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Title: Need advice on RF choke replacement Post by: WO4K on August 14, 2016, 08:35:44 AM Application: DX-100B final amp, RF choke and parasitic chokes for the 6146 tubes.
Symptom: Transmitter output is low (70 watts on AM when I normally get 125). Plate reads a max of 75 milliamps on the meter (spec calls for 150 ma). Grid and voltage readings are good (400v). Observation: Replaced both 6146 tubes (both tested marginal under load) and noticed the parasitic choke resistors are burned and test bad on the VOM, RF choke appears toasty, too. So I want to replace the RF choke (part # 45-4 in the manual) and parasitic chokes for the 6146 tubes in the final. Thought I was going to have to home-brew my own parasitic chokes, but found the exact replacement parasitic chokes at Surplus Sales of Nebraska. They also have an RF choke that I may be able to use, but I just need to check with you guys to be sure. The manual calls for 1 mh at 500 ma. The one available at SSN is 1.1 mh at 1 amp. So it is within + - 10% on the inductance. Good to go. But the amperage of the the SSN choke is double that of the 500 ma spec in the manual. I want to be sure the amperage factor is not critical. I suspect it is similar to the wattage in resistors or voltage in capacitors: More is OK, less is not OK. Advice, please. Title: Re: Need advice on RF choke replacement Post by: W7TFO on August 14, 2016, 06:28:23 PM One Amp is a lot more reliable than the original. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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