[AMRadio] My BA Station: HQ-170 and Globe Champ 350


ne1s at securespeed.us ne1s at securespeed.us
Mon Dec 12 08:23:20 EST 2011


> One item I made for the Champ is a 4:1 transmission line transformer so
> the rig always works into 200 ohms. It's not a balun, but a un-un out pf
> Sevick's book. I have resonant antennas for the CW portions but have a
> tuner for the rest, so the transformer will never see anything far from a
> 50 ohm load.
>
> I did this because 50 ohms is the minimum the Champ's output tank can
> match and it won't go nearly that low on 160 m. This way, I can use a
> single feed line and never worry about running against the limit of the
> output network. I also made a 2:1 transformer, but that yields the minimum
> impedance for 160 m. I tested both and, while both work fine, the 4:1 puts
> me closer to the middle of the tank's range on all bands. Everything is
> certainly happy at 200 ohms.
>

Great idea. Some of the Johnson gear I have (Viking I, Ranger) doesn't
like 50 ohms on 160M and 80M, and the plate current runs too high, so I
de-tune the antennas slightly to make the rigs happy. (I use tuned feeders
for those bands anyway). But if you use coax-fed antennas on those bands,
that isn't an option.

73,
-Larry/NE1S



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