[Elecraft] SS30DV feedback OT
Very impressive indeed. Pre-distortion will hopefully be made available as a option for the K3 in the future. That would be a superb option if it does become available. What these results however do confirm is that pre-distortrion is worth implimenting and that it does work very well. The work by N1JEZ also confirms that current LDMOS amplifiers do not have acceptable levels of IMD performance, especially at higher powers. In my opinion based on the IMD data by N1JEZ they are inherently very dirty. I have not seen a working example of a LDMOS amplifier that I would consider clean when compared against even a pair of 3-500's. I have studied the NXP datasheets for these devices and have found that LDMOS devices like the BLF574 can produce excellent IMD performance. The BLF574 according to the data sheet at 200 watts of ouput and 1200ma of idle current is capable of -40dbc 3rd order IMD performance. I have not seen data for the higher order products but this figure is good. I have been working on a homebrew LDMOS solid state amplifier for my K3 and have not decided what devices I will use in the design. I do have a MRF150/EB104 amplifier that works very well and it has very good IMD performance. I would like to try these LDMOS designs. I wont however waste effort on a marginally poor IMD PA. Homebrewing is a lot of effort and I cant see the point of spending dollars and time on any project when it does not meet acceptable technical standards like IMD performance.. I wonder when we will see pre-distortion in a commercial ham radio tranceiver outside of the experimental devlopments like HPSDR. Is Elecraft working on a pre-distortion implimentation? 73 Craig "With bias, 12V transistors are class B or AB, not C. See http://flarc.net/eme-info/PDF/N1JEZ-2.pdf. Ignacy, NO9E" __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] SS30DV feedback OT
With predistortion coming sooner or later to mainstream radios, higher PA voltage for 100W is dead issue. Ignacy -- View this message in context: http://elecraft.365791.n2.nabble.com/Re-SS30DV-feedback-OT-tp7608653p7608665.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] SS30DV feedback OT
With bias, 12V transistors are class B or AB, not C. See http://flarc.net/eme-info/PDF/N1JEZ-2.pdf. He describes an amp changed to Class B (very low bias for little heating). Regular IMD3 -22db. After predistortion -55db. Plus extra db in additional power power. All for a cost of feedback + some programming. With predistortion we can get more power (drive closer to saturation) with less heating (higher efficiency and lower quiescent current) and less IMD. All for a cost of hardware feedback + programming. I am all for 50V (or higher) for high power amps. Ignacy, NO9E -- View this message in context: http://elecraft.365791.n2.nabble.com/Re-SS30DV-feedback-OT-tp7608653p7608673.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] SS30DV feedback OT
On 10/3/2015 10:14 AM, Ignacy wrote: With predistortion coming sooner or later to mainstream radios, higher PA voltage for 100W is dead issue. Ignacy Higher voltage PA and predistortion are completely separate items. Even with predistortion, good engineering principles mean higher voltage transistors one should be used for 100W class rigs. Most 50 or 60 W "12V" transistors are class C devices (a pair for "100 W") ... predistortion is not going to make class C finals clean enough for reasonable SSB. Modern "12V" radios are 10 dB or more dirtier than older generation tube transceivers. 73, ... Joe, W4TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] SS30DV feedback OT
Brain yes I recall tubes and the multiple power supply requirements. I even designed to a few. I also remember how rough it was to do mobile power supplies where the HV came from either vibrators or dynamotors. Then it was transistors and everything went to 13.85V. But transistor output tanks were never the same because transistor class C tank coils couldn't handle the current so we went to low Q tanks with class B outputs. Around 2002-2003 there was SAE group called 42Volt. They stated by 2007 that the AC compressor, water pump, and power steering would be electrically driven and therefore the automotive industry must switch to 42 volts (basically three 12v batteries in series). I couldn't wait for 42 volts to work its way into ham radio. By 2007 the group had disbanded. My guess is hybrids killed 42V because they wanted to keep the accessories powered by the engine and not the hybrid battery. The K2 and K3 are dual desktop and mobile radios. Perhaps it is time for a desktop only radio with HV FET finals with a built in power supply. Also a 42V mobile with its own add-on alternator and quiet down converter for the receiver and LEDs. 73 Fred, AE6QL -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of brian Sent: Friday, October 2, 2015 1:12 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] SS30DV feedback Fred, I'm a fan of higher voltage -- perhaps 24 or 40 volts so that PA transistors can produce cleaner signals. Doing so reduces any IR drop on power supply wiring by a factor of 2 or 3. KISS. IC's are going to lower and lower voltages. Multiple circuits within boxes require a menagerie of voltages. One is faced with having to generate more heat in regulators dropping 40 volts to 12, maybe 5, 3.3 and 1.6 V. Perhaps the era of efficient multivoltage power supplies with multiple wires for multiple voltages will return. (Remember filament ,plate, screen and grid voltage power supplies in days of yore? Guys generally didn't mistakenly hook up the 3500 V B+ wire to the filaments..) 73 de Brian/K3KO On 10/2/2015 19:54 PM, Fred Townsend wrote: > Joe, I am familiar with Kelvin sensing, otherwise known as 4 wire or remote > sensing. Its advantages are probably outweighed by the risks of misconnecting > and filtering needed for RF environments. With <4 feet of 10 ga wire I don't > see significant voltage drops. I prefer KISS. > 73 > Fred, AE6QL > > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Joe Subich, > W4TV > Sent: Friday, October 2, 2015 12:33 PM > To: Eric Swartz - WA6HHQ, Elecraft; elecraft@mailman.qth.net > Subject: Re: [Elecraft] SS30DV feedback > > On 10/2/2015 12:33 PM, Eric Swartz - WA6HHQ, Elecraft wrote: >> The SS30DV has +/- bolt terminals on the rear. The K3S is supplied >> with a power cable using ring lugs for these bolts on one end, and an >> APP connector for the K3S on the other. > Very good! How about remote sensing terminals/connector on the next > iteration of the K3/K3S - ideally on the KPA3 ? > > 73, > > ... Joe, W4TV > > > On 10/2/2015 12:33 PM, Eric Swartz - WA6HHQ, Elecraft wrote: >> The SS30DV has +/- bolt terminals on the rear. The K3S is supplied >> with a power cable using ring lugs for these bolts on one end, and an >> APP connector for the K3S on the other. >> >> One other note, at the 100W operating level, we do not see any >> significant voltage drop across the APP conn. >> >> 73, >> >> Eric >> /elecraft.com/ >> >> On 10/2/2015 8:53 AM, Joe Subich, W4TV wrote: I prefer a PS with black and red connectors so I can connect any cable and don´t worry about connectors. >>> Quality *bolt* terminals will generally show less voltage drop in >>> transmit than the wiping contacts like PowerPole connectors. That >>> is particularly true when the PowerPoles are not assembled correctly >>> and there is less than full pressure between the wiping contacts. >>> >>> I would prefer any power supply and transceiver with greater than 5A >>> current rating use 1/4" or 3/8" stub bolted connections like the >>> Astron RS-35A/RS-35M and potentially provide a voltage sense >>> connection to support load sensing for supplies that support it or >>> can be modified to support it. >>> >>> 73, >>> >>> ... Joe, W4TV >>> >>> >>> On 10/2/2015 11:33 AM, Jorge Diez - CX6VM wrote: Hello Matt Thanks for the Info. I have two SEC-1235M and I hate the terminal screws, I think they are aluminum and I broke them if removing power cable too much times I prefer a PS with black and red connectors so I can connect any cable and don´t worry about connectors. Thanks! Jorge CX6VM/CW5W -Mensaje original- De: Matt Zilmer [mailto:mzil...@roadrunner.com] Enviado el: viernes, 02 de
