Blown up my radio

[tim_ber]

or cooked it.

last night I was saying how great this old radio of mine was as opposed to the new handheld i found onboard, in spite of the strangely mounted aerial.

Well I found another aerial lead which went up the mast.

Radio worked on channel 72 at 1Watt, then tried 25W and worked for a while and then... caput, it now filcks the channel to 16 and the power down to 1 Watt whatever I do.

So always kick down to 1W and channel 16.

Found out the lead did not go to the aerial at the mast head - it came out loose - no wonder I cooked the TX side of things.

Anyone know a website with info about how to fix things (my DIY nature would like to try to fix it - surely it is just a capacitor or something gone?? Rest of radio seems to work)

I have nothing better to do for rest of day or Sunday. Spent most of today googling but no firm answer yet. Can see no physical blown component inside, but don't know whether to look at capacitiors, diodes, resistors or what yet?

thanks in advance for any advice.
have a good weekend
Tim

 

[tim_ber]

Only HALF blown up my radio?

Just thought I'd test the radio on the aerial I know is good and
some good news, the cooking must have cooled off.

Channel 72 stayed on channel 72 at 1W and at 25Watts - neighbours boat picked up transmission.

Well it did, but after a short while it did its usual kick down to Ch16 and 1W thing again.

So to me that means that there is something which is either overheating, (as it has 'cooled' since last night) or something which is breaking down, but regenerating after time (capacitor?)

Am I being logical?

 

[lenseman]

It is possible that the output stage of the transceiver has what is known as a 'directional coupler' such that when you foolishly transmit into an open circuit, the PA stage will shut down. /forums/images/graemlins/confused.gif

If this is the case, you reconnect it to a 'good' antenna, and all will be well. /forums/images/graemlins/ooo.gif

Now, if you have damaged the transmitter circuit, you will need a new Power Amplifier transistor (PA Module). These cost anything up to £70 plus time to fit.

What make, where are you located?

 

[retsina]

If it proves to be an expensive job to repair; consider buying a new radio, at about £85 including DSC

 

[tim_ber]

Oops,
If only it was an ordinary transistor at £0.09. Mind you, I haven't seen anything in there that looks like a transistor (as I know them anyway)

Seavoice RT550, of the Seafarer Range - told you it was old - but not as old as my last one.

 

[lenseman]

Well, if you want to let it 'fetch up' on my (lee) shore, I can take a look at it? /forums/images/graemlins/ooo.gif

 

[tim_ber]

That is a really decent offer, thank you.

Just seen your bio, so if you couldn't fix it then I guess no one could.

To be honest, I don't think the radio is worth it - not even the postage. I've seen one for sale on a local noticeboard for £10.

I do like to learn though - and the look in the case taught me nothing, but I've learnt from you that a whole transistor model exists and is expensive.

Live and learn. Annoyed at my own stupidity - not for the first time.

Thanks again, have a good weekend,
Tim

 

[Cornishmuttley]

I have just had an electrician 'check out' my boat. He went straight to the radio with one of his gizmo boxes and plugged it in to the antenna socket. When he powered it up he frowned and shook his head. "You are using the wrong co-ax do da something" he said. An explanation followed - the gist of which was that because of my incorrect bit of antenna wire, there was about 6 watts of power coming back to the radio from the top of the antenna. So not only was I only putting out 19 watts but I was also potentially doing damage and overheating the radio. But only when I transmitted. As I tend not to waffle this was not a serious problem, but would be if I went on for a bit. Sorry it is a bit long but I hope it helps. The solution for me was to put in a full length of proper co-ax.