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Title: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: W4AMV on August 09, 2012, 04:51:41 PM I am finally pulling all the parts together for a CW (maybe phone) 250-500 W linear, or just class-C. Following the KISS tactic I was going to go the route of GG. However, my exciter is a homebrew solid state unit with a Po of 50 W. I plan on visiting the local University library this weekend and was looking for suggestions for past QST treatment-articles for the tubes mentioned above in the post. Key is the power supply and in hand I have a range of xmfr's from 450 V at 1 A to 1500 V at 300 mA. Again, QST-reading material suggestions are greatly appreciated.
Alan Title: Re: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: Pete, WA2CWA on August 09, 2012, 05:11:55 PM Did you try this for starters. There is info on AM linears and a 813 transmitter where you might be able to derived some ideas. http://www.arrl.org/am-phone-operating-and-activities
Also: Jul 1954 - QST (Pg. 20) 813s in a High-Power Linear; Nov 1961 - QST (Pg. 56) Single-Band Grounded-Grid Linears Title: Re: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: KM1H on August 09, 2012, 05:14:08 PM The 4-250/400 will have the highest power gain and work well with 50W in GG. You may need an input network to get best power transfer. About 2000-2500V would be better. A pair of 4E27A's would do OK at 1500V but 2000V and up is mo betta.
A pair of 813's also like higher voltage, and 50W will just about work with a pair of 811A's and be straining at 300W for CW, forget AM. Carl Title: Re: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: kb3ouk on August 09, 2012, 09:08:31 PM If you are going with CW-only, class C will work fine amplifying that, no need to build a linear stage for just CW.
Title: Re: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: WA1GFZ on August 10, 2012, 11:07:00 AM 4-250 / 4-400 are better RF tubes. I used to run class B in CW with my 4-1000A linera. It will require more drive though but efficiency is higher.
813 will work Title: Re: Suggestions on QST or ARRL designs from the 50-60's for 811, 813, or 4-250 PA Post by: W4AMV on August 10, 2012, 11:55:29 AM All good info. Thanks! I think my challenge is going to be the HV supply. The 450 V xmfr is easily 1A plus. Was part of an overhead crane system power supply. I was going to double to 1000 but that still is really to low and even the 1500 V to low as well. At this point if I use what is in hand and go with CW only, I think a pair of 811s are the best bet. I have 4 of them but I don't have the filamnet supply current to support all 4... 2 is the option now. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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