If I remember correctly, you have to remove both covers. You need to access the screws that hold it in from the top and take it out from the bottom. I suggest cutting the wires going to it first and
Grid current with no drive isn't normal. It isn't a question of bias. Try just shorting the amp key line without the transceiver connected. If you get some grid current, either the amplifier is unsta
73 Jim W7RY I noticed today on my TenTec Titan 425 that the grid idle current is around 7 or 8mA on the Ig meter. I see this on the amp when I key my TS930S in ssb with no drive. (modulation). I don'
It is not so easy to make a solid-state amplifier that is stable and has consistent gain from 1.8-30 mHz. One-band VHF (or BC band) amplifiers are simpler. Darn....that seems to be an excellent devic
It's hard to wind a good choke for 160-10 meters, including WARC. If you can copy the Ameritron choke, it seems to be a good design. I don't know the size of the strap you need, but K4MSG (Max Gain S
Is it worthwhile to use a soft-start circuit for the heater of an indirectly heated cathode tube like the 4CX1000A? -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ _________________________________
What are the dimensions? I have a lot of them. On 10/14/2012 2:51 PM, George wrote: I need to replace a standoff ceramic insulator and since they seems to be a thing of the past I was looking for sui
71% overall efficiency is remarkable for a class AB1 amplifier. ACOM1000 and ACOM2000A are without doubt the most popular amplifiers based on GU74B. Many thousands of them are working under the follo
Why do you say that a swamped grid-driven tetrode needs neutralization? I haven't seen this in published designs. Isn't a 50-200 ohm swamping resistor enough to stabilize the amplifier? Agreed on the
I presume you mean the modified B&W 852! That's what I'm planning to use for my 4CX1000A amplifier. I simply lifted the strap from the cold end of the coil so I can insert a 160m coil. The one thing
The one I plan to use is marked '852' and is the low-impedance version with the whole coil made of 5/16" tubing. It has the external 10m strap coil. There is also an 850A (I have one in poor conditio
I'm thinking about this issue now for my project 4CX1000A amplifier. The problem I see is the first element getting chopped by the screen relay pull-in time, which would have to be under 8 ms. to wor
New caps from Ameritron would cost a bit over $100. Diodes are cheap and bleeder resistors available from Mouser reasonably. I can't imagine where the $800 figure came from. Find someone else to fix
The 270 uf ameritron caps mentioned by me and others are $13 each and have screw terminals. They are rated 85 deg. C so if you want 105 deg caps you might pay more. But the snap in types are availabl
I'm using an attenuator like that in my grid-driven 813 amp. It provides a reasonable drive level as well as improving the SWR seen by the exciter. It's important to heat-sink them well because they
I can't suggest a different relay, but I think you should check that there is enough time between the key out circuit closing from your transceiver and the start of RF, as well as making sure that th
Keep in mind that you should arrange some form of coupling as mentioned below and do NOT connect scope probes directly to your feedline. Even 100 watts of RF at 28 mHz on a 50 ohm line will produce a
A friend of mine, now dead, who worked for the Israel Broadcasting Authority told me that he once put one of their transmitters on 40 meters at 10 kW. The antenna was one used for SWBC and aimed at t
I have a power supply that needs to work here in the US and in Israel, where power is supplied as one phase of 240V plus a safety ground. I am not sure if one of the 240V lines is grounded as well. T
Interesting. When I lived there the pins were flat with two of them angled. Apparently the standard changed to round pins some years ago; new sockets accept both types. But what I am interested in is