Hi Mike, all of your voltage readings should be measured from the cathode terminal or as close to the cathode terminal as possible. There are several failure scenarios that would allow those voltage
The swr bridge certainly could be part of the problem. Another often overlooked cause of this problem is where the input and output coax shield/center conductor is split apart to make connections to
2 cent reply de k5gw: You will need a reliable test setup to know when you have reached your design goals. You might consider starting with the test setup and do a thorough evaluation of your FT1000D
Tom, if you are operating AM as in steady carrier, the resistor bias is probably ok. If you plan to operate SSB or cw then the bias voltage will be changing from zero with no drive to a maximum value
Doesn't grounded grid/cathode driven operation provide much if not all of the degeneration/negative feedback we are discussing here? 73, K5GW In a message dated 12/14/2005 11:10:17 P.M. Central Stand
Terminals A-C are clearly the secondary connections. I trick to help sort out the primary connections is to apply 120vac to the secondary and start measuring voltages on the primary connections. Once
If the fuse blows, the cathode voltage can rise to near the plate potential. Most tubes will arc from cathode to filament or grid with this much voltage present. This is not good for the tube! The re
Hi Bill, most of these nice meters begin their life as a much lower value movement; 500 microamperes being a common value. If yours is one of these you can remove the internal shunt and provide your
If this was already covered please excuse my redundancy. The input capacitance of the GS31B is likely on the order of 22pf. Two of them 44pf. These values as well as any strays in the circuit have to
Hi Steve, I have not been there/done that so this is a speculative answer at best: When you increase drive and then load heavier to reduce grid current, the out put C is reduced, not increased. It so
Set your VOM to volts, connect it to the xmt keying jack on the AL80 and measure the voltage to ground (chassis). Then switch the VOM to current and measure that. Compare the numbers with the ratings
Hi Guys, I'm just in the final stages of tuning up a GS35B on 144 MHx. The original design was down by DJ5RE. It is featured on the N2DX QRO Russia Site as a project by DG2KBC. It has all gone togeth
A google search for "origin of rookie" turns up over 700,000 hits. Some plausible explanations appear on the first page returned but there seems to be no one definite answer. It is kind of like the o
Is the required 25 to 50 ohms current limiting resistor installed in series with the B+ to the tube? 73, Gerald K5GW In a message dated 1/26/2006 12:59:49 P.M. Central Standard Time, Xmitters@aol.com
Perhaps you could find a 12.6vac transformer rated for 8 or 10 amps and series boost the 120vac enough to overcome the diode voltage drops. The 10v 100A transformer would need to handle some extra st
Bob, you can purchase one from Mouser Electronics, manufactured by Hammond. They have split primaries and secondaries so you can wire for 120 or 240vac. I would use one with twin 6.3vac windings to a
This schematic is a bit hard to read but it looks like the screens of the tubes are grounded. If this is the case, then the cathode has to be above ground for d.c. by the screen voltage value. RF is
Steve is right on the money here. Many capacitor filters will cause peak currents about 5 times average but the current only flows 1/5 of the cycle. Since heating is related to current squared, the t
I don't have the answer Bill but there is this to consider: In the capacitor filter, current only flows about 20% of the cycle. This is very much not a sine wave and I wonder how rms even applies in