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Upgrade to V3. It sorts all these problems. - f

Thanks. ?This is what I was looking for. -- Bob AA4FJ

Ashhar, can I first of all congratulate you on all the work on the sbitx V2 and V3. This new V3 I have upgraded to is superb and has gone well above all my expectations. It must surely has made the

Farhan; I switched out the silpads in my DE for Alumina Ceramic insulators. The attached thermal image photos show the stock silpad under the right FET and an Alumina Ceramic insulator under the left

Gordon, I failed to mention but I have tried it with Aluminium Nitride, Silpads (Grey and Blue) and Mica insulators, there was no difference at all. I should get a contact sensor to measure the rise

It would be interesting to see if the drop in power is reduced with aluminum nitride insulators. Previous work has suggested it will decrease the rise in temperature of the die For a very

The following files and folders have been uploaded to the Files area of the [email protected] group. * /SBITX KB1GMX-mods ideas./Bias Circuit for LDMOS Amplifiers.pdf (

I put a copy of the full article in the files area under my call. -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.

Farhan, You didn't specify where or details.? This is the revised sBitx or some proto? What the bias when cold and after immediately after a keydown session? While my amps do not exhibit this,

DJ9BFC, Yes it could and no not in that circuit.? However to get the needed thermal coefficient it needs to be two diodes in series. The npn is a 2n3904 that is mounted on the heatsink near the

Make sure meter is set to “peak” power, not average power. bob wd8lic

why is there an npn transistor used as temp sensor?? would not a simple 1n4148 also do the same thing?? dg9bfc sigi Am 18.11.2023 um 19:13 schrieb ajparent1/kb1gmx:

Allison, This is for two IRF510s in push pull. Each draws about 2A. Input is 4Ax 13.5v = 54watts. The 100v peak to peak is at the secondary of the PA transformer. The drain swing is about 35v peak to

Added is the bias circuit that I use and created by W1GHZ and N1JEZ for use with high power amps? using RF rated LDmos parts.? Its posted to show an example, not the only way. I could only post an

I got it, it is just a matter of adding another record edit form. I will get to it. - f

ps.: I want to make corrections in the saved file, because I cannot get involved in the process of automatic logging. -- Gyula HA3HZ

I correct the errors in the database, because the font size of the 7" screen is small. Therefore, when I want to correct it, I copy the sbitx.db file to a USB stick. Then I installed the DB Browser

Several things... One IRF510 spec is 100V breakdown.? More than that and poof. Also sustained current should be 4A or less (the 5.6A is for saturated switch mode). So the question is why it it 100V

Hello All, ? ? I hardly see any power out on transmit on SSB on any band. I can hear the relay click when I press the PTT button and speak into the mic and I see TX on the display but no forward

Joel, The all the IRF series exhibit this behavior. Just monitor the RF Output over 1 minute of key down. wrote: