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References: [ +from:audioguy@q.com: 156 ]

Total 156 documents matching your query.

141. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sun, 20 Oct 2013 12:30:48 -0700
Thanks for the replies. Notables are: (1) Higher loading cap voltage (Gold Star Winner) (2) Loss, and what to do with the heat (3) Cost Thanks and 73, Jim N7CXI -- Assuming adequate core/wire sizing
/archives//html/Amps/2013-10/msg00359.html (9,177 bytes)

142. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Mon, 21 Oct 2013 02:31:49 -0700
Just to clarify, I used 1.6 for "K", which in Ian's spreadsheet is in the middle of the range for AB: Single 8877 4KV 625mA 60% efficiency "K" factor of 1.6 = 4000 ohms plate load impedance. Jim W7RY
/archives//html/Amps/2013-10/msg00375.html (12,908 bytes)

143. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Mon, 21 Oct 2013 12:09:28 -0700
Good point. If I lower the swing to 3800 and raise the current to 658mA to keep the same dissipation, the guesstimated plate load impedance drops to 3610 ohms. Lowering the Q to 10 then puts the load
/archives//html/Amps/2013-10/msg00383.html (12,081 bytes)

144. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Mon, 21 Oct 2013 12:21:21 -0700
Absolutely. I learned that trick from Carl, seems like a few hundred years ago. This design uses 3uH of "lead" inductance for just that reason. It raises the tune capacitance at 10M to a practical va
/archives//html/Amps/2013-10/msg00384.html (10,896 bytes)

145. [Amps] Microwave oven door glass - shielding? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Mon, 21 Oct 2013 15:15:32 -0700
Has anyone had experience using microwave oven door glass as a shielded viewport for an HF amp? Any ideas about attenuation at HF frequencies? I'm considering a three-tube 3500ZG amp as one of my win
/archives//html/Amps/2013-10/msg00386.html (7,110 bytes)

146. Re: [Amps] Microwave oven door glass - shielding? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Mon, 21 Oct 2013 21:26:43 -0700
Hi Ron, Has anyone had experience using microwave oven door glass as a shielded viewport for an HF amp? Any ideas about attenuation at HF frequencies? I'm considering a three-tube 3500ZG amp as one o
/archives//html/Amps/2013-10/msg00392.html (9,275 bytes)

147. Re: [Amps] Measuring IMD (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sat, 02 Nov 2013 12:50:48 -0700
Generating a two-tone test WAV file isn't especially difficult. If you have a PC with a semi-pro or pro external sound device, you can get 114dB or so SNR and very low distortion. The run-of-the-mill
/archives//html/Amps/2013-11/msg00021.html (13,204 bytes)

148. [Amps] Two-tone test file uploaded (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sat, 02 Nov 2013 14:23:55 -0700
Based on the recent IMD thread, I generated a 30 second two-tone test WAV file and posted it to a publicly-accessible server: http://www.n7cxi.com/public/two_tone_44.1_mono_24bit.wav The level is -1d
/archives//html/Amps/2013-11/msg00022.html (6,925 bytes)

149. Re: [Amps] Measuring IMD (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sun, 03 Nov 2013 06:24:57 -0800
A similar linearity-detecting scheme was used in a 3-1000Z design from the 1970 ARRL Handbook. "The SS-70 2-KW Amplifier", pp 204-208. It used diode RF detectors in the cathode and plate circuits, a
/archives//html/Amps/2013-11/msg00027.html (12,275 bytes)

150. Re: [Amps] Measuring IMD (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sun, 03 Nov 2013 08:05:31 -0800
A similar linearity-detecting scheme was used in a 3-1000Z design from the 1970 ARRL Handbook. "The SS-70 2-KW Amplifier", pp 204-208. It used diode RF detectors in the cathode and plate circuits, a
/archives//html/Amps/2013-11/msg00032.html (9,614 bytes)

151. Re: [Amps] Measuring IMD (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sun, 03 Nov 2013 10:48:31 -0800
In my mind, this side-thread with the diode detectors has more to do with loading and operating than testing. I wouldn't suggest it be used as a substitute for IMD testing a new design. Without any f
/archives//html/Amps/2013-11/msg00037.html (9,295 bytes)

152. [Amps] Chinese 15KV 2A rectifier modules? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Wed, 06 Nov 2013 16:37:15 -0800
Has anyone had any experience (good or bad) using the Chinese 15KV, 2A rectifier modules that were selling on eBay a while back? The part number printed on the side is PRHVP2A-20 . I bought a handful
/archives//html/Amps/2013-11/msg00082.html (7,252 bytes)

153. Re: [Amps] Chinese 15KV 2A rectifier modules? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Wed, 06 Nov 2013 18:09:46 -0800
Good idea, thanks. I have a variable DC supply and a handful of low-value, high-wattage resistors that should do the trick. 73, Jim N7CXI Of course, in normal use the current waveform would not be co
/archives//html/Amps/2013-11/msg00086.html (9,120 bytes)

154. Re: [Amps] Alpha chimneys (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Fri, 08 Nov 2013 15:15:19 -0800
It varies. With the Alpha 76A and variants, the chimneys just butt up against the perforated metal in the top of the case. With the 77* series, they're wrapped conically, (instead of a straight tube)
/archives//html/Amps/2013-11/msg00166.html (8,040 bytes)

155. Re: [Amps] Best source for Gigavac GH-1 ? (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sat, 09 Nov 2013 18:11:48 -0800
MaxGain is a GigaVac dealer. (for new, warranteed stock) They often have NOS Jennings, Kilovac etc as well. 73, Jim N7CXI http://www.gigavac.com/catalog/amateur-radio.html Mike, W1NR On 11/08/2013 03
/archives//html/Amps/2013-11/msg00187.html (8,862 bytes)

156. Re: [Amps] Screen current problem solved! (score: 1)
Author: Jim Barber <audioguy@q.com>
Date: Sat, 09 Nov 2013 18:47:50 -0800
Thanks, Carl... Here I was minding my own business, eating a cookie and then I read that. What a mess. "cruise gracefully through the flotsam" ?? 73, Jim N7CXI On 11/9/2013 6:43 PM, Carl wrote: But o
/archives//html/Amps/2013-11/msg00191.html (9,682 bytes)

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