|
Title: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: AE2EA on March 24, 2022, 08:50:25 AM Two years ago I posted here asking for advice on converting my RCA-BTA250M to the ham bands. A couple of members suggested scrapping the RCA output network and putting in a Pi network. It took me a year to get around to that, but it was the way to go. Thanks for the advice!
Here's a short video about the project: https://youtu.be/3o6MokfWLHk 73, Mark ~ AE2EA Title: Re: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: DMOD on March 24, 2022, 12:58:23 PM Two years ago I posted here asking for advice on converting my RCA-BTA250M to the ham bands. A couple of members suggested scrapping the RCA output network and putting in a Pi network. It took me a year to get around to that, but it was the way to go. Thanks for the advice! Here's a short video about the project: https://youtu.be/3o6MokfWLHk 73, Mark ~ AE2EA Can you give the values of the Pi-net components as they may help other's doing a conversion. thanks, Phil - AC0Ob Title: Re: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: AE2EA on March 25, 2022, 09:33:42 AM No Problem Phil.
For a 2900 ohm plate load: Tank capacitance : 250pf variable in parallel with 150pf fixed. Tank inductor: 23 uH Loading capacitance: 2000pf variable in parallel with 2000pf fixed. FYI, RCA Ham Tips volume 14, number 2, dated July-August 1954 is devoted to Pi-networks, and has a chart for impedances of common tubes at various voltages, and a chart for component values to match various operating impedances. A very handy tool to have. It’s available here: http://n4trb.com/AmateurRadio/RCA_Ham_Tips/issues/rcahamtips1402.pdf 73, Mark ~ AE2EA Title: Re: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: W3GMS on March 25, 2022, 03:36:33 PM Very nice job Mark.
Joe-GMS Title: Re: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: DMOD on March 26, 2022, 02:07:02 PM No Problem Phil. For a 2900 ohm plate load: Tank capacitance : 250pf variable in parallel with 150pf fixed. Tank inductor: 23 uH Loading capacitance: 2000pf variable in parallel with 2000pf fixed. FYI, RCA Ham Tips volume 14, number 2, dated July-August 1954 is devoted to Pi-networks, and has a chart for impedances of common tubes at various voltages, and a chart for component values to match various operating impedances. A very handy tool to have. It’s available here: http://n4trb.com/AmateurRadio/RCA_Ham_Tips/issues/rcahamtips1402.pdf 73, Mark ~ AE2EA Thanks Mark for the cookbook article. In my case I use the Wingfield (W5FD) equations programmed in MatLab with the Terman correction. "New and Improved Formula's for the Design of Pi and Pi-L Networks," QST, aug. 1983. Phil - AC0OB Title: Re: The Pi Network Upgrade for my 160 Meter AM Transmitter Post by: F6BGV on April 26, 2022, 06:44:51 PM Hello ! AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
The Pi-Network Tank Design in QST 09/1958, is more convenient ! Best 73 John P.S: 500 for Class C / 600 for Class B / 700 for Class A |