Check every X seconds if a "nick" is on my channel

I need to check every 10 seconds if a user with the nickname "Megatron" is connected on #mychannel
I've tried with this code but does not work

Code:

/timer 0 10 /checkadmins #mychannel

and

Code:

alias checkadmins {
  if (Megatron ison $chan) {
    /part
    /timer 1 300 /join #mychannel
  }
}

Thank u guys

the second code should be:

Code:

alias checkadmins {
  if (Megatron ison $1) {
    /part $1
    /timer 1 300 /join $1
  }
}

as you want to pass '#mychannel' into the alias as the first variable used.

It works perfectly, thank you so much!!!!