[Heathkit] DX-60B HV DC Output

[hwhall at compuserve.com]

1. The 6146 in class C draws in the neighborhood of 4ma (per datasheets), so R30, R11, R12 (total ~22.4K) can drop almost 89 volts for that current, leaving ~40 volts for the grid. Close enough to  your measured 38 volts, given that we don't know the exact grid current or the ohms tolerance + drift on the resistors.
2. The 6CL6 control grid (pins 2, 9) is biased -115V which is likely nearly to or past cutoff (datasheed wasn't specific), hence very little or no grid current, & hence very little voltage drop through the resistances feeding THAT control grid. But R10 & R30 are also dropping voltage due to V1's grid current. As an approximation, R30+R10+R6 seem to be (per your measurements) dropping about 15volts, so the 6CL6 grid current is less than 0.5mA.
Make sense?
Wayne
WB4OGM

-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com>
To: Wayne Hall <hwhall at compuserve.com>
Cc: heathkit at mailman.qth.net <heathkit at mailman.qth.net>
Sent: Fri, Jul 23, 2021 2:34 pm
Subject: Re: [Heathkit] DX-60B HV DC Output

The -38 is on the 6146 and the specified -115V is on the Driver.
Mark

On Fri, Jul 23, 2021 at 5:12 PM <hwhall at compuserve.com> wrote:

>You can't go from the same source voltage through 22K to the 6146 and have
-38V,  and through 22K and then 18K + 4.7K and have -115 volts.<
You might, if those 6146 connections are to different pins (i.e., different tube elements) because (for example) plate current differs from screen grid current which differs from control grid current which differs from cathode current. Different current drawn through different resistances will result in different voltage drops. I note that your concern  is different pin voltages at different pins - aren't those different elements in the 6146?

WayneWB4OGM

-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com>
To: Heathkit List QTH <heathkit at mailman.qth.net>
Sent: Fri, Jul 23, 2021 11:42 am
Subject: Re: [Heathkit] DX-60B HV DC Output

Making progress.    I have a question on the schematics.

I measure the bias at -130V at the junction of C37/C38.    If you go
through R30 (22K) to Pin 5 of the 6146 the bias voltage is supposed to be
-38V as indicated on the schematics.  We can ignore the parallel
combination of R11 and R12 as R30 is significantly higher.

Now, If I go through the same R30,  then R10 (4700) and R6 (18K) to Pins
2/9 of V2,  the schematics say -115 Volts.

You can't go from the same source voltage through 22K to the 6146 and have
-38V,  and through 22K and then 18K + 4.7K and have -115 volts.

Is the schematics incorrect?

Mark K3MSB
______________________________________________________________
Heathkit mailing list
Home: http://mailman.qth.net/mailman/listinfo/heathkit
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Heathkit at mailman.qth.net

List Administrator: Gary Harmon, K5JWK
** For Assistance: gharmon at idworld.net **


This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html