Re: Balun question

Pierre,
If you don't remove that 'old' balun, then you don't have a 4:1
conversion anymore, but with 'both' baluns connected, it's more on the
order of an 8:1 conversion. Is that 'bad'? That depends on the
antenna's impedance and the feed line's impedance, but in general, I
would think that it wouldn't exactly be the 'best' thing you could
do. Removing the 'old' balun would probably be your 'best' bet. May
make making connections a little more difficult (or at least
'different') but still the 'best' solution.
Then again, before doing that "out with the old" thingy, try it and
see what the results are with both baluns in-line. Results 'better'
with or without the old balun still in line? Hmm, if I had to
'guess', I'd have to say removing the old balun would probably be your
best bet. At the very least, it means a little less weight hanging on
the antenna, one less 'point of loss' in the whole thing...
- 'Doc

(May not be the 'best' answer in the world, but it's sure a nice
"CYA"... ain't it?;))

.

Relevant Pages

  • Re: loops and 4:1 baluns
    ... A well made balun or RF transformer behaves reasonably well like an ideal transformer, that is, infinite winding inductance, no coupling capacitance, zero leakage inductance, no loss, and so forth, but only under quite a narrow range of circumstances. ... That means the other side of a 4:1 balun has to be terminated with something fairly close to 200 or 12.5 ohms, also resistive, in order for it to work as intended. ... If the impedance differs very much at all from that value, you'll find that the transformation ratio is no longer 4:1, and that the balun will add a series and/or shunt impedance to the circuit. ...
    (rec.radio.amateur.antenna)
  • Re: 4:1 Current Balun Common Mode Impedance?
    ... Then I'm puzzled by your statement that if an antenna is completely symmetrical, no balun is necessary. ... Of course, if you have a symmetrical antenna AND the feedline is placed symmetrically AND you have a truly balanced tuner, then there will be no common mode current and a balun won't do anything. ... there seems to be a pervasive myth that a 4:1 balun or transformer used in an antenna system actually effects a 4:1 impedance transformation. ...
    (rec.radio.amateur.antenna)
  • Re: OCF Sloping Dipole Txmsn Line Input Resistance Measurement
    ... termination of my balanced transmission line to ... 4:1 current balun in my MFJ tuner. ... line impedance needed to transform to a desired impedance. ... You seem to be trying to operate a dipole over multiple bands. ...
    (rec.radio.amateur.antenna)
  • A choke balun is an impedance transformer.
    ... A choke balun can be inserted between a high-Zo balanced transmission ... be wound alongside each other around the core. ... 450 and 600 ohms of the transmission line and the 50 ohms impedance to ... Therefore there is no fixed impedance transformation ratio ...
    (uk.radio.amateur)
  • Re: Fishrod anětennas - transformer and twin-lead
    ... voltage withstand and loss are higher priority. ... obtained by measuring the balun using a VNA, ... that solved the balun + load network for an arbitrary load impedance. ...
    (rec.radio.amateur.antenna)