Need DX--40 Expert
Marshall
mmdues at HAL-PC.ORG
Sun May 5 23:02:21 EDT 2002
Hello, Ron,
In late 1959, when I was studying for my novice amateur radio license, I
wrote to Heath Co. for information on a DX-40 transmitter to go with my
AR-3 receiver. They sent me a four page specification packet that had
a picture, specifications, schematic and block diagram description of
the circuit. The schematic has the components you list for your
schematic
#1 scenario. The date on the lower left corner of the package is
8/3/59.
I have had this in a reference file folder since 1959. ( I never did get
the DX-40, instead, I built a transmitter out of a QST article in 1960.)
I hope this is helpful in dating your research.
Best regards,
Marshall Dues - WB5MYO
Katy, Texas
Ron wrote:
>
> I am in the process of doing a restoration on a DX-40 and I have come across
> two variations of the wiring schematic. I wonder which is the most recent
> version. Hope someone on this list can answer this for me.
>
> The differences are as follows:
>
> Schematic #1: 12AX7 Speech Amp plate supply line---has a 0.1mfd cap to
> ground
> Shcematic #2: 12AX7 Speech Amp plate supply line-- has a 20mfd 450V
> electrolytic to ground.
>
> Schematic #1: 6DE7 Modulator Tube--Pin 9 Cathode--10K 5W Resistor in
> parallel with .5mfd cap to pin 2 of function switch.
> Schematic #2: 6DE7 Modulator Tube--Pin 9 Cathode--12K 5W Resistor in
> parallel with 2mfd cap to pin 2 of function switch.
>
> snipped ...
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