Would it help to connect the two outputs in parallel, to get the fastest possible turn-on from HSEND, and then a slightly delayed release from the relay? HSEND -> [transistor switch] -> [ACC output i
There is much less 2m SSB activity than there used to be, but the G4AJW screen stabilizer is still "dear to my heart" as the ancestor of the solid-state circuit that I use. As far as I know, G4AJW in
seial a resistor to replace it, when the negative screen current control the total resistance so the screen voltage still it a good idea? It works for me... and about 800 others, so far (shameless pl
Thanks for posting the correction, Carl. It has been several years since we parted company with Down East Microwave, in a very friendly way when DEMI decided to concentrate on their core microwave bu
Don't worry, your English is fine, but sometimes we all need to use more words :-) A shunt regulator is probably the best solution for tetrodes up to the 4CX1000-1500W class, but for larger tube like
Many thanks to Carel and Hsu (and Racal) for some interesting ideas! I will be out of town for two days now, so will comment later. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________
I'm glad the Pi-net calculator worked for you. As for the &%¥#?@ transformer, have tried checking it out with M0KGK's 'PSU Designer' software? Follow the link (below) and you can also download some H
Good regulation requires two things: low transformer winding resistances *and* sufficient capacitance. If the winding resistances are much too high (which seems to be the case with Steve's transforme
I am arranging a SK sale of various QRO parts. A buyer who had called to collect an amplifier has noticed some 4CX5000A tubes and an SK-300 socket. Please can anyone suggest fair prices for the tubes
Thanks very much to everyone for responding so quickly, both on-list and off. Deal done and all parties satisfied. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek _______________________________
American surplus too! But it's only to be expected, because far fewer sockets have ever been manufactured compared with the numbers of tubes. A commercial amplifier may use several replacement tubes
The more independent bleeder paths you have, the better - so if one resistor chain fails, you still have at least one backup to discharge the capacitors. For that reason I would always build a separa
But after that initial surge, the truly dedicated obsessive must move on to worry about the stability of the filament voltage. So now our filament supply includes a hot, temperature-variable thermist
But also a different anode cooler with a genuinely higher dissipation. That's right. The 1500B would produce as much output as the 1000A if Eimac had chosen to specify different operating conditions.
By all means read Eimac's 'Care & Feeding' for the tube manufacturer's viewpoint. But by far the best books on the wider subject of transmitter design are the ones written by the Collins engineers: '
Sorry, Peter was right. It is essentially the same air cooler on both tubes, but with an increased air flow rating for 1500W. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ____________________
Like the tiles on the outside? -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/m
Same here. I suspect those voltage ratings are for square-cut open ends. More important is that the connectors include their own chassis ground connection, and the coaxial cables will very probably s
I completely agree. The most dangerous situations are often when the amplifier and HV supply are powered up with temporary connections for fault-finding. In that case, there may not be as many redund
RX overload and purity of 2-tone sources are only important if the TX IMD is good (ie low). But there are no such problems when measuring BAD signals. These only require a dynamic range of 30-40dB, a