Knownothing Posted March 16, 2005 Report Share Posted March 16, 2005 I have just build the 4 W FM TX, your notes say T2 will Heat but in my case T2 is cool and T1 She one Hot Puppy what did I do wrong.Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 16, 2005 Report Share Posted March 16, 2005 Hi Knownothing,I guess you built this project:http://www.electronics-lab.com/projects/rf/001/index.htmlSure, it will have temperature problems if its antenna is the wrong impedance or length, or if the whole circuit isn't "aligned" (tuned) properly.Use its minimum supply voltage of 12V and make certain all its tuning parts work to produce a peaked output. If an adjusted part doesn't produce a peak, maybe its coil needs to be stetched or tightened. The output transistor should have thermal grease on it, under its heatsink. Quote Link to comment Share on other sites More sharing options...
Shahriar Posted March 23, 2005 Report Share Posted March 23, 2005 Dear KnownothingI have built the 4watt Tx and it wotks well. the only Transistor that gets hotis TR3 and needs Heatsink.The other Transistor tempreture is normal and is because of the Frequency they are working.But My Tx Problem is that its frequency sometimes changes when I Disconnect the 12V Power supply and connect it again.HTH - Shahriar Quote Link to comment Share on other sites More sharing options...
Platonas Posted March 29, 2005 Report Share Posted March 29, 2005 I had built the cct many many years ago and worked fine.You must check first the 3 resistors if are of the correct value. R3 & R4 are both 10K. In case you made R4 = 1K then Tr1 will overheat. Is R5 = 82 Ohms? You can increase this value up to 120 Ohms without any significant reduction in performance.Check if the transistor oscillates. If not then inspect all the capacitors around it, C5,C7, C15, C6. C7 and C15 are the components that affect oscillation.Last thing, check the pollarity of the transistor, emitter-base-collector.RegardsP. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.