Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 2 Jul 2006 11:53:42 +0200 (CEST)
It must be remembered that the rules (and supply arrangements) are different between countries, and the UK requirements when you take PME (Protective Multiple Earthing) into account can give problems
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 2 Jul 2006 12:02:18 +0200 (CEST)
In Class C, they're rated at 900 watts input. The filament structure is the same as the 3-500, so I'd expect similar performance, just less plate dissipation. For speech without a processor, you'd pr
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 10:06:29 +0200 (CEST)
Wynand - and this applies generally, I think - more than 400W so the last think we need is the regulator having to enforce the regulations< We need to bear in mind the spurious emission requirements
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 10:31:13 +0200 (CEST)
the load and for maximum efficiency all at the same time < This gets perilously close to igniting that argument about whether or not you provide a conjugate match to the tube. Since most linear amps
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 15:37:19 +0200 (CEST)
bandwidth limit. If you are below such a signal level at 3kHz on SSB, you can be doing anything you want in that 3kHz.< You need a bit more of a spectral mask than just a bandwidth limit to ensure th
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 16:53:52 +0200 (CEST)
I missed the message from Jim saying: The neutral is earthed by the electricity supply company on their pole. From that pole, live and neutral are treated as being 'live ' conductors, and are not ear
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 4 Jul 2006 09:38:13 +0200 (CEST)
noise test at various pulse repetition rates. < How about two very closely spaced tones - 10 or 20Hz apart? That should really exercise the ALC circuits - and the PSU effective output impedance. 73 P
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 4 Jul 2006 12:55:49 +0200 (CEST)
I believe that the magic phrase from Bell Telephone Labs was "Jack took father's shoe bench out" 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@contesting.com h
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 5 Jul 2006 13:44:11 +0200 (CEST)
This is an interesting one. Is it assumed that you can't get a fault such that the full fault current flows down the ground (i.e. the protection) wire? Such fault current being greater than the norma
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 5 Jul 2006 15:21:51 +0200 (CEST)
Were there ever any? I can't say I've ever heard of the existence of socket for these, although that doesn't mean much. As far as I know, everyone makes their own from finger stock and/or tubing and
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 5 Jul 2006 16:53:45 +0200 (CEST)
Only if the two loads have identical power factors. If one is capacitive and one is inductive, the currents in the neutral won't cancel. OK. We have to consider the possible fault current during the
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 6 Jul 2006 15:37:21 +0200 (CEST)
at other frequencies, and at the upper end of hf Zi looks like a half decent short circuit. Maybe matching at the top end and then frequency tailoring an input attenuator will work.< I make the input
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sat, 8 Jul 2006 15:16:43 +0200 (CEST)
Exceeding the plate dissipation is another matter altogether, and is I suspect, done at the expense of tube life if not linearity. It is amazing what you can get away with tubes though: remember the
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 9 Jul 2006 08:00:42 +0200 (CEST)
I think the real problem at the end of the day was that the tube manufacturer wasn't going to provide any 'design maximum ratings' for sweep tubes except in horizontal sweep service. Realistic design
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 9 Jul 2006 08:09:06 +0200 (CEST)
Quite likely. But bear in mind what data sheets mean. 'Typical' = 'we measured one' . 'Max' or 'min' = 'we think we'll get a good yield with these numbers' 'Measured in test fixture' = 'this is the o
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 11 Jul 2006 09:39:22 +0200 (CEST)
derated above 5MHz.< What goes wrong with mica above 5MHz? it got used a lot in receiving and transmitting tubes, and as insulation in cavities at VHF and up where quite large RF currents were flowin
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 11 Jul 2006 09:41:56 +0200 (CEST)
What sort of metal can? If it's like a small relay can, the probability is that it's a passive diode mixer - especially if the LO drive is around 500mV rms. If it's a round IC or transistor can, that
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 11 Jul 2006 10:23:03 +0200 (CEST)
You may remember a couple of weeks ago, I asked for comments on the amplifier that was OK at 3.5MHz and went mad at 3.7MHz. At last, I'm at home for long enough to actually look at it. Someone sugges
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 11 Jul 2006 13:48:29 +0200 (CEST)
determine anything by itself. If it did, we'd never be able to build a R/C oscillator circuit now would we?< But we have a case here where the Q of the whole grid circuit is much less than 1, i.e. it
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 11 Jul 2006 14:44:05 +0200 (CEST)
the problem frequency show?< I don't know, of course. And as the thing is now in the process of change, I'll never know what it was. Once the change process is complete, I will measure the reverse is