I've always been under the impression that just because I can recieve strong with an antenna doesn't mean that same antenna will transmit strong. Is this basically correct?
Well, sort of...
Generally you would expect that an antenna that receives strong signals should transmit
You can receive a strong signal but not transmit one under several conditions: perhaps the
most common is when the other station is running a lot more power, or if the SWR on your
antenna is bad enough to cause the transmitter to shut down. There are other quirks that
can cause a difference, too.
Oh, and if you don't have the proper access tone set for the repeater, it won't acknowledge
your signal no matter how strong it is.
If I'm causing a repeater to send a courtesy tone that means I'm reaching the repeater, right?
Yes it does - at least briefly. If your signal is sporatic, or if your power drops rapidly due to
low battery condition, then you can get a tone but not have a good enough signal to maintain
-If I transmit on one radio and monitor with the other, I only get feedback.
The radios are too close to each other, and you are working through a repeater.
If you transmit simplex on one radio you should be able to hear the audio on the other receiver.
But when you transmit on a repeater the strong signal you are transmitting on the input
frequency overloads the other receiver and prevents it from hearing the receiver output
-I whipped up a center fed dipole using 12 gauge solid copper wire. I got the same results, but the j pole is clearly a better antenna because I had way more background noise while receiving.
Not necessarily related.
When receiving a signal on FM, the LESS background noise you hear, the STRONGER the signal is.
Note that the J-pole is prone to common mode RF currents on the outside of the coax, making it part
of the antenna. The dipole can have the same problem, especially if the coax runs parallel to one of
the elements for some distance after it leaves the feedpoint. The coax acting as an antenna does two
things: it tends to pick up more interference from electronic devices it passes between the antenna
and the ham shack, and the radiation from the coax may cause additional lobes and nulls in the
radiation pattern. So, while a J-pole IS simply an end-fed dipole, and should have the same radiation
pattern and gain, installation and implementation differences could cause either to work better in
a specific direction.