Changing the antenna input impedance DX-440
- Thanks Bob and Andy for your last posts. (Zener diode & the DOS inductance calc). I typed a reply that day, but apparently Yahoo had a seizure & it never went through. But thanks, both of those will be useful.
For now I've decided to order more Flex-weave wire, to add many more turns to my large longwave receiving loop. I sort of feel like a fool for 'downgrading' to a single-turn like I had. But, would you believe that, the other night, I got a 36 mile-per-watt beacon catch on that, on the DX-440? A 25 watt beacon 900 mi from here.
I have another question that you may be able to help with:
The DX-440's antenna input jack is 75-ohm I believe. Or 50-ohm; either way its low impedance. IF I were to simply bypass that jack internally, would that alone give my a Hi-Z connection?
- It's good that you're stirring-up hornets, Bob. I experiment a lot on my
own, but you & Andy give some really valuable insight. I appreciate it.
I finally got my 'extra' wire, increasing the windings on my large loop.
(See pictures section of this group for view of the loop). From 1 winding
to, now, 4 winds. This gives a calculated inductance of 82.8 uH. Well, my
HF utility reception is fantastic! RAF in England no problem. Also I can
better copy 60 WWVB and 100 LORAN. - Keep in mind I have an LF upconverter
for these low frequencies - So the extra windings really boosted 10-100
kHz and 530-20000 kHz. BUT the strange thing is, my 'middle' reception has
taken a dive. That is, I'm getting worse reception from 100-530 kHz. Which
is my area of interest.
I THINK I need to get lower-value caps for 100-530 kHz, because my
inductance has now increased 8x. But still, if that was the case, I don't
understand why the really low stuff (60 & 100 kHz) has improved.
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