I see a very significant difference between the "approximate" formula and the one mentioned by Jerry; the former predicts that you can't achieve Zo lower than 87 Ohms, whilst the latter demonstrates
Jerry, With respect, the "industry standard" Isotropic reference definition *doesn't* change in the presence of ground - it remains at a power density of Pt/(4*Pi*r^2) in all cases. It may be that le
It's tough to find a way to express a tuner's capability in some succinct and meaningful way. This was my attempt: http://www.karinya.net/g3txq/temp/aat_chart.png Each "cell" represents a particular
Dave, Thank you for the clarification, and for confirming my points: * dBi is always referenced to an isotropic radiator *in free space* * EZNEC is consistent with the industry definition and is not
Power handling really isn't an issue in this application. Connected to a multiband doublet, the SWR wont get much higher than 10:1 on 300 Ohm or 400 Ohm cable. That would put the maximum localised cu
Reading many articles about the advantages of window line you could be forgiven for thinking it is virtually loss-less in most applications; that isn't necessarily the case. For example, when used in
Paul, When you say "bandwidth" I presume you mean "VSWR bandwidth". The Resistive component of the feedpoint impedance of a dipole varies relatively slowly with frequency either side of resonance, bu
I need to replace a fault "Notch" potentiometer on my CorsairII. It's dual-gang, and mounts to the IF/AF PCB as well as to the front panel. I can't see anywhere on the schematic that tells me its Ohm
Neil, For some reason I'm not receiving list postings via my email - only just found your response on the web archive for the list. This is a "spare" Corsair I bought very cheaply a year or so ago. I
The potentiometer wasn't marked other than with a manufacturer's number. It measured 211k across the ends, and mid-way on the rotor the resistance from the slider to either side was 176k/35k, so I th
Jerry, Thankfully, none of that is necessary. It's a stock item: http://www.maplin.co.uk/standard-dual-gang-potentiometers-2207 Steve G3TXQ _______________________________________________ TenTec mail
Jerry, I don't know why it would be different here in the UK, but 220k seems to be a much more common value than 250k. Here's a typical distributor: http://www.electronelec.co.uk/acatalog/Electron_El
Jerry, Now you mention it ......... My recollection of the sequence of events was that the Notch pot was a bit "scratchy" but operated over its full travel. Whilst I had everything apart for the DDS
Folks, The Maplin potentiometer arrived yesterday afternoon and I got a chance to fit it in the evening. It's not the "drop-in" replacement I hoped for, basically because it's slightly smaller than t
Jerry, Yes - it was disappointing. I can't think of any simple way of "fudging it". The Corsair filter circuit has them configured as variable resistors rather than potentiometers, so the usual trick
Charles, Thanks for the suggestions. I see a couple of problems: * The pot mounts directly to the PCB, so swapping the ends means cutting tracks which I'd prefer not to do at this stage. Of course if
Charles, I needed to extend by about 2mm, so I inserted short terminal pins into the PCB and soldered the pot directly to them. It's as if the pot pins were 2mm longer - not enough to do any swap ove
I swapped the potentiometer this morning for the Maplin 220k linear version. It only took 20 minutes second time around, including shortening the new spindle and filing down the bushing. It "feels" s
Jerry, I did get a quote from Omeg. Their part with the closest match would have been 220k with a reverse log taper, the correct size spindle bush, a genuine 1/4" spindle (not 6mm) and the correct le
Jerry, The other thing I need to look out for is a slipped disc in my back! I'd forgotten just how heavy these old radios are. I had to enlist the help of my XYL just to slide it out of its cabinet!