to see and test...
I added a image NF1.jpg its a capture from the Rigol on the 6th
blow by of the relays from where the power amp input to the filter
relays to the antenna terminal in receive mode. no relays active.
your seeing going past the 10m filter to the antenna jack via
open TR relay (K3) contacts. The markers in the table are set
3db cutoff or close for a reference point. It translates to if
are perfect the is as good as it gets due to wires and relays.
would I like to see for that case? better than -60db. The only
it gets there is 1mhz (extreme left edge). The source signal is