- 321. Re: [Amps] Alpha 78 B- Resistor (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sat, 24 Jan 2004 06:05:11 -0800
- ** GLOBAR-KANTHAL's Type SP resistors are superior to garden-variety wirewound resistors for glitch service. (phone order # 716 286 7610) ** Amplifiers with tubes that utilize tubes with gold-plated
- /archives//html/Amps/2004-01/msg00255.html (8,946 bytes)
- 322. Re: [Amps] Drake L7 in need of TLC? Advice please! (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sat, 24 Jan 2004 17:11:56 -0800
- ** replacing all of the diodes with the same type number is good engineering practice. ** 200 - 500 uF. 450v units should be ok. ** Equalizing resistors are not good engineering practice. ** No, but
- /archives//html/Amps/2004-01/msg00259.html (9,547 bytes)
- 323. Re: [Amps] Tough valves? (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sun, 25 Jan 2004 04:51:11 -0800
- ** Probably the most rugged valves/tubes around are those with thoriated-tungsten mesh filaments. Examples are the 8170R/4cx5000R, 3cx1000A7, 4cx1500A, the 4cx10,000J, et cetera. However, shipping su
- /archives//html/Amps/2004-01/msg00266.html (7,849 bytes)
- 324. Re: [Amps] HV SAFETY QUESTION (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sun, 25 Jan 2004 07:08:24 -0800
- ** Does anyone know of a case where the stored charge on the filter C proved to be deadly? _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contestin
- /archives//html/Amps/2004-01/msg00274.html (8,408 bytes)
- 325. Re: [Amps] info on al-1200 amp (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sun, 25 Jan 2004 07:32:26 -0800
- ** Did you inspect the output bandswitch contacts? _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
- /archives//html/Amps/2004-01/msg00275.html (7,665 bytes)
- 326. Re: [Amps] Alpha 78 B- Resistor (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Sun, 25 Jan 2004 07:32:26 -0800
- ** AGREED ** I would try putting the over-current sampler R in series with the glitch resistor - and then protect the sampler R with paralleled 200A-peak 1n5400-series Si diodes. ** possibly two. di
- /archives//html/Amps/2004-01/msg00276.html (12,524 bytes)
- 327. Re: [Amps] 18 ga. enamel wire (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Mon, 26 Jan 2004 02:28:52 -0800
- ** Electric motor rewinding shops carry 180ºC-rated silicone-varnish/ Cu wire - which is sold by weight on your spool. Bring your own winder. An electric-drill with a chucked-up rod for the spin
- /archives//html/Amps/2004-01/msg00288.html (7,843 bytes)
- 328. Re: [Amps] matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Mon, 26 Jan 2004 03:13:21 -0800
- ** G-G operation for the 4cx350 is seemingly risky due to the delicacy of the grids. The 4cx350 was designed for AB1, grid-driven service. If I were building such an amplifier, I would terminate the
- /archives//html/Amps/2004-01/msg00289.html (8,029 bytes)
- 329. Re: [Amps] ALPHA77 Relay (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Mon, 26 Jan 2004 03:13:38 -0800
- ** The Matsushita/Panasonic type-RSD SPDT RF reed-relay is quicker (1-mS make/break) , quieter, smaller, and not as costly as a vacuum relay. We carry these for retrofitting older amplifiers with hi
- /archives//html/Amps/2004-01/msg00290.html (8,040 bytes)
- 330. Re: [Amps] Horizontal or verticle? (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Mon, 26 Jan 2004 03:13:38 -0800
- ** I would go with base down. I have seen many 8877s/3cx800A7s-et cetera with gold-sputtering 'pollution' that were still usuable if the gold meltballs could be safely parked in the base. __________
- /archives//html/Amps/2004-01/msg00291.html (8,402 bytes)
- 331. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Mon, 26 Jan 2004 07:34:03 -0800
- ** In a grounded-grids, tetrode amplifier, c. 75% of the total grid current flows in the control grid and c. 25% of the current flows in the screen grid. The max control-grid-current rating for the 4
- /archives//html/Amps/2004-01/msg00300.html (7,524 bytes)
- 332. Re: [Amps] Horizontal or verticle? (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Tue, 27 Jan 2004 19:27:55 -0800
- ** UPS second day isn't too bad. Large outer boxes with bags of plastic packing peanuts are helpful. Anything shipped UPS ground should be able to withstand several 10-meter falls onto concrete. UPS
- /archives//html/Amps/2004-01/msg00315.html (10,407 bytes)
- 333. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Tue, 27 Jan 2004 19:27:56 -0800
- ** which means? ** True, but g1-g2 amplification is typically 4 to 5. ** Especially above 1GHz. ** The 2mA max grid current rating would seem to preclude grounded grid operation. ___________________
- /archives//html/Amps/2004-01/msg00316.html (8,756 bytes)
- 334. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Wed, 28 Jan 2004 09:12:55 -0800
- design. ** The thing that makes tetrode RF grounded-grid different from tetrode grid-driven is that in grid-driven, the RF driving signal exists between the RF-grounded screen and the control grid.
- /archives//html/Amps/2004-01/msg00324.html (9,780 bytes)
- 335. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Thu, 29 Jan 2004 02:09:34 -0800
- ** Ian -- How does one convert this figure into a determination of how grid current divides between the grid and the screen during g-g operation? _______________________________________________ Amps
- /archives//html/Amps/2004-01/msg00335.html (9,148 bytes)
- 336. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Thu, 29 Jan 2004 02:27:35 -0800
- ** Good point, George. Not only would the conversion be extensive, the 2mA limit on control-grid current would seem to suggest that a 4cx350 could not be driven to 100% of it's emissive capability i
- /archives//html/Amps/2004-01/msg00336.html (9,306 bytes)
- 337. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Thu, 29 Jan 2004 03:28:12 -0800
- ** When no drive potential exists between the screen and the grid, the tetrode acts as a triode. This is why applying DC screen potential to a g-g tetrode does not increase amplification or reduce t
- /archives//html/Amps/2004-01/msg00337.html (8,548 bytes)
- 338. Re: [Amps] A Crying Shame (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Fri, 30 Jan 2004 03:23:52 -0800
- -- Plastic peanuts in half-full, taped-shut plastic grocery bags work fairly well. [the bags keep the peanuts from shifting around the amplifier during transient]. . ** ... ... ... and tubes that do
- /archives//html/Amps/2004-01/msg00356.html (8,223 bytes)
- 339. Re: [Amps] Drake L7 in need of TLC? Advice please! (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Fri, 30 Jan 2004 03:31:44 -0800
- ** 'Equalizing resistors' tend to unequalize the reverse currents in seriesed diodes. Mfgs of HV Si diode rectifier stacks caught on to this about 25 years ago, [subject discussed in recent ARRL Han
- /archives//html/Amps/2004-01/msg00357.html (8,556 bytes)
- 340. Re: [Amps] Re: matching network (score: 1)
- Author: R.Measures <r@somis.org>
- Date: Fri, 30 Jan 2004 03:38:08 -0800
- ** So if a tetrode with a g-/g2 amplification of 4 to 5 has c. 25% of total grid current flowing in the screen, a tube with a g/g2 amplification of 13 might have c. 8% of the total grid-current flow
- /archives//html/Amps/2004-01/msg00358.html (9,115 bytes)
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