I just aquired a Kenwood TL-922. Before placing it in service I will add some circuit refinements such as step start and other changes as described by others. One item that I cannot find information
? Briefly: The filament transformer is unfused. It has an 11v winding and an 80v winding. If either secondary winding is shorted, the transformer will literally melt down. The 80v winding powers a +
The best thing you can do for the TL-922 is get rid of the series connected filaments by replacing the filament choke and transformer. Even though the series-connected filaments have a "voltage equal
Rich gave good advice, except for the parasitic stuff. He has a fixation and pet theory that almost any failure is do to a "parasitic". Sorta like ethnic cleansing applied to PA's, where those nasty
I recently put a new diode rectifier board for the screen voltage supply in my HF amp. I put it in the 'input' compartment of the amplifier and was a little careless not to put the board in the scree
? A photograph of a grid/filament shorted 3-500Z appears on p. 15 of the September, 1990 *QST*. The title of the article is "Parasitics Revisited". ? The 922 was designed for the TS-820S transciever
Tom ? Why?. My TL-922 produces no audible hum-modulation on SSB. I hear no hum-modulation from other 922s. Henry has been using seriesed filaments for years. ? Perhaps -- if the filaments are not of
Hey, I thought parasitic oscillations were the root of all evil? Wow, it's a good thing we didn't try to recall all those 3CX1200A7 amplifiers that work just fine. Whew! Tnx Tom! 73, Dan Magro W7RF,
Picking up one of Rich's points: Here's part of a message sent to me some months ago, by someone who reads these debates but chooses not to take part publicly - (Quoted with permission, of course. Th
Boy now thats a parasitic I wouldnt mind having, all the parasitics that I have seen , most of them around the 4-1000 amplifiers, cause damage to say the least. When the amp takes off uncontrollably
Rich is a master at misquoting people. I plainly stated that I had trouble getting the tube to oscillate at VHF and couldn't make it oscillate until I removed one or two ground leads from the grid pi
Interesting Peter, HF oscillations and instability will cause arcing, VHF oscillations however is the topic here. VHF oscillations will not arc bandswitches because they are shunted to ground by the
Not true. If you simply close the antenna connection contact before the input connection contact, all internal arcing problems from hot-switching disappear. That simple change makes sure the amplifie
Sounds like you have confused outgassing or gas ingress, a fairly common occurrence, with a parasitic. High vacuum arcs are common in tubes, especially old used glass tubes. I guess if we don't know
? Even so, driving RF will be across the input contacts before they close. This will result in arcing the input contacts during closure. ? If input contact arcing takes place, transients are fed to
? Readers can check Will's archive to see what Mr. Rauch stated during the grate parasitics debate. - to find the place, search for "5 Dec 1996" or "161MHz". This is the part of the debate where Mr.
? To assist in identifying what kind of problem caused an event, measure the resistance of the parasitic suppressor resistor(s). Such resistors are virtually shorted by roughly 0.002 ohms of copper
? As I recall, during the grate parasitics debate, Mr Rauch disclosed that had measured self-resonances in Tune-caps that were in the 100 to 200 MHz range. Rich... R. L. Measures, 805-386-3734, AG6K
More typical nonsense and distortion of fact by omission, or else you don't understand grounded grid PA circuitry. Either way, your advice is incorrect. The input circuit is AFTER the relay and BEFO
The "omission of fact" that you used to distort the answer was that the particular capacitors I measured with high VHF low UHF resonances contained SERIES resonances, where the impedance went through