48 - RF Driver & Pre-Driver Amps

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Nick M0NTV builds and tests an RF Driver and Pre-Driver Amplifiers as part of the transmit chain of his current homebrew project: a 15m & 10m SSB transceiver.
Downloadable Resources
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SCHEMATICS
RF Driver
drive.google.com/file/d/1-aWl...
RF Pre-Driver
drive.google.com/file/d/1pd-e...
26.6 MHz Notch Filter
drive.google.com/file/d/15vu5...
30 MHz Low Pass Filter
drive.google.com/file/d/1XLp1...
LTSPICE SIMULATIONS
RF Driver
drive.google.com/file/d/1_Kt4...
RF Pre-Driver
drive.google.com/file/d/1P8IX...
26.6 MHz Notch Filter
drive.google.com/file/d/10gBY...
30 MHz Low Pass Filter
drive.google.com/file/d/1K5Y7...
Makis SV1AFN website: www.sv1afn.com/en/products/-8...
Building A Transceiver (Eamon Skelton & Elaine Richards):
amzn.eu/d/dKmcMYl
Thanks very much for watching.
73,
Nick
M0NTV

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Опубликовано:

30 янв 2024

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Комментарии : 45

@BalticLab 2 месяца назад

3:35 All of it! 🙂

@acestudioscouk-Ace-G0ACE 5 месяцев назад

Thanks for making another great video Nick! It certainly helps me on my learning curve. I had never really thought about the chain of amplification required to feed the driver and this video explains it well. I'm really looking forward to learning how impedance matching through these stages works and the improvement it makes. Best 73, Ace G0ACE

@M0NTVHomebrewing 5 месяцев назад

Thanks very much Ace! 73, Nick

@alanmacdonald65 5 месяцев назад

Great video Nick, as always. I love the inquisitive streak that drives you to take published designs and think "can I make this better"? The answer seems always to be YES!!!

@M0NTVHomebrewing 5 месяцев назад

Cheers Mate! It doesn't always work out quite as well. The Pre-Driver I designed and built myself initially worked really well until the transistor failed and went short circuit. The current limiting resistor made a valiant attempt before bursting into flames! The magic smoke was released and it was back to the drawing board. It's all part of the fun though. I did actually manage to get to the Club last Wednesday and it was good to see some familiar faces - and some new ones too. Thanks again. See you soon. 73, Nick

@christianblack2916 5 месяцев назад

appreciated. I did get the book and am dipping in

@M0NTVHomebrewing 5 месяцев назад

Thanks Christian. Yes, it is a very useful book. 73, Nick

@Dazzwidd 5 месяцев назад

I bought it just for a read, good book 1👍

@johnwest7993 5 месяцев назад

Thank you Nick. You and Charlie Morris have my favorite ham channels, but neither of you post enough videos to make me happy. But I've just ordered the book you recommended and that will give me something to help keep me busy between your videos. :) BTW, when I build anything, my goal is to completely over-engineer it. Because I am doing it as a hobby project, and saving the cost of a commercial product I can take my time, use more and better parts and circuits, tune for absolute optimums, and actually build something better and more rugged than a commercial product, one that I can be very pleased with.

@M0NTVHomebrewing 5 месяцев назад

Thanks very much John. Yes, you are right about building your own stuff - you can make it exactly as you wish. Enjoy the book when it arrives. 73, Nick

@Dazzwidd 5 месяцев назад

Have you seen mikrowave1?

@ornithopterindia 5 месяцев назад

👍Thank you sir.

@M0NTVHomebrewing 5 месяцев назад

You are very welcome. 73, Nick

@khimbittle7705 5 месяцев назад

Enjoy your videos

@M0NTVHomebrewing 5 месяцев назад

Thanks very much. 73, Nick

@andyhunter5191 5 месяцев назад

Hi Nick, great video and thanks for sharing the LTSpice files. Please can you provide a link to the spice models for the 2N3866 and RD06 devices.

@M0NTVHomebrewing 5 месяцев назад

Hi Andy, I'm sorry but I'm afraid I can't give you a link. I suggest doing what I did and just Google "2N3866 Spice Model" etc. The RD06HHF1 is more tricky but it IS out there ... somewhere. Seek and you will find! Happy hunting. 73, Nick

@edgeeffect 5 месяцев назад

I love how tidy your Manhattan and "Gougey-Scrapy" PCB's are. These techniques can both lead to quite a unruly mess of a layout, but yours are works of art! "Gougy Scrapy"... Is there a popper name for the technique where you scrape away the copper to make little lands on the PCB? Those remind me a bit of the Dremeled boards that "diodegonewild" makes but with a big ground plane.

@M0NTVHomebrewing 5 месяцев назад

Thanks very much. I've always referred to it as the 'Dremel Method' or 'Engraving Method' but I like your 'Gougy Scrapy' much more! Thanks again for watching and commenting. 73, Nick

@mfwwhelan7561 5 месяцев назад

Hi Nick. Very helpful video. Can you tell me where you sourced the RD06HHF1 devices? Thanks, Mike, EI6AU

@M0NTVHomebrewing 5 месяцев назад

Thanks Mike. I think it came from here: www.sdr-kits.net/RD06HHF1 You can get them much cheaper from China but I wanted to be more confident I was getting the original device and not a cheap clone. Hope this helps. 73, Nick

@mfwwhelan7561 5 месяцев назад

Thanks Nick. I recently bought several fakes from China.@@M0NTVHomebrewing

@tdumnxy 5 месяцев назад

Great stuff, as per your usual high standards. Do you have any thoughts, are there any downsides to "overshooting" required output voltages and then having to attenuate? I second your recommendation of LTspice. I had a play a few months back and I think it can also serve to satisfy the urge to do some experimentation when getting out the soldering iron is not possible.

@M0NTVHomebrewing 5 месяцев назад

Thanks Stephen. That's a good question. I imagine every resistor in the current path will have some effect on the overall noise figure. However, I've found attenuation to be one of the most useful tools in the homebrewing toolbox. A pi attenuator can also help to establish a better 50Ω impedance on a port. I agree about LTSpice - it's a great way to play with ideas. 73, Nick

@Dazzwidd 5 месяцев назад

That's pretty meaty for 1W output. It looks more like 4W

@M0NTVHomebrewing 5 месяцев назад

The Mitsubishi MOSFET will do more but Eamon Skelton's design limits it to 1W. Better to build in some headroom and keep it cooler! 73, Nick

@Dazzwidd 4 месяца назад

@@M0NTVHomebrewing well actually that amount of headroom would enable you to get a very linear performance by running the bias current up a touch. if you are planning on amplifying AM or SSB signals, it is highly desirable to have the best linearity you can

@M0NTVHomebrewing 4 месяца назад

This would mean redesigning the bias network. Skelton's design intentionally has an active bias to guard against thermal runaway (his first design used a BJT). The design with the RD06HHF1 already has a pretty high standing current of about 230mA. You're right about trying to get the best linearity possible. Skelton estimates the Third Order Intercept Point of +45-50dBm so I think linearity will not be an issue with this amplifier. Thanks very much for watching and commenting. All the best in your own building. 73, Nick

@Dazzwidd 4 месяца назад

@@M0NTVHomebrewing yeah, that's not bad. I'm mucking around with different circuits at the moment to this, and as always I am starting from scratch, doing it from my head with experimental tinkering. It's FM microphones at around 100mhz presently which run on single 18650 li-ion batteries. I'm getting ridiculously high audio sensitivities and fidelity, and I can plug the RX into my phone and use the voice recorder to record it via another device I made. Playing with ideas is always good fun when they work well 😁

@mladencukon9a3xz79 Месяц назад

great....Nick, can i try with 2n5109 ?

@M0NTVHomebrewing Месяц назад

Hi there! Yes, Makis' original design uses a 2N5109. I haven't used one myself but I think it is pretty similar and if anything might be rated for a bit more power. You should be fine! Thanks very much. 73, Nick

@mladencukon9a3xz79 Месяц назад

@@M0NTVHomebrewing thanks, i try with 2n5109 but Ei9GQ driver from the book is also flat gain and very good...

@DAVIDGREGORYKERR 6 дней назад

What about using to 2x 75R to 300R BALUNs for the RF Power stage where you have a BALUN for the Base Drive and the output BALUN to get the SWR down to a suitable level.

@M0NTVHomebrewing 4 дня назад

I've actually been experimenting with some transmission line transformers since my mini-series in impedance matching. My next PA will definitely have better transformer-based input and output networks! You live and learn. Thanks. 73, Nick

@DAVIDGREGORYKERR 6 дней назад

What about the RSGB VHF/UHF Handbook 4 edition shows you how to build a synthesized 144Mhz Transceiver.

@M0NTVHomebrewing 4 дня назад

I'm sure that is great if you are building a transceiver for 2m. I was only shooting for 21 - 30 MHz here.

@donepearce 5 месяцев назад

1080p but your camera footage is really fuzzy. Are you recording at much lower quality then upsampling for the final mix? Great content, though.

@M0NTVHomebrewing 5 месяцев назад

Sorry. I know the camera action can be less than perfect. It is all supposed to be 1080p but I suspect some of the handheld footage may be 720p. I really need to invest in some better equipment now I think! Thanks for watching anyway. 73, Nick

@donepearce 5 месяцев назад

@@M0NTVHomebrewing Not a problem - I know the feeling. But it wasn't the handheld stuff that was fuzzy - it was your talking head bits with the fixed camera.

@M0NTVHomebrewing 5 месяцев назад

@@donepearce Thanks for letting me know. That'll be the camera in my Mac. I'll investigate! 73, Nick

@DAVIDGREGORYKERR 6 дней назад

Have you ever tried using 74HC4053 chips in a DBM mixer with transformers on both sides.

@M0NTVHomebrewing 4 дня назад

No I haven't tried that David. I tend to stick with passive diode ring mixers. 73, Nick

@DAVIDGREGORYKERR 6 дней назад

VN66AF VMOS FETS might be better up to 60W of RF.

@M0NTVHomebrewing 4 дня назад

I haven't looked at those David but in reality I only wanted 10W from the final power amplifier so using a device that can produce up to 60W of RF in the driver seems something of an overkill in my instance. I only needed my driver to give me 1W max. I'm mostly a QRP chap these days. 73, Nick