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THE AM BULLETIN BOARD => Technical Forum => Topic started by: ko4nrbs on October 07, 2023, 09:35:26 AM



Title: DX-60B Wiring Mistakes
Post by: ko4nrbs on October 07, 2023, 09:35:26 AM
I discovered something odd in my DX-60B. 

1.  Referring to the schematic R6 in mine is 180 ohms while the schematic calls for an 18K ohm resistor. 
2.  In my rig C47(silver mica) capacitor and the 1mh inductor is terminated to pin 9 of V2.   It is shown not connected on the schematic.

Should I correct this, so it reflects what is on the schematic?

(https://i.imgur.com/iDAgqQ5m.jpg)
(https://i.imgur.com/LPrHK74m.jpg)
73,
Bill KO4NR




Title: Re: DX-60B Wiring Mistakes
Post by: KD1SH on October 07, 2023, 10:24:12 AM
  Regarding the R6 resistor, are you sure that the 3rd band on the resistor hasn't just faded from orange to brown? Did you actually measure the value?
On the 6CL6, pins 2 and 9 are both tied to the grid, so the junction of C47 and the 1mh inductor absolutely must be connected to at least one—preferably both—of those pins, otherwise no self-bias on the tube, and no grid drive. My schematic shows it properly connected.


Title: Re: DX-60B Wiring Mistakes
Post by: ko4nrbs on October 07, 2023, 10:47:23 AM
My mistake.  I removed it from the circuit, and it is 19K ohm.  The color code is faded.  I will go ahead and replace it.

My schematic shows a circle with a 2 in it alongside a circle for Pin 9.  The construction manual does instruct you to make the connections.
(https://i.imgur.com/Toc96VQ.png)

73 and thank you,
Bill


Title: Re: DX-60B Wiring Mistakes
Post by: KD1SH on October 07, 2023, 11:05:20 AM
The circle with the 2 and the circle with the 9 just indicate that both of those pins go to the same place within the tube. In theory, the inductor could connect to either. In practice, I would prefer to connect to both, but it probably wouldn't be significant except in VHF/UHF applications. Tube pins that connect to nothing just make me nervous.
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