to add to the confusion
There are a number of likely causes and the most probable is a bad coax connection someplace bewteen the antenna base and radio. If you have any of those cheap solderless connections, they are notoriously bad to begin with and only get worse with age.It could be the radio itself but as most of the circuitry for the transmitter portion is common with the receiver side except for the amp transistor(s) so the radio is typically the last cause if you are able to receive properly.As someone said, it's easier for the radio to receive with a bad connection than it is to transmit a proper signal. Most contemporary VHF radios are internally protected from coax shorts such that they essentially shut down the output power if a short or high SWR is detected. Unfortunately, using an SWR meter to detect a coax problem can be very misleading. It can tell if there is a problem but a low (good) SWR isn't a good indicator of proper coax and antenna efficacy. Exageration for effect - if you connected your coax to a lightbulb, the SWR would be excellent, however, nobody would hear your signal so beware of simple recommendations.Check and replace any questionable connections with good quality soldered coax connectors and your problem will probably go away.Don