Check RD30HVF1

[Sietedj]

Hello, a couple of days added a small power supply for the fans, who did a tarball noise and it was the only way to remove ago. The fact is that after the transmitter no longer worked. I have not touched anything else and it was working well, do not know why this has happened.
I wanted to know if you can check the status transistor soldier on the printed circuit, or no check out of it. I suppose that besides the RD30, take another transistor but do not know what is, if it could be this that does not work. Power is something, about 2 or 3 W by the distance to come, but the ammeter does not reach 0.5 ampere consumption when before had 3A. I have some doubts but I ire more slowly to not extend this far.
Thanks in advance!!!

[Sietedj]

This is the transmitter.
Well not let me add photos
It is the model 30w http://www.hf-electronics.nl

[s2000]

Hi Sietedj, there is a simple test you can do on rf mosfets...



It's possible to test with the transistor in situ, but you would probably have to desolder the surrounding components from the mosfet in order to get the test to work.

If you do have to change it, I would recommend you get an anti static wrist band too, as static can zap a mosfet

[Sietedj]

S2000 Hello, thanks for the info, I had already seen this video. I have antistatic wrist strap, would serve him against discharge the water faucet in the house?

[Sietedj]

S2000 Hello, thanks for the info, I had already seen this video. I do not have antistatic wrist strap, would serve him against discharge the water faucet in the house?

I have seen on Ebay for 14,20$ http://www.ebay.es/itm/1PCS-RF-VHF-UHF- ... SwgY9Xefsy

how I can know if it is false? I have also seen enigma-shop for 14libras plus shipping, I guess here is legit, right?

[Albert H]

Do NOT buy anything from "Polida" on Ebay. They have been reported for false advertising and fake parts many times. They get closed down by Ebay regularly, then spring up under a slightly different name (usually the year changes!).

Don't waste your money with these people!

[sinus trouble]

WAIT!!!! Slowdown and think about what youve actually done in a calm and logical way! Ive seen soo many people jump to conclusions and mess up!!
You say that you have modified the PSU in some way? the problem seems to be there?
You need to check that it is functioning correctly first before you start blowing new components!
I may be a lucky git? but ive never had any trouble with fans? If the PSU has plenty of guts, grounded properly and well away from audio sources? it shouldnt be an issue!

[Sietedj]

Do NOT buy anything from "Polida" on Ebay. They have been reported for false advertising and fake parts many times. They get closed down by Ebay regularly, then spring up under a slightly different name (usually the year changes!).

Don't waste your money with these people!

Thanks for the warning Albert H. I recommend buying Enigma-shop?

[Sietedj]

WAIT!!!! Slowdown and think about what youve actually done in a calm and logical way! Ive seen soo many people jump to conclusions and mess up!!
You say that you have modified the PSU in some way? the problem seems to be there?
You need to check that it is functioning correctly first before you start blowing new components!
I may be a lucky git? but ive never had any trouble with fans? If the PSU has plenty of guts, grounded properly and well away from audio sources? it shouldnt be an issue!

Hi, I have not changed anything, just remove the fan cables from the main source to another smaller to avoid noise. The noise is not appreciated just, only when there is no music and very loud volume but preferred to sound cleaner. The noise problem is because I do not know if the power supply is not very good and not well filtered. I'll check with another power supply more quality to see what happens.

[Analyser]

Do NOT buy anything from "Polida" on Ebay. They have been reported for false advertising and fake parts many times. They get closed down by Ebay regularly, then spring up under a slightly different name (usually the year changes!).

Don't waste your money with these people!

Thanks for the warning Albert H. I recommend buying Enigma-shop?

Yes, Enigma shop are fine.

[shuffy]

+1. You get what you pay for. Never had a problem, and the customer service is excellent.

[Sietedj]

Well, I tested the transmitter with an external source of quality and does not work. I unsoldered transistor to check and is broken. So I buy a wrist strap for next time, I guess one of these cheap selling on Ebay for 2 € will be enough, right?
The transistor buy it in Enigma-shop is the best price we've seen.
Thanks for the help!!

[Sietedj]

I have already received the transistor enigma-shop, it is up and running !!!

[Sietedj]

Hello, I did not last even a week transistor, it has broken again. This time been without touching anything. Anyone would think that might be?
https://www.dropbox.com/s/7pjj62slsx5th ... a.jpg?dl=0
In the picture, where it says power is really adjust to adjust the power or bias?
In http://www.hf-electronics.nl they said it was to adjust from 0 to 30W.

[s2000]

Hi there Sietedj, I am not familiar with that model but from looking at the photo, the pot marked "power adjust" will be to change the bias to the RD30HVF1 but depending on what you set it at will change the power too. From looking at the datasheet, you would set that so the RD30HVF1 is drawing 0.5A quiescent current (Idq). You would usually do that with no rf input present so would need to disable the incoming rf to the main amplifier.

Seems strange it has blown again. It looks like a good transmitter and has swr protection built in. You haven't changed the swr pot since you bought it? It would have a specific setting based on what swr level you want it to cut out at.

Also what about your power supply? Have you tested the output voltage? Sometimes a supply can go faulty and put out too much voltage. This can kill an rf device.

[Sietedj]

Hello S2000, on setting SWR I have not touched anything besides I have 0 in the external meter. The power supply which is sold in China, cheap. 8A is 13V and I have measured and is stable at 13V.
When I bought it is assumed that the power was adjustable from 0 to 30W and the only thing to regulate is that pot. If I put the low minimum power and climb as it goes up.
If it is as you say and I have to adjust to 0.5A and disconnect the rf I will be complicated for me.

[s2000]

Well usually you would set the device based on the datasheet but it does also depend on the level of rf drive that the stage before is giving.

I am just wondering, when you changed the mosfet over to the new one from Enigma, did you put heat transfer compound onto the new device?

[Sietedj]

Yes, I put heat transfer compound. The transistor temperature was less than 40 degrees. I'll have to learn how to remove the RF signal and adjust to 0.5A.

[Analyser]

There's a few things to consider here....

1. Could the RF transistor be getting too hot? Is it mounted correctly and some cool air blowing over the heatstink?

2. Did you make an adjustment to the power (bias) pot? Although you can make power changes to an amplifier using the bias control it can be easy to bias too much and blow the device that way. These modern RF transistors have much better matching between batches but still the circuit needs to be designed and adjusted carefully to avoid accidents.

3. Are you running the amp in to an aerial or dummy load? If you're using a dummy load then the problem is over voltage on the power supply, too much bias or overheating.
If you're using an antenna there may be a fault with the antenna (loose/ intermittent connection) or excessive SWR. Although SWR protection circuits normally catch antenna issues they aren't perfect; I've seen many transmitters with SWR protection and blown output transistors, in fact I have a professional 1KW CTE amplifier currently in the workshop for repair which has 4 x BLF278 transistors all blown. This has comprehensive voltage/ SWR/ thermal protection so in theory should be very hard to break. Sometimes antennas can receive a discharge from the atmosphere (static/ lightning) which can go back down the coax and blow the transistor.

[Sietedj]

Hi Analyser,
The transistor is on heat sink, a fan and the temperature was below 40 degrees.
Today it rained but it has not been an electrical storm, I had transmitters running storms and nothing ever happened to me. I use an antenna on the roof. The SWR is correct, it is 0.Now I have another transmitter 6W working perfectly with the antenna.
I understand that it may be by adjusting the bias, but I thought that this adjustment was to vary the power from 0 to 30W which is what I thought. I ask where I bought the transmitter to see they tell me.