F-5 Transistor Kit
Included in this kit are the semiconductors needed to complete an F-5 amplifier, with the exception of the input JFETs, which can be sourced separately through the store. MOSFETs were matched in accordance with standard operating conditions. This is enough MOSFETs for 2 channels (one stereo amplifier).
- 2 x IRFP240
- 2 x IRFP9141 (replacing IRFP9240)
- 2 x ZTX450
- 2 x ZTX550
- 2022-04-20 - At Nelson's suggestion, this kit contains Harris P channel MOSFETs instead of International Rectifier MOSFETs. These are considered better parts, with less distortion, and match nicely (.1V Vgs at 0.1A). They have a lower maximum voltage at 100V however 100V is suitable for this application.
I live in the UK, the transistors and boards arrived within two weeks. The build was straight forward and housed in a 4U Galaxy case. The two 500 VA transformers are bolted the the front panel. It’s not pretty but it’s functional. Unfortunately the build guide called for the bias and offset pots to be rotated fully anti clockwise before power on. At power on the two boards fried themselves with added dramatic smoke. The penny dropped, maybe next time I’ll ensure the pots are fully clockwise before turn on. I replaced two blackened resistors on each board and ordered a new set of transistors, just to be on the safe side although the previous traumatised ones tested OK. Second power on no smoke or blackening slowly increased the pots counter clockwise following the build guide to 0.59 volts. Heatsinks about 50 degrees C when stable. It sounds fantastic. I was so impressed I have since ordered the boards and transistor kit and built an F5 Turbo in a 5U Galaxy case. which sounds about the same but slightly more dynamic. The bias issue was not a problem with the Turbo as you set the bias pots to full resistance via test points. Prior to switch on. Two superb products that sound amazing. I’m presently building a Pearl 2 Phono stage from Pass DIY. Thank you Nelson, Wayne and all the team at DIY Audio.
Fast service. The match was excellent. I used the Mosfets in my M2X and set the offset pot to center the bias resistance between the P and N sides. . Upon power-up I only needed to touch up the offset.
Yes, then F-5 transistors have been received and PCB came a little earlier, so now is the time to collect the rest of the necessary components. But the summertime that comes now makes the Diy activity go down a bit.
Perfect qualityband fast delivery thanks. Greatings from Switzerland
Peace of mind by buying from diyAudioStore. Save me money since I don't have to buy a bunch of those mosfets and matching them myself (no hassle).
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