Microstrip RD06HVF1 amp

[OgreVorbis]

I am looking for a fully microstrip no-tune amp with RD06HVF1. I want to integrate this design into a transmitter board I'm building. Anyone know where I can find this? If someone wants to design one for me, I'd also be willing to pay. So far I have the exciter board designed in sprint layout, but I want to add an amp and the problem is I don't know how to calculate the matching for the amp. The output of the board is currently aprox 125-150mW. That should be enough to drive the amp, right?

[Analyser]

Designing a microstrip circuit is not trivial and if you pay someone to do it professionally the cost would probably be prohibitive for your project.
If you have accurate impedance data for the RD06 then there are some free software applications which can do this (MIMP, RFsim99) but just beware that even once you've designed a circuit you'll probably need to do several board designs to get it working well. One of the reasons for ths is the variation in dielectric constant from different manufacturers of PCB material. A common PCB laminate is called FR4 but all FR4 does not behave the same at 100MHz! Other effects like parasitics, coupling of adjacent lines and physical component layout have an effect as well.

My advice would be to have a look at someone else's design, make a similar layout and modify to suit your needs. Enigma do a nice-looking microstrip RD15 amp and from experience the RD06 and RD15 are quite similar so that would be a good starting point.
I think the Dutch have also done one (RDVV?) but I can't remember if it was just the LPF or the input and output matches that were microstrip.
Google is your friend!

When you decide which way to go, please post your results here, I'm sure everyone can learn from your experience.

[shorty]

There's a RD15 strip line design posted on this German site, i don't read German so no idea what it says, the pcb layout is at the bottom of the page in the link, i've tried to post the images here but for some reason it will not let me add files.

https://www.mysnip.de/forum-archiv/them ... ayout.html

[Analyser]

There's a RD15 strip line design posted on this German site, i don't read German so no idea what it says, the pcb layout is at the bottom of the page in the link, i've tried to post the images here but for some reason it will not let me add files.

https://www.mysnip.de/forum-archiv/them ... ayout.html

That's an old 2SC1971 design done by the guy from Aspisys in Greece, years ago. I'm quite surprised it works seeing as one device is bipolar and the other a FET, but if it works then you can't argue really!

[MiXiN]

Designing a microstrip circuit is not trivial and if you pay someone to do it professionally the cost would probably be prohibitive for your project.
If you have accurate impedance data for the RD06 then there are some free software applications which can do this (MIMP, RFsim99) but just beware that even once you've designed a circuit you'll probably need to do several board designs to get it working well. One of the reasons for ths is the variation in dielectric constant from different manufacturers of PCB material. A common PCB laminate is called FR4 but all FR4 does not behave the same at 100MHz! Other effects like parasitics, coupling of adjacent lines and physical component layout have an effect as well.

My advice would be to have a look at someone else's design, make a similar layout and modify to suit your needs. Enigma do a nice-looking microstrip RD15 amp and from experience the RD06 and RD15 are quite similar so that would be a good starting point.
I think the Dutch have also done one (RDVV?) but I can't remember if it was just the LPF or the input and output matches that were microstrip.
Google is your friend!

When you decide which way to go, please post your results here, I'm sure everyone can learn from your experience.

Those RD15HVF1 Amps and his newer 60W Amp seems to have disappeared off the Enigma site.

Was interested in buying one of the 60w ones as well, but hey ho.

[yellowbeard]

Does it have to be stripline? The FRB design is simple enough and no-tune, I've had over 8 watts out of it. The FET WAS sweating like a paedophile in a barney suit though...

Code: Select all

https://www.scribd.com/doc/8310351/FRB-6-Watt-Instruction-Packet

[Albert H]

Dunifer's power amp designs are pretty foolproof - they're designed for people with little or no experience of RF construction to be able to build. Many years ago, I debugged his older PLL exciter (there were some strange synthesiser artefacts sneaking out), and he gave me a couple of his 40 Watt bipolar transistor PAs in return. They were put to good use in Los Angeles for several years.

It might have been the world's first entirely solar-powered radio station - "40 Watts out of nowhere". The rig in the hills was powered by a couple of big RV batteries, and these were charged by a big solar array (a donation from a friend who works at a company that makes them). There was a battery condition monitoring circuit, and a telemetry signal was included in the main carrier, which drove a battery indicator back in the studio! The link was UHF, using ordinary TV Yagis at both ends, and the transmit aerial was (eventually) eight co-phased three-element Yagis, pointing in the way we wanted to go - towards the centre of population. We had a consistent stereo signal over a large part of the suburban area of LA, and we had sufficient interested and able people to provide night time programmes 7 days a week.

We only ever missed two evening broadcasts - when we were taken off the air by a lightning strike! I replaced the PA with the second one, identified and replaced the fried coax, mended the link receiver, and we were back on again!

Despite the low power (particularly compared to the ½MW flamethrowers either side of us, we got a huge following. We were lucky enough to find a gap in the band that had 300kHz either side of us, and mod levels were strictly enforced by the FCC, so that the neighbours didn't splatter us. Our little signal - whilst weaker than its neighbours - was of consistently high quality and carried varied and interesting programming. We had a bigger audience than the big "legitimate" stations in many instances, and we scared the hell out of the big boys! That was fun radio!

[Analyser]

Does it have to be stripline? The FRB design is simple enough and no-tune, I've had over 8 watts out of it. The FET WAS sweating like a paedophile in a barney suit though...

Code: Select all

https://www.scribd.com/doc/8310351/FRB-6-Watt-Instruction-Packet

Some of those FRB designs look a bit dodgy. Was it not Ogrevorbis (the OP) himself who built the 70W FRB amplifier and could not get it working, for love-nor-money?
It might be a fake FET or whatever, but I'm still not convinced.

[Albert H]

I've seen Dunifer running one of his "Radio Bootcamps", where he teaches beginners how to assemble transmitters. All the published designs work - indeed, they work well - and they're designed to be easy to build, be entirely reproducible and not too critical. All his circuits are now broadband, so that no actual tweaking is required - it's set the PLL where you want it, and away it goes.

[OgreVorbis]

Some of those FRB designs look a bit dodgy. Was it not Ogrevorbis (the OP) himself who built the 70W FRB amplifier and could not get it working, for love-nor-money?
It might be a fake FET or whatever, but I'm still not convinced.

Yes, it was me. It may have worked if I had used the original broadband design, but I decided against it after hearing about the efficiency and low output power. I tried a narrowband design and failed.

Does it have to be stripline? The FRB design is simple enough and no-tune, I've had over 8 watts out of it. The FET WAS sweating like a paedophile in a barney suit though...

Code: Select all

https://www.scribd.com/doc/8310351/FRB-6-Watt-Instruction-Packet

The reason for the stripline is that I want it to be easy to build and professional looking. I think I may also end up selling this on ebay. Coilcraft might be an option though.

Something like this looks good. I may try to duplicate it. The 1W in makes me think those resistors are an attenuator on the input. 1W in with only 5W out from the RD06HVF1 seems wrong if it's not.
http://www.ebay.com/itm/87-5-108MHz-FM- ... SwzrxUsUa7

[Analyser]

The 1W in makes me think those resistors are an attenuator on the input. 1W in with only 5W out from the RD06HVF1 seems wrong if it's not.

That's correct, 1W would be too much input for that device unless it's attenuated.

[Albert H]

http://www.ebay.com/itm/87-5-108MHz-FM- ... SwzrxUsUa7

....looks very like a smaller version of the module amplifier case I use for 200MHz amplification. The machined aluminium block (from China, of course) has heatsink fins on one of the big faces (which the FETs screw down to, and they've even machines tapped (M3) holes to screw a 120mm fan to the heatsink side.

My linear DAB PA (with lots of negative feedback to broaden and equalise its response throughout Band III) gets 75Watts out of a pair of 80 Watt Philips FETs (very under-run) and the response is entirely flat from 160MHz to 250MHz. It's probably the trickiest RF design I've ever done!

Those aluminium module cases are brilliant. One of the German guys that I know (in Berlin) is building his Band II PAs in that kind of box. His rigs look quite weird inside, because there's just a SMPSU, then some modular aluminium boxes with the various sections inside them. They're coupled together with short coax leads with SMA connectors.

[radium98]

http://radioinitiation.chez-alice.fr/en ... pli5w.html
this a good site and author is french he sold this amp and other important stuff if u bought it please post the layout here thanks.