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Hello All, This isn't exactly Drake stuff, but similar. My Signal/One has developed an AC buzz on transmit. Probably a dead electrolytic. And probably HV, because there is no buzz on receive. The

Don't even think about it until you have a completely working rig. In my experience the only caps that need to be replaced are C2108 on the PS board and (maybe) C9026 on the DR7 board. C2108 should be

Could not have said it better myself.

Thank you everyone for your help. Tr7 has the BW switches out. Have ordered the transistors for the 10R 10T switch on the TX audio board. Just in case. I am going to change all the electrolytic caps

I've heard that 7200 is a good spot to tune up. "Evan via groups.io" <k9sqg@...> wrote: -- 73 -Jim NU0C

Jim I'm getting 11.24 volts with just the +10 volt line and the ground connected. I connected my spectrum analyzer to the PTO RF output wire and get a nice healthy 4.9- 5.5 Mhz signal out and it

I find that tuning up on 40M at night, on top of one of the few remaining SW stations, with an antenna tuner to get the SWR down to 1:1, ?makes a great substitute "dummy load" for certain tests.

Correct. You will see a little more than 10V on the wire due to the voltage drop across the 100 Ohm resistor inside the PTO. The 11V that you saw in the other radio seems reasonable. "Mark N2DMI via

I suspect the DL300 is more robust than a typical MFJ load. :) If you look at the deratng curve it is specified for 30 seconds maximum at 300W and 75W continuous. "Richard Knoppow via groups.io"

Jim if I follow correctly then the PTO MUST be connected to the circuit in order to see the +10 volts on the +10 volt line of the PTO. The zener in the circuit will make sure that the PTO is getting

I recommend the Heathkit Cantenna. Commonly found at hamfests. They're a little messy, and I put mine in a sealed bucket with a coax pigtail coming out the top. Also, I disposed of the original oil,

I've never had a dummy load that was exactly 50 Ohms. It will also change with temperature. An interesting test would be to measure it after it has been heated up. It is also sometimes difficult to

I am not familiar with this particular dummy loD but found others I have which are nominally 50 ohms go up to about 57 ohms when overloaded. I think the resistor us decided into sections which are in

The +150 is connected to the collector of Q4 via the 12K resistor. Q4 is the switch that turns the PTO off when transmit control comes from the receiver, by shorting the +150 to ground through the

I have a DL-300 I've been using for testing my TR-4 and MN-2000. I decided to measure it's DC resistance and found it is 56 ohms. I expected either 50 or 52 ohms so was a bit surprised. I tried

Let me see if I follow. +150 (regulated) goes through R140 to base of Q4. +10 or +11 volts from base of Q4? I guess? The PTO is out of the rig entirely. I measured +44.5 volts where the +10 volts wire

Do you get 10R anywhere on the main board? Look for bad solder joints everywhere that the 10R is connected, starting at the 10R pin on the filter board? The traces are very easy to follow on the main

Don't panic. :) I have limited experience with the 4-line transceivers but looking at the schematic in a TR4-CW manual I see that the VFO is fed off the +150V regulated through a 12K resistor. Inside

I just measured the other TR-4CW (without RIT) at the sane points BUT the PTO is stll connected and I measure +11 volts. I can live with 1 volt higher but not +44 volts. I can see if I broke something