Technical Topics > The RF Workbench

New here and already with doubts (tx)

<< < (2/4) > >>

Charlie Foxtrot Mike:
Well, had the list almost ready and then found a store here(1500km away, but same country) where good electronic stuff can be found. Searching their catalog I realized there's no IRF510 available, but irf840 and the IRFZ44N. Could I use any of those without having to modify something else? Reading the comments of the site, they say the IRFZ44N works the same. If so, I could buy everything here and not in China. Thanks.
CFM.

Here's the data sheet.

ff:

--- Quote from: Charlie Foxtrot Mike on June 09, 2015, 1436 UTC ---Searching their catalog I realized there's no IRF510 available, but irf840 and the IRFZ44N. Could I use any of those without having to modify something else? Reading the comments of the site, they say the IRFZ44N works the same. If so, I could buy everything here and not in China.

--- End quote ---

Can't say for sure.  The thing is, these garden variety MOSFETs are designed for passing DC current - or - low frequency AC.  The 510s and their ilk were designed back in the 70s for automotive service.  They were used for such "AC" applications as flashing turn signals and the like.  We are taking what is basically a low frequency device and using it far outside its design parameters.  That's why I can't tell you for sure if one will work and another one won't.  I know from experience that 510s, 511s, 520s, and 530s will usually work in these designs.  But even 510s will vary in performance in these circuits due to manufacturing irregularities and HF performance is not a concern with the quality control people.

Looking at the IRFZ44 sheet I immediately see that the Miller charge is MUCH higher, which will hamper its RF performance because they require more drive at RF.  You really should try to get a few 510s (or 511s) if you plan to play with these circuits.  You'll have enough debugging to do without making yourself yet more work by using a compromised device.  If you have a Paypal account you can usually find what you need on EBAY and Paypal automatically does the currency conversion.  Good hunting!

Pigmeat:
Fred, would it be possible for him to salvage a mod tranny from one of those old CB's and use it in the Guerrilla?

ff:

--- Quote from: Pigmeat on June 09, 2015, 2311 UTC ---Fred, would it be possible for him to salvage a mod tranny from one of those old CB's and use it in the Guerrilla?

--- End quote ---
Absolutely, Pigmeat!  The impedance match would be close enough for the 5-10 watt range.  If built flawlessly, his Guerilla will probably put out about 5 watts of carrier, or maybe 6.

Charlie Foxtrot Mike:
Great to know! The irf510 that I need, must be the IR original? Cuz the Vishay are available almost everywhere. In fact, the whole list in Aliexpress costs about 30 usd , but then I'll have lots of each component... What's not bad (as long they aren't too bad quality). I'm so motivated that I already started learning basic electronics :).  I'll keep you informed guys. Thanks and salud!
CFM

Navigation

[0] Message Index

[#] Next page

[*] Previous page