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1. [Amps] 813 efficiency (score: 1): Author: "Mike Lord" <k4elv@bellsouth.net>; Date: Wed, 20 Feb 2013 14:18:04 -0600; Some time ago (maybe 2 years) there were comments filed on this site regarding increasing the efficiency of the 813 tube on 21 - 28 mhz. I've looked through my history of this group but failed to fin; /archives//html/Amps/2013-02/msg00165.html (7,125 bytes)
2. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Thu, 21 Feb 2013 11:15:41 -0500; Hi Mike, There was an article in an issue of QST (when it was still of the small-format, I believe), as well reference made in the large-format HANDBOOKS, regarding inserting a small coil in series w; /archives//html/Amps/2013-02/msg00173.html (9,396 bytes)
3. Re: [Amps] 813 efficiency (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Thu, 21 Feb 2013 08:18:40 -0800; The 813 has a relatively high output capacity (14 pf) so it can be difficult to get a reasonable Q on 28 mHz with practical components. It helps to use a vacuum capacitor with a lower minimum as the; /archives//html/Amps/2013-02/msg00174.html (9,293 bytes)
4. Re: [Amps] 813 efficiency (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Thu, 21 Feb 2013 14:13:16 -0500; Ive restored a 1954 QST cover project 813 TX and get around 60% Class C on 10M at 2200V and it increases to a bit over 70% on 80/40. Grid current on 10 and 15 isnt as high as Id like. A modified Glob; /archives//html/Amps/2013-02/msg00175.html (9,580 bytes)
5. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Thu, 21 Feb 2013 15:20:31 -0500; Oops...! What I MEANT to say, was 1/4" edge-wound copper ribbon, NOT 1.4"...! A coil of those latter dimensions would be deserving of MUCH more than just a PAIR of 813s!!! ~73~ de Eddy VE3CUI - VE3XZ; /archives//html/Amps/2013-02/msg00178.html (7,736 bytes)
6. Re: [Amps] 813 efficiency (score: 1): Author: Paul Baldock <paul@paulbaldock.com>; Date: Thu, 21 Feb 2013 17:21:32 -0800; I run a pair of 813's grid driven (grounded cathode). Plate voltage is about 2200V. I can get around 700W PEP on 15M and a little less on 10M. Because of the high output cap you need and L-PI. They r; /archives//html/Amps/2013-02/msg00180.html (8,704 bytes)
7. Re: [Amps] 813 efficiency (score: 1): Author: "Hsu" <hsu4qro@gmail.com>; Date: Fri, 22 Feb 2013 09:57:29 +0800; THis is a solution http://www.cqham.ru/HiFi_Contester_EX8A.htm Hsu -- From: Mike Lord Sent: Thursday, February 21, 2013 4:18 AM To: amps@contesting.com Subject: [Amps] 813 efficiency Some time ago (m; /archives//html/Amps/2013-02/msg00181.html (8,689 bytes)
8. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Fri, 22 Feb 2013 09:42:44 -0500; A solution, Hsu, That shall forever elude me--until I can learn to read Russian, or whatever language is being used on this site by the author! :o) ~73~ de Eddy VE3CUI - VE3XZ _______________________; /archives//html/Amps/2013-02/msg00186.html (8,363 bytes)
9. Re: [Amps] 813 efficiency (score: 1): Author: "Hsu" <hsu4qro@gmail.com>; Date: Fri, 22 Feb 2013 23:02:21 +0800; I can not read Russian too, I use google translate. Im planing to build a GU-81M G-G amplifer what coverage 160m to 6m by this way( only one tube, not a pair, I know If a pair ytube can not work on 6; /archives//html/Amps/2013-02/msg00189.html (8,845 bytes)
10. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Fri, 22 Feb 2013 10:09:33 -0500; THAT works, Hsu--many thanks! ~73~ de Eddy VE3CUI - VE3XZ _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2013-02/msg00190.html (8,293 bytes)
11. Re: [Amps] 813 efficiency (score: 1): Author: peter chadwick <g8on@fsmail.net>; Date: Fri, 22 Feb 2013 17:01:58 +0100; Another way is to abandon the pi network and run them in push-pull: this was how quite high efficiencies were obtained on the higher bands 'in the good old days' admittedly, in Class C. That wouldn't; /archives//html/Amps/2013-02/msg00191.html (8,217 bytes)
12. [Amps] 813 efficiency (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Fri, 22 Feb 2013 08:14:10 -0800; Hi Mike, There was an article in an issue of QST (when it was still of the small-format, I believe), as well reference made in the large-format HANDBOOKS, regarding inserting a small coil in series w; /archives//html/Amps/2013-02/msg00192.html (11,244 bytes)
13. Re: [Amps] 813 efficiency (score: 1): Author: ZL2AAA <zl2aaa@paradise.net.nz>; Date: Sat, 23 Feb 2013 09:17:22 +1300; From memory a GE Ham paper had this info and I think the answer was to tap the tuning cap along the 10m tank coil.Morrie Some time ago (maybe 2 years) there were comments filed on this site regarding; /archives//html/Amps/2013-02/msg00195.html (9,682 bytes)
14. Re: [Amps] 813 efficiency (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Fri, 22 Feb 2013 17:49:31 -0500; That was done in the bigger commercial rigs back into the 30's. Carl KM1H From memory a GE Ham paper had this info and I think the answer was to tap the tuning cap along the 10m tank coil.Morrie Some; /archives//html/Amps/2013-02/msg00199.html (11,271 bytes)
15. Re: [Amps] 813 efficiency (score: 1): Author: peter chadwick <g8on@fsmail.net>; Date: Sat, 23 Feb 2013 14:35:11 +0100; Carl, You can switch tank coils in push pull amps! I wonder how many people got killed bandchanging a BC610? 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@cont; /archives//html/Amps/2013-02/msg00205.html (7,991 bytes)
16. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Sat, 23 Feb 2013 07:22:45 -0500; Because the tuning on the lower bands was radically altered with it in, far & away removed from quoted "text book specs" for a pair of 813s in GG... Makes sense--good idea. Guess I shoulda considered; /archives//html/Amps/2013-02/msg00206.html (10,162 bytes)
17. Re: [Amps] 813 efficiency (score: 1): Author: Eddy Swynar <deswynar@xplornet.ca>; Date: Sat, 23 Feb 2013 10:01:55 -0500; Hi Guys, It absolutely gobsmacks me how some guys in this hobby would rather whip-out the ol' VISA card & spend literally HUNDREDS on power amplifier tubes, when the lowly ol' 813--paired with some t; /archives//html/Amps/2013-02/msg00208.html (8,704 bytes)
18. Re: [Amps] 813 efficiency (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Fri, 22 Feb 2013 20:23:31 -0500; I can just picture todays crop of hams changing tank coils (-; It might improve the gene pool tho.... Carl KM1H Another way is to abandon the pi network and run them in push-pull: this was how quite; /archives//html/Amps/2013-02/msg00209.html (9,647 bytes)
19. Re: [Amps] 813 efficiency (score: 1): Author: Bill Fuqua <wlfuqu00@uky.edu>; Date: Sat, 23 Feb 2013 10:32:21 -0500; There are other tubes out there that will do just as well that are quite inexpensive. 4-125 is one in particular which will do just as well as a 813 but has higher frequency response. They are usuall; /archives//html/Amps/2013-02/msg00211.html (10,041 bytes)
20. Re: [Amps] 813 efficiency (score: 1): Author: "Carl" <km1h@jeremy.mv.com>; Date: Sat, 23 Feb 2013 11:07:12 -0500; Oh, I know you can Peter, it is just a lot more complicated and might bring neutralization into the picture. I have never read any BC-610 statistics, wonder if they exist. My PP 250TH Class C amp in; /archives//html/Amps/2013-02/msg00213.html (9,365 bytes)

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