I didn't think from the original post that this was going to be used as
transmission line.
I pictured simply tying both sides of the speaker wire to one terminal
on the UN-UN.
Speaker wire because he has it, vs. buying wire specifically for a
temporary antenna.
"Random wire" so the 9:1 transformer is needed if it's close to a
resonant length and he's feeding the end, maybe not if the wire is some
non-resonant length, like 53 feet or so.
73 -- Lynn
On 12/17/2018 11:58 AM, Jim Brown wrote:
On 12/17/2018 6:45 AM, Don Wilhelm wrote:
However, if you are using the speaker wire as a transmission line, it
has relatively high loss characteristics
Compared to what? So-called speaker wire (which is really lousy for
speakers because it should be twisted pair to minimize RFI) has Zo in
the range of 75-100 ohms. Unless it's wet, virtually all the loss in
transmission lines below about 100 MHz is due to wire resistance, not
dielectric loss. There is, of course, additional loss due to any
mismatch that may be present, but that still comes down to loss in the
resistance of the line. While I haven't measured any zip cord, I've
measured a lot of closely spaced parallel wire transmission line made
from THHN, enameled copper, and Teflon insulated #12 silver-coated
copper. In order of loss at dB/100 ft at 10 MHz from low to high, the
Teflon #12 is lowest at 0.94dB, then RG400 at 1.22 dB (about the same as
RG58), then #12 THHN at 1.34 dB. #12 or #10 enameled copper had the
greatest loss, 2.4 dB/100 ft.
73, Jim K9YC
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