HFU HF Underground
Technical Topics => The RF Workbench => Topic started by: CharlieFoxtrot on April 26, 2018, 2007 UTC
-
Hello everyone! CF here! As the title says, iīm new on circuit building, but trying to do someting. Iīve been thinking about building the Grenade, to start a PRadio now that iīm living in the countryside, but havenīt seen enough examples to know if the schematics i found online (see below) are working or not. There are at least 3 or 4 different variations, but no examples. So, is it something you can recommend to start? Could i have a happy ending trying to build it? Is there any other transmitter you could give me advice with about 10w?
Thanks in advance.
CF
http://worldwidedirt.tripod.com/gproject.html vs http://am-transmitter.blogspot.cl/2014/07/grenade-transmitter.html
-
Stick withe the LuLu design, I can send you a PCB if you want?
Str.
-
I agree. As a beginner, its a lot easier to start with something that works, learn how it works, then build your own. Thats what I did many moons ago.
+-RH
-
Stick withe the LuLu design, I can send you a PCB if you want?
Str.
PMd
-
Itīs impossible not to think about the LULU. It sure itīs a great TX. Believe me, itīs been in my sight for a long time already. Thnk you both.
CF
-
Single ended class E is as simple (and efficient) as it gets.
I've heard folk say it was complex when it's actually simpler than most other modes of RF generation as it doesn't need bias for a start.
Using the 74HC240 and an IRL510 (IRF510 wont work BTW despite lots of designs say it does, IT DOESN'T!) your're good to 8MHz or so.
Ive seen the cap across the FET specified as 68p which must have been a typo as 680 is nearer the mark, I use 470p as you can use them for all the O/P caps (1n5 = 3x470)
COG/NPO caps are essential, you can however get away with X7R for the coupling cap, HV COG's at this value are VERY expensive!
Also using T50-2 toroids is stoopid as they're way too small and get roasting hot, T80-2 abs min, T94-2 perfect and T106's for the 40W GaN version.
So this is the ONLY design to use (it's not mine BTW!), every other is pants, overly complex, doesn't work, uses way too many unobtainable components etc etc.
Also having a broadband driver makes it work on any freq, just change the 7 components to RHS of FET.
Str.
-
I've got an original Greande and know the maker well. Other than few standard parts and using the same basic circuit, they're all different due to the fact he utilized scrounged parts and what he had around the place to put different runs together. Then he'd scratch the parts numbers off so they couldn't be traced back to him. (Enforcement was much tighter then). That's why it took about 13-14 years for the thing to be repeatably back engineered.
He designed and built the first one in I think 1992? While they're great little transmitters, the parts, especially the style of transformers he rewound for the mod trannies, are getting as hard to find as hen's teeth. As much as I'm a Grenade man and think the world of it's inventor, stick with something you can easily get parts for and build.
-
If you squeeze a few more watts out of a Grenade, they drive a pair of 813's with ease ;)
-
"While they're great little transmitters, the parts, especially the style of transformers he rewound for the mod trannies, are getting as hard to find as hen's teeth. As much as I'm a Grenade man and think the world of it's inventor, stick with something you can easily get parts for and build."
Can you point me to the rewind instructions for what I'm guessing it's the old radio shack transformer? I have one of those and while I'm away from the shack if really like to know how to rewind it.
Having said that Stretchy s toroidal design early makes nice audio too
-
Just wind it 2:1 ratio.
Parts aren't rare, just hard to find.
You can buy formers and iron laminations from any transformer manufacturer.
Use the '160' size as is very common.
Str.
-
I wish I could Syfr, but it was part of a Yahoo group on homebrewing sw pirate transmitters. When my Yahoo addy's disappeared in the Great Yahoo Hacks of 2015/16 I lost access to the info.
I still have a few of the xformers around. They were Rat Shack automotive hash filters, but I can't recall the mod details. The one problem with them is the bottom end drops to nothing at about 80 hz. If you want fat bass you're not going to get it unless you know how tweak the audio to compensate for it.
Brian, all the Grenades built by the Animal did about 14 watts out, despite the 10 watt claim. I've known a couple of guys that drove tube amps made for ham use with them.
-
Dunno if rat shack still carries these, but I've one of their nib 20a auto noise suppressor dealy sitting here. A toroid would surely be easier to deal with in both acquisition and construction.
-
Yup, you had to open it and wind another 20 turns of I think 22 gauge enamel wire around it, then get it back together. Everyone was so happy we'd finally cracked the mystery of the Grenade, we were just glad to have a way to modulate the thing.
The modified "Lulu design" came out of that group, too, as did the Corsair. The "Lulu" actually came from a schematic a South American guy had posted on the internet. Man, there were a ton of people contributing to that group!
When my Yahoo account went "boom!" in the Great Yaoo Hack of 2015, I lost my access. I don't know if the group is still active or not?