Hello Chris,
probably the other LFers are around to have a fresh bier :-) today
here +40°C...
I don't know (or remember..) which kind of antenna are
you using: how much the impedance changes with the other conditions
have you huge change of impedance? have you a variometer in place?
In my case from rainy to dry weather I have more detuning than change
of impedance and the variometer is enough for these adjuments. I have
also a separation/matching transformer in line but it was adjusted
after resonating the antenna (it matches the few tens of ohms to 50
ohms value).
If you need really to match the impedance you could install a
transformer with more taps, but remember to not switch during
transmission!! my matching separating transformer is made on 2 stacked
FT240-43 cores with 20 turns on the 50 ohm side.
Marco, IK1HSS
----Messaggio originale----
Da: [email protected]
Data: 23-giu-2017 14.03
A: <[email protected]>
Ogg: LF: Transformer questions.
Hello LF'ers,
Two 500 watt Class D amps combined. The output transformer of the
combiner is now an auto transformer. This feeds, via RG-213 to
outdoors, where an isolating transformer, that is a conventional
primary / secondary transformer with taps for impedance matching then
feeds my loading coil and then the antenna. Can I wind the isolating
transformer as a 1 : 1 and do impedance matching (which changes with
weather / foliage growth) indoors using a tapped combiner auto
transformer? I want to change the impedance matching / isolating
transformer anyway as it runs a bit hot on long TX sequences. I tried
an auto trans former as the impedance matching one outside, but had
serious RF into the mains causing various issues, a conventional
isolating / impedance transformer fixed all that, so I assume it needs
to stay, even as a 1 :1 ? Thanks.
--
Best regards,
Chris mailto:[email protected]
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