Re: IRF510 amplifier failures
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Well it’s this way.? You can either spend a little more on the transistor (with the nice input characteristics) and design with minimal parts (e.g. one set of broad band impedance matching transformers and bias network) to work over a large frequency range (1-54 MHz)…. Or you use a cheap motor switch like the 510 and live with the gain roll-off from mismatch (large del C / del Freq) with a fixed set of broad band I/O transformers…. OR you spend more $$$ to build band switchable compensation networks to improve the matching (Can be bulky and expensive but not always).? Pay me now of pay me later.? Many commercial SS Amps that cover 1-54 MHz complete still utilize some sort of compensation network in them to cover the large frequency range and it’s not apparent to the user… even with very good RF transistors (sometimes driven by the transformer material).?? All depends on the part.? Best to Simulate from the S params first.? It will tell you a lot. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? ? email:? bill@... ?
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From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of philip yates
Sent: Saturday, January 27, 2018 10:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] IRF510 amplifier failures ? So if they are " real RF transistors" probably worth the extra then ? ? On Sat, Jan 27, 2018 at 1:36 PM, K9HZ <bill@...> wrote: I don’t think it’s so much a matter of if they will work or not.? Both will work fine at 50 MHz (and above actually)… the issue is that the RD15HVF1 is a little flatter across the spectrum and from that perspective easier to design around and match.? I use them all the time and they are very easy parts to make work.? A pair will easily put out 30 watts 1-54 MHz if the rest of the design is correct. ? I’ve been thinking about and have had requests for a nice linear amplifier for the uBITx and these parts are cheap enough to use for that purpose too.? I originally designed one using two RD70HVF1 parts but the cheapest I’ve found them is $18 each.? Not a show stopper but the little brothers are cheaper.? If The parts were under $15 in large quantity, it would be a no brainer.? The auto tuner must be finished first though.? Oh, did I mention, the RD series devices are real RF transistors? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? ? email:? bill@... ? From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Lawrence Galea
Sent: Saturday, January 27, 2018 3:34 AM ? I was thinking about the RD15HVF1 so that it would be easier for people who want to try 50MHz and perhaps 70MHs where available with suitable mods to the μbitx. The RD16HHF1 appears to be? used in the Ukraine transverters as a PA in the 50MHz, 70MHz and 144 MHz transverters while the RD15HBF1 appears to be used in the 222MHz and 432MHz transverters.? I have the 50MHz and 70MHz transverters and they do work.
Two years ago I worked more than 40 stations on 70MHz (see my log on QRZ dot com) with a simple dipole at about 4M high on the roof fed with some 50 feet of RG58 coax. Last year I built a 5 element LFA Yagi for 70MHz but didn't have time to get on the air.? ? On Sat, Jan 27, 2018 at 3:41 AM, James Lawrie <lawriejk@...> wrote: Hello, That’s why I bought 10 ea... for the uBitxs I’ll probably get the others rated at over 30 MHz. Always nice to stock up on useful parts. Out of all listed on there website what would you recommend for HF/VHF use?
On Jan 26, 2018, at 19:56, K9HZ <bill@...> wrote:
The RD15HVF1 has a bit of a flatter input capacitance curve with frequency so its easier to keep constant gain over 1-54 MHz… but the RD16HHF1 is certainly a worthy part too.? Oh, did I mention, they are both real RF transistors? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? ? email:? bill@... ? ? On same site I found these, made for 30 MHz?RD16HHF1. Sooo I bought 10 of them, plan to try in Bix40 first. Data sheet even shows a reference amp design, and they are 12 volt like the other one. If it works I’ll let everyone know. ?
On Jan 26, 2018, at 11:32, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
The RD15HVF1's should be operated at not much more than 12v.
At 12v, the IRF510's would survive just fine with no antenna connected.
That's an infinite VSWR.
So not obvious that this is a solution to blown FET's.
Though I do think the the Ids curves go up more slowly as Vgs increases on the RD15HF1's,
which makes RV2,RV3 not so touchy.
And the RD15HF1's might be easier to drive at 30mhz.
If you do swap them in, let us know how much power you get at 30mhz.
Jerry, KE7ER
On Fri, Jan 26, 2018 at 03:54 am, KD8CGH wrote: Wouldn't it be better to change to a RD15HVF1 for high VSWR
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