thats probably wire loss, not your power supply... it needs bigger cables... Measure voltage at the power supply for a true reading...
Carl Vangsness wrote: > The > RS35M will drop from 14.2 to 13.8 under full load (measured with DVM at > SDR1000 power terminals). I had to open it up to run the output voltage > up when I first got it. But no problems in that area since installing > the RS35M. > > 73, Carl WC0V > > W5CUL wrote: > >> Gerald, >> >> Yes, I understand the relationship between power, voltage, and impedance. >> And I do not disagree that a small voltage drop can affect the radio during >> transmit, even to the point of causing transmitted distortion. My question >> regarding where the Vdc reading is being taken from and the methodology used >> by the on board volt metering system in the 5000A is in response to Robert >> Cleve's observations while testing into a dummy load at 100W; see thread >> below. He is seeing a .4Vdc drop reported by the 5000A which would seem >> pretty high given he is using a 50A power supply and is presumably using the >> appropriate gage cable. I would have suspected that the reading he is >> seeing may be off a little, which is why I asked the question about the >> onboard Vdc meter system and suggested using an O-Scope attached to the DC >> input right at the radio. The other thing that troubles me about Robert's >> reading is that he reports the Ammeter on his Astron was only showing a 7A >> draw during his test. Again, I would suspect the meter on the Astron Power >> Supply is not being entirely accurate as he should be seeing ~20 to 21A draw >> during a 100W key down. >> >> So now Robert's measurements prompted me to look at my 5000A using the on >> board meter just to see what mine says. Below are the measurements: >> >> Idle: 13.8 >> 5W: 13.7 >> 10W: 13.6 >> 20W: 13.6 >> 50W: 13.5 >> 75W: 13.5 >> 100W: 13.4 >> >> The above measurements were taken using the built in metering system >> (CTRL-SHIFT-I), using the Tune function, output power monitored and adjusted >> using an on off board power meter. The power supply is an Astron RS-35M. >> Not as beefy as Robert's, but should hold up to a ~20A draw. >> >> Here are the same measurements using a DVM connected at the power supply: >> >> Idle: 13.87 >> 5W: 13.85 >> 10W: 13.85 >> 20W: 13.85 >> 50W: 13.84 >> 75W: 13.83 >> 100W: 13.83 >> >> Here are the same measurements using a DVM connected at the radio. Keep in >> mind that I am only monitoring one of the Vdc lines: >> >> Idle: 13.84 >> 5W: 13.77 >> 10W: 13.75 >> 20W: 13.73 >> 50W: 13.68 >> 75W: 13.66 >> 100W: 13.63 >> >> All of this seems to point towards a voltage drop along the DC power chain >> starting with the power supply, a larger drop seen across the OEM supplied >> power cable, and another large drop where the built in voltage meter system >> in the 5000A is taking its reading. >> >> Thank you, >> >> Mike >> W5CUL >> >> >> -----Original Message----- >> From: Gerald Youngblood [mailto:[EMAIL PROTECTED] >> Sent: Thursday, July 10, 2008 4:22 PM >> To: 'Flexradio'; 'Mike Schlamp' >> Subject: RE: [Flexradio] Just how much DC Power Supply sag is acceptable? >> >> Remember that power is the ratio of voltage squared over impedance. At >> 13.8V a small voltage difference can make a big effect on PA compression >> (i.e. distortion). >> Gerald >> >> >> Gerald Youngblood, K5SDR >> President >> FlexRadio Systems >> 13091 Pond Springs Rd. #250 >> Austin, TX 78729 >> Phone: 512-535-4713 >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of Rob Sherwood >> Sent: Thursday, July 10, 2008 4:08 PM >> To: Robert Cleve; Flexradio; Mike Schlamp >> Subject: Re: [Flexradio] Just how much DC Power Supply sag is acceptable? >> >> I don't know how the 5000 is affected by a small drop in Vcc, but the K3 3rd >> order IMD degrades significantly with 1/2 volt drop in the cable. >> >> >>>>> Mike Schlamp <[EMAIL PROTECTED]> 7/10/2008 2:15 PM >>> >>>>> >> Does anyone know, when using the built in voltage meter on the 5000A, where >> in the DC power chain is it taking the reading, and how it is doing that >> function? That may have some significance in what you see. But using an >> O-Scope right where the DC power comes into the radio will tell all. >> >> Mike >> W5CUL >> >> Robert Cleve <[EMAIL PROTECTED]> wrote: >> I use an Astron RS-50M DC supply with my 5000A. With 100 watts tune >> carrier into a dummy load the supply voltage drops from 13.7 to 13.3 DC >> Volts as seen using the radio's cntrl-shift-I window. The Astron's Amp meter >> shows 7 amps under the 100 watt load and the Astron's Volt meter doesn't >> budge at all from 14.5 VDC under load. Is this acceptable? I am using the >> standard DC power cable that came with the Flex 5000A. >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex ( http://mail.flex/ >> )-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail ( http://www.mail/ >> )-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kb.flex ( http://kb.flex/ )-radio.com/ Homepage: >> http://www.flex ( http://www.flex/ )-radio.com/ >> >> >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex ( http://mail.flex/ >> )-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail ( http://www.mail/ >> )-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kb.flex ( http://kb.flex/ )-radio.com/ Homepage: >> http://www.flex ( http://www.flex/ )-radio.com/ >> >> >> >> >> -- >> If this email is spam, report it here: >> http://www.onlymyemail.com/view/?action=reportSpam&Id=ODExMjI6Njg2NjE5ODE2On >> JvYkBuYzBiLmNvbQ%3D%3D >> >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kb.flex-radio.com/ Homepage: >> http://www.flex-radio.com/ >> >> >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kb.flex-radio.com/ Homepage: >> http://www.flex-radio.com/ >> >> >> > > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kb.flex-radio.com/ Homepage: > http://www.flex-radio.com/ > > > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
