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Title: I need help on replacing caps in viking ll Post by: KR4WI on October 30, 2006, 09:20:14 PM Hello Group: I have been replacing caps in my viking ll. I need to ask the folks with this tx if its ok to replace?
C7--with a ceramic disc C8--This is the big wax cap behind the oil filled cap, replace it with a orange drop Also mine is missing R33/R34 22 ohm, off the 807 plate caps, would they be a reason someone has taken these out? Thank you for sharing Matthew KR4WI Title: Re: I need help on replacing caps in viking ll Post by: ve6pg on October 31, 2006, 12:14:40 AM ...i see no problem...this shud werk ok...my viker doesnt have the 807 resistors ,and she werks fine...when u r in that thing,wire up a muffin fan to get the air moving inside....sucking out is best, there is no ventilation in that thing, except the perf top...not enuff....tim...sk...
Title: Re: I need help on replacing caps in viking ll Post by: The Slab Bacon on October 31, 2006, 08:59:15 AM Matt,
the resistors in the plate leads of the 807's are parasitic supressors / safety fuses. They can usually safely be eliminated. Just take a close look at your output waveform with a scope afterwards and be sure that there are no ultrasonic or subsonic audio parasitic oscilations in it. As far as replacing tubular caps with ceramics, as long as you have the same (or higher) working voltage as the original cap you should be good to go. Orange drops are fair game for replacing ANY of the old wax paper caps. They have kinda been the restoration standard for quite a few years, until they started getting a little pricey. The Slab Bacon Title: Re: I need help on replacing caps in viking ll Post by: W7SOE on November 07, 2006, 02:32:12 PM Take a good look at R13, this is the larger adjustable power resistor. These are often bad. I would replace it in any case. It serves two functions, it forms a voltage divider for the clamper circuit and it is also the HIGH VOLTAGE BLEED RESISTOR. (Yes I am yelling, bleeding off your high voltage is a good thing)
Mine ohm'd out ok but failed when powered so I had high voltage long after the unit was turned off. After replacement follow the directions in the manual to adjust you clamper circuit. (that is where you get to reach a long screwdriver into the rig with the HV on! :o Weeee! 73 rich W7SOE PS Newark has those resistors. Title: Re: I need help on replacing caps in viking ll Post by: KB2WIG on November 07, 2006, 03:17:20 PM "W7SOE PS Newark has those resistors." It never (almost) hurts to increase the power ratings of da bleeders..... RF Pfarts hawks the parasitic supressor/carbon comp resistors.. my old Comm. Electronic proff. got upset not seeing them 100 omers in applications... "Murpes law desin" .... You can use them 'yellow' tublers that Mouser has.... Polyproplean, about $0.40 a piece...... klc Title: Re: I need help on replacing caps in viking ll Post by: W1RKW on November 07, 2006, 04:46:21 PM Doesn't Timtron have a mod that takess this resistor out of the loop or separates it. I don't have the mod in front of me. Just something I think I remember.
Title: Re: I need help on replacing caps in viking ll Post by: KB2WIG on November 07, 2006, 05:00:26 PM In the Ranger mods... AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
"OH YES! I forgot to mention the famous 20K 50 Watt bleeder in the HV supply. This device functioned as an adjustable source of modulator screen voltage, clamp tube screen voltage and space heater to keep the rig warm on those cold winter nights. This device gets the axe!" The ramger mods allong with the Viking II mads are available on the AM Window button "above"; click on Modifications and there u r... klc |