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 Hi all - I decided to add some big-boy shoes to my homebrew QRP rig.? I decided to build the 16 watt power amplifier designed by EI9GQ, Eamon Skelton in his book "Building a Transceiver".? The amp used two Mitsubishi RD16HFF1 transistors in a push pull configuration.? On the bench I measured about 13.25 dB gain across the HF bands.? I can't wait to test it in my rig.? This was a fun build an not nearly as difficult as I had imagined,. Details on the build are on my blog - check it out and follow or like it if you choose. 73, Dean KK4DAS
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You might want to consider putting band pass/low pass filter?on the output - push-pulls are known for being "dirty" with third order harmonics. At 16 watts, I doubt you would get in too much trouble, but if you're transmitting happily on 40 and are heard on a segment of 15 where you should not be, even at a half watt or so, it might get you a letter in the mail.
On Tue, Oct 5, 2021 at 2:16 PM Dean Souleles < dsouleles@...> wrote:
Hi all - I decided to add some big-boy shoes to my homebrew QRP rig.? I decided to build the 16 watt power amplifier designed by EI9GQ, Eamon Skelton in his book "Building a Transceiver".? The amp used two Mitsubishi RD16HFF1 transistors in a push pull configuration.? On the bench I measured about 13.25 dB gain across the HF bands.? I can't wait to test it in my rig.? This was a fun build an not nearly as difficult as I had imagined,.
Details on the build are on my blog - check it out and follow or like it if you choose.
73,
Dean
KK4DAS
--
Alex Netherton, W5ALX
Buncombe County NC, EM85ro
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Alex,
Always best practice to have a low pass filter after the amplifier.? In my rig, the PA comes just before the LPF. It is already built.
Dean
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I kind of figured as much... most of us know that, just wanting to help in case of a newbie! 73!
On Tue, Oct 5, 2021 at 4:56 PM Dean Souleles < dsouleles@...> wrote: Alex,
Always best practice to have a low pass filter after the amplifier.? In my rig, the PA comes just before the LPF. It is already built.
Dean
--
Alex Netherton, W5ALX
Buncombe County NC, EM85ro
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?Dean - Does it work at all on 50MHz?
James Duffey KK6MC
Cedar Crest NM
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Hi James -?
The RD16HHF1 is spec'd for 30MHz.? I have never tried it on 50 nor do I have any equipment to test it with.
73,
Dean
KK4DAS
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On Tue, Oct 5, 2021 at 11:16 AM, Dean Souleles wrote:
Details on the build are on my blog - check it out and follow or like it if you choose.
I like the information on how you created the engraving files.? I've been looking to take my little CNC engraver out of retirement. This type of low density construction that is often done with cutout squares of PCB glued to a main PCB, Manhattan style, seems a perfect match for these cheap CNC routers to cut the isolated pads into the PCB board. And maybe some of the connection traces, as well.? Tom, wb6b
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The RD16HHF-1 works fine on 6m it will also work higher , I have used them all the way to 222. Both the VHF and the HF transistor are essential the same transistor only sorted for a certain gain at the upper frequency limit. Those that don't make the gain are branded for HF, Those that make the gain are branded for VHF/UHF. I have used RD16HHF-1 on 6m and 2m but they fall off above that, some do 220 within specs some not, none does 432 within specs.My 6m ,2m, and 222 transverters? all use the HF branded transistor without a problem, although I had to try several of them on 222 before I found one that worked at full gain.
John
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Better try RD16HVF1 pair instead.?
Sarma
Vu3zmv
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I have had considerable success with IRFZ24N. This was discovered by W6JL for his ARRL Homebrew contest winning entry. The IRF510s, idled back to provide 2 watts of drive can easily push a pair of IRFZ24Ns for clean 50 watts power with 13.8v power supply. - f
On Thu, Oct 7, 2021 at 11:44 AM MVS Sarma < mvssarma@...> wrote: Better try RD16HVF1 pair instead.?
Sarma
Vu3zmv
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Thanks for including the write up from W6JL.? very interesting and informative.
Alex wd2t
On Thu, Oct 7, 2021 at 6:04 AM Ashhar Farhan < farhanbox@...> wrote: I have had considerable success with IRFZ24N. This was discovered by W6JL for his ARRL Homebrew contest winning entry. The IRF510s, idled back to provide 2 watts of drive can easily push a pair of IRFZ24Ns for clean 50 watts power with 13.8v power supply. - f
On Thu, Oct 7, 2021 at 11:44 AM MVS Sarma < mvssarma@...> wrote: Better try RD16HVF1 pair instead.?
Sarma
Vu3zmv
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I have also had good success with the W6JL amp and both FET's he used..? I had PCB's made for it (less the relay switching) and my build can be seen here if interested.
Glenn
vk3pe
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On Thu, Oct 7, 2021 at 09:04 PM, Ashhar Farhan wrote:
I have had considerable success with IRFZ24N. This was discovered by W6JL for his ARRL Homebrew contest winning entry. The IRF510s, idled back to provide 2 watts of drive can easily push a pair of IRFZ24Ns for clean 50 watts power with 13.8v power supply.
- f
On Thu, Oct 7, 2021 at 11:44 AM MVS Sarma < mvssarma@...> wrote: Better try RD16HVF1 pair instead.?
Sarma
Vu3zmv
?
?
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Glen, the amp block is now a part of the sbitx radio. - f
On Fri, Oct 8, 2021, 6:58 AM Glenn < glennp@...> wrote: I have also had good success with the W6JL amp and both FET's he used..? I had PCB's made for it (less the relay switching) and my build can be seen here if interested.
Glenn
vk3pe
On Thu, Oct 7, 2021 at 09:04 PM, Ashhar Farhan wrote:
I have had considerable success with IRFZ24N. This was discovered by W6JL for his ARRL Homebrew contest winning entry. The IRF510s, idled back to provide 2 watts of drive can easily push a pair of IRFZ24Ns for clean 50 watts power with 13.8v power supply.
- f
On Thu, Oct 7, 2021 at 11:44 AM MVS Sarma < mvssarma@...> wrote: Better try RD16HVF1 pair instead.?
Sarma
Vu3zmv
?
?
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I built an amp almost identical to this one. I used the RD16HFF1 mosfets. It gave between 16 and 20W output from 80m to 10m, and 6W output on 6m. During sporadic E I worked several thousand km on SSB with the 6 watts, and it should be sufficient for a larger amplifier.? Here in the UK was also have &0 MHz (4 metres) but I didn't try these mosfets on that band.
Tony, G4CIZ
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On Wed, Oct 6, 2021 at 08:31 PM, Tom, wb6b wrote:
Manhattan style, seems a perfect match for these cheap CNC routers
Yes, indeed.? Here are a few more boards I cut on the CNC.? And once the design is done it's a snap to knock out another one. Dean  
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On Thu, Oct 7, 2021 at 06:04 AM, Ashhar Farhan wrote:
I have had considerable success with IRFZ24N. This was discovered by W6JL for his ARRL Homebrew contest winning entry. The IRF510s, idled back to provide 2 watts of drive can easily push a pair of IRFZ24Ns for clean 50 watts power with 13.8v power supply.
Thanks Farhan. Now that I have built one amp I'm losing my fear of building another :).? A little bit of experience and great Elmer's like you, Pete and Bill goes a long way! 73, Dean
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Hi,
Thanks forpointing out the IRFZ24N. I hunted it down and started looking at specs. I will probably get a few in here and give them a try. I haven't found those RD16HHF1 parts except from the offshore sellers (who I have lost most confidence). I haven't made a deep search among the more reliable suppliers. The IRF parts are very inexpensive and apparently more robust so not a lot of motivation for the RD parts.
73,
Bill KU8H
bark less - wag more
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On 10/8/21 10:12 AM, Dean Souleles wrote: On Thu, Oct 7, 2021 at 06:04 AM, Ashhar Farhan wrote:
I have had considerable success with IRFZ24N. This was discovered
by W6JL for his ARRL Homebrew contest winning entry. The IRF510s,
idled back to provide 2 watts of drive can easily push a pair of
IRFZ24Ns for clean 50 watts power with 13.8v power supply.
Thanks Farhan. Now that I have built one amp I'm losing my fear of building another :).? A little bit of experience and great Elmer's like you, Pete and Bill goes a long way!
73,
Dean
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Dean:
Rex (QRPMe.com) also sells Mepads, which makes Manhattan style construction pretty easy for anyone. David Richards (AA7EE) uses them to take homebrew to an art form:
 Look closely and you'll see Hans LPF in the picture. He has more pictures on his website. Everytime I visit there, I want to throw rocks at my stuff!
Jack, W8TEE
On Friday, October 8, 2021, 09:51:22 AM EDT, Dean Souleles <dsouleles@...> wrote:
On Wed, Oct 6, 2021 at 08:31 PM, Tom, wb6b wrote:
Manhattan style, seems a perfect match for these cheap CNC routers
Yes, indeed.? Here are a few more boards I cut on the CNC.? And once the design is done it's a snap to knock out another one. Dean  
-- Jack, W8TEE
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I have two transverters and they both use the RD16HHF1. I have worked barefoot with them on both 50 and 70 MHz and I believe that he uses the same RD16HHF1 on the 144 MHz one
I built an amp almost identical to this one. I used the RD16HFF1 mosfets. It gave between 16 and 20W output from 80m to 10m, and 6W output on 6m. During sporadic E I worked several thousand km on SSB with the 6 watts, and it should be sufficient for a larger amplifier.? Here in the UK was also have &0 MHz (4 metres) but I didn't try these mosfets on that band.
Tony, G4CIZ
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He uses RD15HVF1 in the transverters as Sarmaji had recommended.?
On Fri, Oct 8, 2021, 8:40 PM Lawrence Galea < 9h1avlaw@...> wrote: I have two transverters and they both use the RD16HHF1. I have worked barefoot with them on both 50 and 70 MHz and I believe that he uses the same RD16HHF1 on the 144 MHz one
I built an amp almost identical to this one. I used the RD16HFF1 mosfets. It gave between 16 and 20W output from 80m to 10m, and 6W output on 6m. During sporadic E I worked several thousand km on SSB with the 6 watts, and it should be sufficient for a larger amplifier.? Here in the UK was also have &0 MHz (4 metres) but I didn't try these mosfets on that band.
Tony, G4CIZ
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Alex Netherton
Alex