Got one of these 100-150w from Floris (radio master) in France. The transistor is blown after several attempts to get it working with a driver I have. I can't find a new one anywhere. Anyone know any other ones I could use in place of it ?

I think the mosfet is one of those new freescale plastic package high gain devices... Has the 'Radiomaster' blacked out the device markings with marker pen? lol

I did see them available somewhere but cant remember where now, think they was about £50.

How did it blow? They are fairly rugged as far as I know...

I think that board has been designed for that device. Transistor says MRF6V2150NB (150w/50v), the best person to contact is Florence directly.

Enigma sell a few of these Freescale Transistors and they're pretty expensive from what I recall.

Yeah and gonna be even more from Florence!

...Probably looking around £50 for a replacement device.

Doesn't look like Engima's got them in but might be worth asking.

http://www.enigma-shop.com/index.php?op ... &Itemid=66

It's a MRF6V2150 if that helps you. When testing if your struggling to get it working run at a lower voltage such as 12v and you should get at least 10-15watts out, at least that way u have low risk of blowing it

Dan wrote:Got one of these 100-150w from Floris (radio master) in France. The transistor is blown after several attempts to get it working with a driver I have. I can't find a new one anywhere. Anyone know any other ones I could use in place of it ?

What happened/ what driver was it? Getting this working should have been fairly straightforward.

Unfortunately when accidents like this happen it's always expensive; a board with just a transistor and a few components may seem overpriced but when you need to buy a new transistor you realise why!
If you do find a new one, make sure you sort the problem which caused the first one to blow before trying it again!

teckniqs wrote:Yeah and gonna be even more from Florence!

...Probably looking around £50 for a replacement device.

Doesn't look like Engima's got them in but might be worth asking.

http://www.enigma-shop.com/index.php?op ... &Itemid=66

You're right, he doesn't have the specific one he needs. The nearest I found is this - http://www.enigma-shop.com/index.php?op ... Itemid=130

I've had dealings with the guy at Enigma and they've been good, so I reckon he'll be able to source the wanted component easily enough.

Mouser sell them $48 each but minimum order 500pcs, they seem hard to get hold of, alibaba have some listed but you don't know if it will a genuine one that turns up from China.

Digi key have them listed £38.48 each

http://www.digikey.co.uk/product-search ... =mrf6v2150

Thanks, it blew from just continuously turning it on and off from me trying to stop it humming. I'll get another driver as I think that is the course of the hum and replace the transistor.

Did you use a regulated psu??
If not that can be the problem of the humming box

Was it humming when hooked up to the dummy load ?

If it was connected to aerial was it humming with no audio connected?

It's important to understand the cause of the hum. Depending on the cause, it may be related to the blown device. If it was simply "RF hum" caused by the audio equipment picking up RF, then it may not be too significant; except it would more than likely mean the testing was on an antenna (which is certainly not to be recommended anyway). If the hum was induced this way, then it might not be directly related, but the device destruction may have been caused by antenna or antenna setup issues. As Teckniqs was getting at, if the hum stops when you disconnect the audio input, it is usually this kind of RF feedback. If the hum is still there when you disconnect the audio input, it could be one of several things. A power supply issue is one; insufficient current capacity / smoothing / regulation (depending what kind of supply). Issues with grounding and / or layout are another, and if you have hum which is caused in this way, it may be causing other issues too; generation of spurii or broadband noise being possibilities, and these types of issue can destroy power transistors very quickly. Another question mark is the driver board itself. I don't think you mentioned what you're using to drive the PA, but if it's going unstable - either because of overall layout / construction, or due to issues of its own, you may be trying to amplify "bad stuff".

Yeh I know testing on a dipole is not recommended but it was all I had at the time. And I was using a jpl995 1w pll board from Jim in Greece. Iv used his boards to amplify before but this one wouldn't stop humming when amplified. Also sometimes it would keep going in and out of pll lock. Tbh iv ditched it now as it was doing my head in lol. Hopefully once I get this new Freescale transistor through it will put out a clean 100w.

Why don't you contact the radiomaster guy ? he should haves somes in stock I guess.

The guy will probably reply back calling him racist [FACE WITH TEARS OF JOY]


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