No one can hear me.

[WRTH755]

I have a radioditty GMRS radio.  Only once when I was hiking could someone hear me who was over 50 miles away.  Since that day, I hear people on channels clearly but ask for a sound check.  No one can hear me at all.  What do I need to do?  Thank you.

[SteveShannon]

8 minutes ago, WRTH755 said:

I have a radioditty GMRS radio.  Only once when I was hiking could someone hear me who was over 50 miles away.  Since that day, I hear people on channels clearly but ask for a sound check.  No one can hear me at all.  What do I need to do?  Thank you.

If you were using a handheld you should not expect that people can hear you at a distance of 50 miles.  
It’s not unusual to be able to receive farther than a handheld can transmit. 
There’s no secret to range: height, good antenna, line of sight, and power. 

[PRadio]

24 minutes ago, WRTH755 said:

I have a radioditty GMRS radio.  Only once when I was hiking could someone hear me who was over 50 miles away.  Since that day, I hear people on channels clearly but ask for a sound check.  No one can hear me at all.  What do I need to do?  Thank you.

They may be using a "privacy" tone so they won't hear anyone not transmitting with that tone. 

[SteveShannon]

16 minutes ago, PRadio said:

They may be using a "privacy" tone so they won't hear anyone not transmitting with that tone. 

Good point. 

[wayoverthere]

One other idea that comes to mind is what channels this is occurring on.  The usual 15-22 (462.575 through .725) are shared between simplex and repeater outputs. One easy reason to be able to hear them at that distance is if you're hearing them via a repeater. To talk back to them through the repeater, you'd need to use a channel set with the appropriate offset and tone for that repeater.