Just a few pointers...
bearing in mind the use of ANY amplifier/burner/linear/boots is illegal on UK CB..
Zetagi B300p, this linear is not and never will be 300w..
i have own several or these and their variants, syncron etc..
they say on 4w you get 150w out !! (setting 6)
on 10w you get 150w out.. (settings 1 to 5)
i have never and i mean never got more than 100w using the claimed inputs..
i do how ever run my own B300p with 10w into the 4w input only setting and ONLY get 100w out,(i am a licenced amateur and use 10mtrs mobile). so somewhere the manufacturers have got things wrong and are over claiming..
also bearing in mind they come to the final power on SSB as double the FM power..
this is made up of PEP power, which is peak envalope power..usually made up the easy way as 150w LSB and 150w USB or SSB (USB + LSB) as one unit equals 300w..
so not the maximum and constant power as you would expect, but the most it 'may' reach with the right peaks..
so if you have a B300p you not chatting on SSB doing 300w, you never will be doing that probably around 125w.. which with a PEP value of 250w.
so before you buy, ask if the seller can varifiy the claim stated in the auction, ask if the item has been checked into a 50ohms load, and using a calibrated meter or decent quality meter. this all done and you'll get a genuine reply with a acurate power reading taken.
my advice is never trust the manufacturer, but trust someone who has owned one and had it test correctly..
if you want some serious power get either a quality amateur linear, or go for a CTE internation or a RM/KL make..
these seem to be the more reliable and genuinely quoted amps..
again, 4w is the legal power on UK CB and linears are illegal for CB use.
most linears on here are for CB, but are only legal to use by licenced amateurs on amateur bands..