Vastelec 1W FM transmitter problem

[Kim-DK]

Hi,

My primary FM transmitter (1W) has suddenly got very reduced range.

Last year the range was more than 1 mile (open air) Now, with the same powersupply, cable and antenna, its down to less than half a mile!

Sound quality is´still fine and RDS (minirds) works

I fear that the output power transistor has blown.

Does anyone know what type it is. Mine has no writing on it!

Regards
Kim / Denmark

[eswets]

check the level of the audio supply. When testing mine, if I lowered the volume on my ipod the signal got weak but if I raised the volume it got better. When I went full volume the signal was the strongest and lots of hum. I'm not an FM guy but try that.

[XmasInGalt]

I have the same transmitter and it started acting the same way. At first, the transmitting distance would be fine then the next minute I had to be within 5 feet of it to get a clear signal. Thought I had a problem with the antenna connection but nothing fixed the problem. I had a Hlly transmitter as a stand-by that I used in 2008. After Christmas, I purchased the EDM LCD unit which I'm very happy with. I just wish I had waited until they had the EDM-LCD-RDS unit. I did mod the unit with a PIRA mini-RDS and it works. Just like the idea of a complete package. I think I'll pull the Vastelec out again and give it some proper tests. Like you, I'm also concerned that I killed the power transister. If I make any headway on figuring out what's wrong with mine, I'll post it here.

[budude]

Do you have a pointer to the RDS conversion for the EDM-LCD? I have the same unit and would like to add that.

Brian

[Kim-DK]

I have the same transmitter and it started acting the same way. At first, the transmitting distance would be fine then the next minute I had to be within 5 feet of it to get a clear signal. Thought I had a problem with the antenna connection but nothing fixed the problem. I had a Hlly transmitter as a stand-by that I used in 2008. After Christmas, I purchased the EDM LCD unit which I'm very happy with. I just wish I had waited until they had the EDM-LCD-RDS unit. I did mod the unit with a PIRA mini-RDS and it works. Just like the idea of a complete package. I think I'll pull the Vastelec out again and give it some proper tests. Like you, I'm also concerned that I killed the power transister. If I make any headway on figuring out what's wrong with mine, I'll post it here.

Hi,

If you remove the cooling star, does the transistor have anything written on it?

Regards
Kim

[XmasInGalt]

Do you have a pointer to the RDS conversion for the EDM-LCD? I have the same unit and would like to add that.

Brian

This is the thread that I followed to add RDS to my EDM transmitter.
http://doityourselfchristmas.com/forums/showthread.php?t=4170

[XmasInGalt]

Hi,

If you remove the cooling star, does the transistor have anything written on it?

Regards
Kim

I removed the heatsink and the only writing I saw on it was the word 'Korea'. No other markings. I'm going to attempt to test it this weekend and see what I can see.