Zetagi b300p output fault

[Carl]

Hi everyone. I’ve got a Zetagi B300p with an output fault. It works on positions 1 to 4 producing up to 100w on my meter into a dummy load on position 4 of the power selector. Position 5 and 6 are dead with no output at all.
I’ve found a schematic which I have sat and stared vacantly at for a couple of hours but I don’t fully understand the alchemy that goes on in a burner. When I first got it the switch instantly dropped to bits before I could try it. The replacement switch I bought had slightly different pin spacing so I had to oversize the holes slightly in the board to fit it but I’m pretty confident that it is wired correctly. Can just one of the outputs be blown as I kind of expected that if one was blown there would be no output at all?
The preamp doesn’t work either but there are two bc547b trannies that are blown which I’m guessing is the cause of that.
Any help with this would be greatly appreciated.

[Admiral]

Methinks you've answered your own question, check your wiring.

[bigpimp347]

if it works 1 to 4 and not 5 and 6 it's down to the power switch..
it either works of it doesn't, and as you say your get 100w the amp works..
so i'd double check the power switch, there are resistors for each setting, so check they are ok soldered well, then go back to where you fitted it and make sure you have the points in the right place..

[Ashtec]

Yep check them resistors..............

[zephyr]

If you put the switch on position 6 and connect both commons of the switch together, that will give you the maximum power you should get from position number 6, if it works then you have a fault in your wiring.
In position 6 the input power is switched straight through with no resistors in line.
Don't forget to remove the link after you do the test.

[George EI7KO]

I've yet to see one of those that does not give bother. Rare to see one with a working preamplifier either. Deffo suspect wiring. Get yer blow torch back at it lol.

[bigpimp347]

i had a B-300P (yes i know, sorry) in my van and the pre-amp worked..
put it in the house and it didn't

[Carl]

hi. sorry for slow reply, been trying to catch up with the other 5000 jobs im meant to be doing. anyway thanx for all your help, it did turn out to be the switch. physically it looked the correct one but turned out the pins were one position out so position for pin 1 was actually pin 12 on the switch and so on. serves me right for not checking i suppose. so it seems then these things only do about 100w on FM anyway. after i fixed it i was expecting blistering output from the final 2 positions that didnt work before. so the wrong switch must have been giving full power on position 4 instead. is 100w about right then for these things?

[Corblimeyguvnar]

Yep

[George EI7KO]

Rare to see them do any more. A cte 747 is just as good. Pure hype attached to any of that Zetagi stuff. It's budget cb gear pretending to be more than what it is really. Be handy for keeping yer tea warm anyway.

[lambrettadave]

Rare to see them do any more. A cte 747 is just as good. Pure hype attached to any of that Zetagi stuff. It's budget cb gear pretending to be more than what it is really. Be handy for keeping yer tea warm anyway.

last time i tried keeping tea warm on a burner it smashed the cup

[George EI7KO]

Mebbe you should invest in some decent cups then. Lol

[Sniperchaz-001]

Output for B300p should be between 140 and 300w ssb but would register between 70 and 150 on power meter basicaly same reading as AM/FM with 1 to 10w input as sideband your times output by 2 so the 150w becomes 300w after you multiply easy way to remember FM = straight power 100w=100 AM you times by 4 100w = 400w pep ssb be it upper or lower you times by 2 100w=200w thats becouse AM is double sideband and ssb is single sideband FM your useing only 1 part of bandwith to transmit AM your using All four parts of bandwith and ssb your using 2parts of bandwith but your power meter isnt capable of doing the multiplications involved and nearly all manufactures misslead people they dont tell you properly about input power either PEP is where voice peaks in power if you put 10w out on AM into a meter with dummy load and talk your power will go way over 10w probably peaking around 40 if got loud voice even higher with power mic might even drop down cos over driving radio too much audio so if the amp says 10w input pep drop it to 4 or 5w input and it will peak ten watts this is why so many people blow up amps especialy RM or zetagi models they simply do not understand about PEP and the maths involved with AM and ssb if it says 300wssb and meter peaking at 150w its correct reading