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References: [ +from:df3kv@t-online.de: 314 ]

Total 314 documents matching your query.

201. Re: [Amps] grounding grids (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Thu, 30 Jul 2009 21:48:43 +0200
The un-bypassed emitter or cathode resistor is still causing NFB, the voltage developed across the resistor is out of phase with the input signal and in phase with the output voltage. That kind of NF
/archives//html/Amps/2009-07/msg00411.html (10,978 bytes)

202. [Amps] FW: parasitic oscillation techniques (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Mon, 24 Aug 2009 14:31:42 +0200
Blown for what reason? Lossy parasitics traps are in use in Germany for more then fifty years. When tubes blow there are other reasons then suppressors, never heard of such case. 73 Peter Measures wa
/archives//html/Amps/2009-08/msg00434.html (8,298 bytes)

203. Re: [Amps] RF parts and parasitics!! (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Wed, 26 Aug 2009 20:41:19 +0200
But the cathode choke still keeps the impedance low 73 Peter If drawing a conclusion from a test you must first have the proper test setup with the proper equipment. Using an SWR bridge to determine
/archives//html/Amps/2009-08/msg00504.html (12,464 bytes)

204. Re: [Amps] RF parts and parasitics!! (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Thu, 27 Aug 2009 18:44:57 +0200
Not in mine, no instrument, no resistor, cathode via the choke and heater transformer c.t. grounded 73 Peter Sure' there is bound to be a swamping resistor of a few ohms for current reading purposes
/archives//html/Amps/2009-08/msg00548.html (9,395 bytes)

205. Re: [Amps] SB-220 bias question (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sat, 29 Aug 2009 18:56:58 +0200
To do so you have to modify the pi-net, as the output impedance of the tube will be much higher 73 Peter My whole point is to run the tubes at higher plate voltage with less plarte and grid current f
/archives//html/Amps/2009-08/msg00603.html (8,188 bytes)

206. Re: [Amps] SB-220 bias question (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sun, 30 Aug 2009 01:21:26 +0200
And the first thing to blow up will be the band switch 73 Peter Absolutely "way" ... if you run the higher late voltage with lower current and only 700 - 800 watts out in RTTY, the plate load impedan
/archives//html/Amps/2009-08/msg00614.html (11,663 bytes)

207. Re: [Amps] SB-220 bias question (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sun, 30 Aug 2009 16:46:50 +0200
Changing the Q at constant power level changes the currents in the pi-net, not the voltages 73 Peter ORIGINAL MESSAGE: REPLY: I think you are mistaken about the circulating currents going up. If that
/archives//html/Amps/2009-08/msg00634.html (9,923 bytes)

208. Re: [Amps] SB-220 bias question (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sun, 30 Aug 2009 21:22:26 +0200
Circulating current is not increasing because drive is reduced, but because Q is increased (L remains the same) by tuning for lower output at higher voltage. 73 Peter ORIGINAL MESSAGE: REPLY: There i
/archives//html/Amps/2009-08/msg00642.html (9,568 bytes)

209. Re: [Amps] Pair of SB-220s (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sun, 6 Sep 2009 20:25:00 +0200
It will work with 1/4 coax transformers, but I would always prefer wide band 2:1 ferrite transformers (as used in stack matches)plus a variable phase shifter in one channel. I did that in the past wi
/archives//html/Amps/2009-09/msg00063.html (8,336 bytes)

210. Re: [Amps] Vacuum variable hipot (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Fri, 18 Sep 2009 20:58:17 +0200
I think that is still normal. The 5KV rating normally is the peak AC test voltage rating at maximum capacity, not the working voltage. When those are stored for a longer time the vacuum might not be
/archives//html/Amps/2009-09/msg00242.html (9,146 bytes)

211. Re: [Amps] Checking Plate Choke resonance (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Mon, 12 Oct 2009 15:04:06 +0200
I have never seen such high impedances at amplifier chokes. Most of the chokes in ham radio amps are not even twice the plate load. The famous Rfparts 225µH transmitting choke is just 2,5k ohms on 16
/archives//html/Amps/2009-10/msg00181.html (7,300 bytes)

212. Re: [Amps] Checking Plate Choke resonance (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Mon, 12 Oct 2009 19:10:27 +0200
Hi Carl, Yes, in the late 50s I still used large choke inductances like 2.5mH to feed the parallel resonance output circuit of my 40/80 transmitters and amplifiers. There at the cold end any choke re
/archives//html/Amps/2009-10/msg00183.html (10,279 bytes)

213. Re: [Amps] Eimac tube on the 'bay (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Tue, 13 Oct 2009 19:46:25 +0200
Hi Alek, The rating plates of our 3-phase transformers do not show the voltage of the coil but the voltage between phases. Current capacity will be the given current of 1.5A times sqrt3 which will be
/archives//html/Amps/2009-10/msg00198.html (20,675 bytes)

214. Re: [Amps] Checking Plate Choke resonance (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Wed, 14 Oct 2009 02:58:56 +0200
The parallel resonant circuit will look like a very large resistor to the RF voltage. Circulating current is AC current times Q, but there is none or very little AC current. 73 Peter The parallel res
/archives//html/Amps/2009-10/msg00204.html (9,363 bytes)

215. Re: [Amps] HELP...2x GS35b (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Fri, 16 Oct 2009 23:58:38 +0200
Hi Jean-Pierre, The output Z for 2 GS-35b will be about 850-900 Ohms at 3KV 2A. You can´t drive the tube to an anode voltage of 0V, so you may only use the voltage swing for your calculation. The mod
/archives//html/Amps/2009-10/msg00237.html (8,327 bytes)

216. Re: [Amps] tank calculations - need input (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Sun, 18 Oct 2009 19:48:30 +0200
I don´t see anything wrong how you set the pi components. All values are the same with my calculations. 1000pf for C2 plus 1500pf total added should load nicely with 5µH on 80m at a Q of 12. What kin
/archives//html/Amps/2009-10/msg00247.html (10,983 bytes)

217. Re: [Amps] tank calculations - need input (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Mon, 19 Oct 2009 03:01:47 +0200
Yes, a Q of 7 is OK at that impedance if harmonics at only -24db are acceptable. Multi-Op stations are more interested in -35 to -40db. With such low Q one should make use of Pi-L. 73 Peter If you wa
/archives//html/Amps/2009-10/msg00250.html (13,177 bytes)

218. Re: [Amps] bifilar tuned input (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Fri, 6 Nov 2009 20:22:20 +0100
I just finished a multi band amp with such circuit which works extremely well. The pair of tubes are similar to 4-1000A and are highmu configured. Gain is very good and reaches almost 14db using 6KV
/archives//html/Amps/2009-11/msg00087.html (8,031 bytes)

219. Re: [Amps] Dummy Loads & Wattmeters (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Thu, 3 Dec 2009 15:51:31 +0100
No, first you have to deduct the reflected power from the forward power and your reading should be as near as possible to full scale for best accuracy. By using a 2500W slug your reading might be far
/archives//html/Amps/2009-12/msg00072.html (7,429 bytes)

220. Re: [Amps] Chinese DIN connectors (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Thu, 10 Dec 2009 22:30:49 +0100
I would never buy a DIN connector with melting isolation while soldering. Probably you bought something like 7/16, but not DIN. All DIN connectors are Teflon isolated. Try Spinner, Telegärtner, Huber
/archives//html/Amps/2009-12/msg00277.html (10,072 bytes)

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