Please Help!!

[selldoor]

Re: Please Help!!

Well it seems like it is either the power jack or the switch - suggest you resolder both.

[budm]

Re: Please Help!!

Look real close at the power switch then, you should be able to jump the connections at the power switch to see if it will come on.

[StevieG]

Re: Please Help!!

Look real close at the power switch then, you should be able to jump the connections at the power switch to see if it will come on.

got it all powering up. but not giving enough power out like it used to. it used to reach 15 miles but now it just abouts gets upstairs. i don't know what else to do.

[budm]

Re: Please Help!!

I hope your buudy did not change any tunning cap setting, trimpot setting, etc.
Do you have owner manual and equipment to make an adjustment?
I see about 6 tuning caps, some pots, some adjustable tuning coils.

[StevieG]

Re: Please Help!!

I hope your buudy did not change any tunning cap setting, trimpot setting, etc.
Do you have owner manual and equipment to make an adjustment?
I see about 6 tuning caps, some pots, some adjustable tuning coils.

No he never touch any of the settings.
is that rf resistor meant to get red hot ?
i warned him not to touch any of them setting on the caps. they are all where the should be.

[budm]

Re: Please Help!!

Nothing should be getting red hot on the board.
Where is that located on the board?

[StevieG]

Re: Please Help!!

thats the part you showed me where it went and how to solder it.
its that hot it burnt my hand lol

that black resistor at the top right gets red hot.

[Mad_Professor]

Re: Please Help!!

thats the part you showed me where it went and how to solder it.
its that hot it burnt my hand lol

that black resistor at the top right gets red hot.

What resistor?

I see a transistor and acouple of diodes.

[budm]

Re: Please Help!!

You mean the MOSFET (the 3-leg device)?. If it runs hot that means it not switching, but it stuck in the full on mode.

[StevieG]

Re: Please Help!!

You mean the MOSFET (the 3-leg device)?. If it runs hot that means it not switching, but it stuck in the full on mode.

yeah thats the one what gets hot the MOSFET.
dose that mean i need to get another one ?

[selldoor]

Re: Please Help!!

Can you show us how you have connected the wires up - did you resolder
the connector and switch so it is now wired correctly?
When it is in its case does the Transistor/Mosfet get fastened to a metal bar? or just stand on its own.
When referring to parts please use the board description L3 C15 and so on
and if in doubt mark them on a picture.

[kc8adu]

Re: Please Help!!

it would help to know what this unit this is.i often dont even look at "please help me!" posts.
put the brand and model in the subject!youur post might get noticed by someone who knows that unit.
methinks its a pirate fm transmitter.

[StevieG]

Re: Please Help!!

it would help to know what this unit this is.i often dont even look at "please help me!" posts.
put the brand and model in the subject!youur post might get noticed by someone who knows that unit.
methinks its a pirate fm transmitter.

All i know its a 18w fm transmitter ;-)

[budm]

Re: Please Help!!

If it is 18Watts transmitter, then that MOSFET for the final stage drive should be mounted on the heat sink. Is the antenna OK, no short and proeprly tuned for lowest SWR (Standing Wave Ratio)? I still wonder how you calibrated and tuned this unit.

[StevieG]

Re: Please Help!!

ive screwed that mosfet to the side of the aluminum case as it should be. but im not getting the power it should be giving. i can just about get the signal upstairs on a fm radio. the transmitter is pll digital display. you tune it by using the up and down buttons as shown in picture.
as i don't know anything about electronics. maybe best to just get another one off ebay.

[budm]

Re: Please Help!!

I cannot see how it is tuned by just pushing the button since there are so many trim caps, coils, potentiometers that have to be maually adjusted by hands.
It must have real big power supply to be able to get that MOSFET REDHOT, it is the biggest load in the whole circuits! I would think the power supply would have shutdown or blow the fuse.
At this point you may be better off getting the new board, and hoefully it is properly tuned and adjusted so it will not take out the MOSFET due to poor SWR.

[StevieG]

Re: Please Help!!

All them trim caps are soldered to the screws etc. so theres no way of moving them thats all done by the company who make them. its only 12v dc power supply im using. i think there must be a break on the board somewhere. i touched that MOSFET and it was that hot it left a blister on my finger lol. to buy a new board would cost £70 so i might as well just get a new rig for that price.