Video looking at the RF power amplifier and the first couple of on-air contacts. To skip the first contact, go to 9:56. Thanks to Travis ZL2MLQ and Graeme ZL3OCT.
Hi Charlie . It's been a long while since I've commented and I am gonna comment more often . I really enjoy you content !!! Your solder work is so very nice ! Very logical layouts . Your work is beautiful art ! Thanks for sharing your process . Take care .
I must admit most of my builds are open air as I love to see all of the components and think about the role each one is playing. I then leave them on the shelf with an old tea towel as a cover. Each to their own I guess. I did make a nice nixie clock a few years back and that was mounted under glass for the same reason.
Hi Charlie, I discovered your channel at the start of this series and have been thoroughly enjoying it as well binge watching a lot of your previous videos to try and catch up. I really appreciate your construction technique and have tried it out with great success having just built a 100mw WSPR beacon to get started. Overall the experience has been very inspiring so thank you very much for all the effort you are putting into this! Cheers from Atlantic Canada, Rick VA1UAV
Thank you Rick. You are exactly why I am making the effort to put these up. As I've said many times, if I can do it (not perfect) then anyone can. Keep us posted on what you get up to. 73 Charlie ZL2CTM
@@CharlieMorrisZL2CTM I should mention for everyone's possible benefit that I found a drawing tool called DIY Layout Creator (freeware and easy to find) which is really helpful for laying out a circuit on veroboard especially with regard to where to cut the traces and then where the components go during assembly. I haven't heard you talk about it but then again I haven't managed to watch all the videos yet so please forgive me if this is old news :-)
Fantastic work again Charlie! I've really enjoyed following and building along with you in this series. I've tackled the mixers, crystal filters etc. but I've decided to make my central IF section two-way (rather than one way like yours) so I've built a Wes Hayward / Bob Kopski bidirectional termination insensitive amp. I'll need another for the other side of the mixer. I'd not tried one of these before: it was a bit fiddly to build (6 transistors) but seems to work very well. Anyway, thank you SO MUCH as always for your infectious enthusiasm. Keep on doing what you're doing! 73, Nick (M0NTV)
Congrats, it is quite an accomplishment to start off with nothing more than knowledge and components, put it all together, and actually reach out and talk to someone Km's away. I wonder if Travis watches your video's
I am planning to get me a 200 Mhz oscilloscope, then will test similar projects, such as the AD9951 DDS chip. Will use an Arduino and also the VFO, etc. Hopefully, the scope will do. Also, I got the Books Building a Transceiver by EI9GO and G4LFM and the Microcontroller Projects for Amateur Radio by W8TEE and AC8GY. My goal is to start from signal detection all the way to RF out, and hopefully build some kits. Nice job and thanks for sharing. 73.
It's around 5W. The power supply is an old laptop one rated for 24 VDC at 2A. If I de-rate that a bit then UI should have 40-odd W input power to play with. I'll keep experimenting with the IRF510 and see what I can do. I must admit that I find RF PAs a bit of a black art sometimes. Theory only goes so far.
You are actually driving a 61ohm load of the input to the IRF510, not a voltage hi impedance, so your driver needs to deliver voltage into this load. Your 2N2222 has an emitter resistor of 27R I think, so the stage gain is only 61/27. I know it is tempting to dampen the reactive input impedance of an IRF510 using 51R or so, but then your driver could have a bit more gain. A matching transformer 4:1 would give the 2N2222 a load of 240R and a gain of 240/27... I completely agree to using no emitter decoupling on the driver stages and use negative feedback to stabilise the stage gains. I am fiddling around my self with this, and have added serial R & C from collector to base to try to define the stages input impedances...not yet fully understood but I'm working on it!
I wish please make a website or blog and put all the contents like antenna calculation, circuit diagrams etc. Please also make a video how you measure TX power of output. 73🙂
Very nice. I am just about at the point where i need to start putting my rig together. I think i have all the parts ready finally. (Need to make the band pass filter still tho.)
Alsom sir. I am watching your videos with pleasure. My callsign TA9AAP. I hope to hear your voice with QRP when the hf propagation is peak on atmosphere. I guess this time will be in 2022 or 2023. Take Care and greetings from Turkey :) :) 73
BTW, the flange on the IRF-510 is hot electrically speaking. It's not an issue for the way you chassis your radios but shouldn't insulation be used between the flange and the heatsink?
Yes and no Rob. You may recall I have an old receiver chassis that I am keen to mount a transceiver into. It's either going to be this one or a rehash of an older one, which I'll talk about next.
Sounds good, I was wondering if it would maybe benefit from an AGC. There is quite a volume difference between some of the stations. I'm not sure how difficult it would be to incorporate into your current circuit. Or maybe try it on a future build.
Most certainly Brian. For this build I specifically did not pursue AGC in order to meet my idea of a simple rig. The rig I want to revisit next has AGC, which works very well.
Emphasizing the IRF510 as a voltage-controlled device (as opposed to a BJT) makes a lot of sense, and I've sometimes wondered why it's common to provide for 10s of mA of drive current when only a very-tiny amount of that current will make it past the gate of the MOSFET. Thus the 2N2219 or 2N3866 that are often used as a driver for MOSFET PAs seem like overkill, especially since a regular 2N3904 is rated at more than 100mA of collector current and capable of dissipating more that half a Watt of power. I'm sure I'm missing something vital, but it'll be interesting to see what you come up with using a voltage-centric design. 73, Todd K7TFC
Great point - something I've been working on while trying to make a mosfet gate driver for a class E amplifier. I think why 2n2291 is preferred over 2n3904: storage time. 2n2291 switches from on to off in 10 ns, 2n3904 takes 200ns.200ns is too slow for HF. So you'd have to add speed up capacitor and Baker clamp to 2n3904 while 2n2291 "just works."
Great video, as always. One little observation though. Shouldn't the attenuator be placed between the mixer and the filter? There is little sense to place it after the filter, before the PA. The PA will see 50 Ohm in the bandpass in any case, but the filter will reflect the unwanted signals back to the mixer outside of the passband.
Out of habit Alex. More often than not for the smaller rigs I have more room at the input to the driver to add attenuation. I must admit I see it most at the input to RF amps.
[18:41] another little observation - IRF510 actually doesn't have high input impedance on HF. Its impedance is mostly Ciss which is ~180 pF for Vds = 13.8 V. The total input impedance would be 51 || [ 1/(2*pi*F*Ciss) ]. High Ciss is one of the reasons why it's difficult to make a wideband PA with IRF510's (it's difficult to match in the wide frequency range) and why RD15 / RD16 with lower Ciss work much better.
Wow! Charlie sounding great and doing a good job. I think your right in working on the driver for the IRF510 a little more simplified if possible. but it looks like you have a very nice reference radio there with plenty of room for experimenting with each component of the radio. you left plenty of room to test modules side by side. I have seen an AB amplifier with 2n3904 and 2n3906 in push-pull, maybe would that give you enough drive for the IRF510? I don't know just thinking out loud with things I have seen in the past. I know you were trying to keep it common components. Speaking of common components, It is my feeling that the SI5351 is today's VFO of choice. it is not exotic, it's easy to get much easier than a large variable capacitor. I think the old parts that started radio are getting to be exotic so it's time to move on. or we will be spending lots of time building our own variable caps with big square plates of metal like they did in the 20's. lol Have a great weekend Charlie!
Thanks Kurt, much appreciated. The Si5351 board (the ones I use) cost $3 so you really can't go wrong. A lot less frustrating than trying to source and build a stable analog VFO. The software also gives you so much flexibility to tweak freqs. Again, it works for me.
@@CharlieMorrisZL2CTM You are definitely on the right track by using that from my point of view there is no other logical convenient way in today's times.
@@canaldopicco I think I remember the PN junction type I'll have to look at it more again. we can get anything here in the USA however the price is the problem. if you buy a nice variable capacitor it about $20 or a cheap plastic version $4 or we get a Nano, SI5351 and display for $10 or less. so it's just really looking like the future is digital. it really doesn't matter now but a number of years ago the SI5351 was not around. at least we have that now. A lot of people like to make their own VFO and keep it to the old style.
Hi Charlie, great videos! I was wondering if you know a good source to get the toroids you used in this project, locally in NZ. Cheers from a fellow Kiwi!
