开云体育

Single Messages Topics Expanded Polls

Re: FL-2100Z Mods

Bob All Messages By This Member #40795 Akek, That worked! Thanx. My Kenwood has a soft start in it already (Kessler). My Henry (2K-3) about once every three months will trip the breaker when turned on. I can live with that I guess. The amp was built in 1968 so I guess it can stay the way it is. Plus for my "test" amp, I use the MFJ external step start, ICP-240. I think the Henry is about maximum for that MFJ. So you're using the NTC in place of a resistor in the soft start. I never thought of that but obviously it works. The NTC in my Astron RS-50 is always in the circuit. 7 years or so used just about everyday and it's obviously holding up. Yep, different than an amp though. 73, Bob W4JFA toggle quoted message Show quoted text On Mon, Dec 9, 2024 at 4:33?PM Alek Petkovic via <vk6apk=[email protected]> wrote: Hi Bob Search for 100A 4000W High-Power Soft Start Circuit Power Board for Class A Amplifier Amp 73, Alek. On 9/12/2024 10:00 pm, Bob via wrote: Alek, Angus, I couldn't make those ebay numbers work but if you do a search on ebay for "NTC resistor" you get several. I had to use one in my 50 amp Astron (RS-50) linear power supply. It would sometimes trip the breaker. at start up The one I used is... SL322R025. It solved?the problem. It's been at least 7 years with no problems. Here's a link... I originally got the info from "repeater builder"? 73, Bob W4JFA On Sun, Dec 8, 2024 at 10:49?PM Alek Petkovic via <vk6apk=[email protected]> wrote: G'day Angus. Sorry for the delay. I missed your email and I'm just cleaning up my emails and noticed this one. Yes, the NTC works. I use them in this form for a lot of amps that I build. See Ebay Item number 402565661699. They are compact and work extremely well. I've never bothered with soft starts for the little Yaesu amps, as all the Yaesus I've worked on, have excessive filament voltage at the filament pins when connected to our AC mains. A low value of resistance made up of 5W wirewound resistors in parallel in series with the filaments brings the volts back from around 6.9 - 7.0V back down to the nominal 6.3V. This resistance, usually around 0.15 Ohms, also provides a measure of inrush protection to the filaments. This is very important when using Chinese valves, which hate excessive volts on the filament. Cheers from sunny Binningup, Western Australia. Alek VK6APK On 16/11/2024 5:06 am, AngusGM6AGC via wrote: Hi Alek, I trust you are well. Have you done the step start mod ?“A simple but effective delay can be done with an NTC resistor. The primary winding of the transformer is only a few Ohm, so that a 1Ohm/20A NTC is sufficient to limit the large momentary switching currents of uncharged HV elco's and cold filaments.” Is it effective? Other soft step start arrangements seem more complex. I look forward to hearing from you. Best wishes Angus ?

View All 15 Messages

#40795

Join [email protected] to automatically receive all group messages.