...The panel has a single needle meter that says "RF Reflected Power" with 2 scales - one that goes to 200 and one to 2000.
So there are two ranges for FORWARD power and one for reflected power.
The 1 page instruction manual that comes with it describes operation of the tuner as follows:
Operation:Now for my questions!
1. Set transmitter matching and antenna matching controls to 50.
2. Listen on receiver for maximum band noise while turning roller inductor for maximum noise.
Caution: Do not turn counter below 00.00 or exceed 36.00 or serious damage may result to the roller inductor.
3.Appy enough power to the system to get a reading on the meter in the reflected position
4. Rotate the roller inductor for a drop in reflected power reading.
5. Adjust "transmitter matching" and "antenna matching" controls for a minimum reading of reflected power.
1) What is "maximum band noise"? Static? I gave up on trying to tell a difference on this step and went to step 3 instead.
The general back ground noise - could be signals or whatever else you hear in the receiver.
Sometimes this has a sharp peak, sometimes it doesn't. With some antennas I can pretty
much tune my tuner using this alone. But it may be more abrupt tuning a capacitor than
with a roller inductor, which requires more time to move from one end of the range to the
You don't have to do this step - it just helps you get close to the final setting.
2) ...Then I made the mistake of reading more on these forums... From what I read and understand, there is no way I should be able to operate on 20m with a 40m dipole, even with an antenna match... so why did it work? Did I hurt the transceiver in the process?
You didn't hurt the transceiver. And, yes, it does work, just not very efficiently.
There are a lot of details to the answers in these forums. Sometimes hams remember
to state the conditions and assumptions, sometimes they don't. Rarely is there
a clear, unambiguous answer "yes it works" or "no it doesn't", rather there is a range
of how well
it works, and whether there is a better option.
In the case of using a 40m dipole on 20m, I've done that, too. Or maybe it was working
40m DX on an 80m dipole running QRP. It certainly wasn't optimum, but it made contacts.
In your case, we can guess that the impedance of the 40m dipole used on 20m is around
2000 ohms (SWR = 40 : 1). If we plug that into VK1OD's transmission line loss calculator
) for 100' of RG-8X (Belden 9258) it predicts a
loss of 7.9dB, so about 16% of your power reaches the antenna. If you are running 100W,
about 16 watts get radiated.
That's not very good for efficiency. With a proper match you'd have 78 watts radiated
instead (due to the 1dB loss in the coax when matched.) But I make lots of contacts
running 5 watts, and you're still stronger than that. With good conditions it is still
enough to work around the world - but you wouldn't need the conditions to be quite
as good if you didn't have the the extra feedline loss.
3) Should I buy a separate SWR meter to use with this tuner? If not, what is the advantage of having one?
As long a the built-in meter is adequate to tune the antenna, you don't need
Sometimes it is useful to measure the SWR without the tuner in the line - for example,
you should be able to run the 40m dipole straight into the rig on 40m without any tuner.
In that case a separate SWR meter may be useful.