- 1. [Amps] 8877 Max Grid Current (score: 1)
- Author: vk3hz@wia.org.au (David Smith)
- Date: Tue, 18 Jun 2002 10:19:22 +1000
- I'm currently building a 2m 8877 linear amp, based on the K1AGB design. For my metering/protection cicuit, I need to know the maximum safe grid current that an 8877 can handle. It's not specified in
- /archives//html/Amps/2002-06/msg00128.html (7,475 bytes)
- 2. [Amps] 8877 Max Grid Current (score: 1)
- Author: vk3hz@wia.org.au (David Smith)
- Date: Tue, 18 Jun 2002 15:19:55 +1000
- Rich, My data sheet shows 25 watts which works out to be a grid current of around 380mA. This seems too high. I fear that it may not be that simple (mixing AC and DC characteristics) although my tube
- /archives//html/Amps/2002-06/msg00133.html (8,943 bytes)
- 3. [Amps] Filter Capacitors - Oil Filled vs. Electrolytic (score: 1)
- Author: vk3hz@wia.org.au (David Smith)
- Date: Sat, 29 Jun 2002 21:31:34 +1000
- I'm on to building the HV PSU for the 8877. I have 2 alternatives for filtering - a used but good 54uF 4.2kV oil-filled Maxwell or a string of 10 new 470uF 450V electrolytics (with 45K 10W equalisers
- /archives//html/Amps/2002-06/msg00265.html (7,017 bytes)
- 4. [Amps] Defibrulator Caps as Filter Caps (score: 1)
- Author: vk3hz@wia.org.au (David Smith)
- Date: Sun, 30 Jun 2002 10:27:09 +1000
- Turns out that this capacitor is from an HP defibrulator. There seems to be a question about whether a defib cap can handle continuous PSU filter duty. It may need to be derated. Any comments? Regard
- /archives//html/Amps/2002-06/msg00276.html (8,126 bytes)
- 5. [Amps] Input Matching for 8877 on 2m (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Fri, 12 Dec 2003 12:04:15 +1100
- I'm building an 8877 amp for 2m - K1AGB grounded-grid stripline design - and I'm having problems with the proposed input matching circuit (which is the same as for the more popular W6PO design). The
- /archives//html/Amps/2003-12/msg00183.html (7,355 bytes)
- 6. Re: [Amps] GS-35B (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Tue, 27 Jul 2004 09:08:52 +1000
- Hi John, The GS-35b is designed for G-G use (the grid ring doubling as a chassis mounting point), and for a reason. If you try to use a GS-35b (or any triode) in a grid-driven configuration on 2m, yo
- /archives//html/Amps/2004-07/msg00207.html (7,356 bytes)
- 7. Re: [Amps] Plate tank for 144 MHz using 8877 (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Sat, 9 Oct 2004 16:36:51 +1000
- Hi Bill, You should also look at the K1AGB design that appeared in the ARRL manual in the mid 80's. He deliberately designed it to be easy to build using basic workshop tools. It uses a stripline ano
- /archives//html/Amps/2004-10/msg00110.html (8,438 bytes)
- 8. [Amps] K1AGB 8877 2m Amplifier Article (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Wed, 13 Oct 2004 11:09:40 +1000
- If anyone else is interested in the K1AGB 8877 2m PA article, you can download it from my web site at: http://users.bigpond.net.au/dwsmith/k1agb%20article.pdf Regards, Dave VK3HZ ____________________
- /archives//html/Amps/2004-10/msg00194.html (6,631 bytes)
- 9. [Amps] Dual Band 2m / 70cm PA (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Thu, 30 Dec 2004 22:51:29 +1100
- Does anyone know of a design for a valve PA that covers both 2m & 70cm using the same tube? I'm thinking about a compact PA for these two bands, possibly using a HV PSU from a Panasonic "Inverter" mi
- /archives//html/Amps/2004-12/msg00396.html (6,645 bytes)
- 10. Re: [Amps] Liquid Cooling Systems (score: 1)
- Author: "David Smith" <vk3hz@wia.org.au>
- Date: Fri, 11 Mar 2005 16:44:17 +1100
- I'm certainly very interested in this discussion as I'm contemplating a water-cooled 23cm amp project shortly. One thing that you do need to consider in cooling a tube amp is the conductivity of the
- /archives//html/Amps/2005-03/msg00278.html (7,031 bytes)
- 11. Re: [Amps] One PS, many amps (score: 1)
- Author: David Smith <vk3hz@wia.org.au>
- Date: Fri, 07 Oct 2005 10:08:59 +1000
- I run amps for 2m and 70cm (both GG triodes) off a common supply. Like the original poster (Dino) is proposing, mine is set up so that only one amp can be keyed at any one time. Mine uses common ano
- /archives//html/Amps/2005-10/msg00166.html (7,110 bytes)
- 12. Re: [Amps] Switching Power Supplies (score: 1)
- Author: David Smith <vk3hz@wia.org.au>
- Date: Sat, 15 Jul 2006 11:25:09 +1000
- I use a switching supply to run the filament of a GS35b in a 70cm amp for several reasons: 1. The filament volts should be backed off a little to allow for additional heating due to back-bombardment
- /archives//html/Amps/2006-07/msg00406.html (8,027 bytes)
- 13. [Amps] Inverter Microwave HV Supply (score: 1)
- Author: David Smith <vk3hz@wia.org.au>
- Date: Wed, 23 Aug 2006 12:12:13 +1000
- Hi all, For some time now, I've been investigating the use of a high voltage inverter power supply from a Panasonic microwave oven for powering a compact, light-weight linear amplifier. The results s
- /archives//html/Amps/2006-08/msg00619.html (6,995 bytes)
- 14. Re: [Amps] Inverter Microwave HV Supply (score: 1)
- Author: David Smith <vk3hz@wia.org.au>
- Date: Thu, 24 Aug 2006 08:03:02 +1000
- Several people have reported problems accessing the file. Try dropping the www - i.e. users.bigpond.net.au/dwsmith/hv_inverter.pdf I haven't noticed any interference from the oven here (or the wife).
- /archives//html/Amps/2006-08/msg00628.html (7,657 bytes)
- 15. Re: [Amps] Inverter Microwave HV Supply (score: 1)
- Author: David Smith <vk3hz@wia.org.au>
- Date: Thu, 24 Aug 2006 15:17:07 +1000
- Hi Will, There's little doubt that the input and output filtering is light-on. However, it's not a lack of regulation that's the problem - it's that the PSU controller regulates for constant POWER ou
- /archives//html/Amps/2006-08/msg00634.html (9,051 bytes)
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