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Re: K4DPK VFO Stabilizer

 

Paul

I have not read the other suggestions, but two come to mind

1. Can you unground one side of the AC for heaters.? Normally it is a twisted pair.? I used a bridge to pull down the heater voltage on a R4C from 7.0 to 6.5. (It had forfeited some tubes for transistors)

2. There are very cheap DC to DC converters (sometimes called regulators or step up or step down (buck) but are adjustable for output voltage) from China on the internet, for $5.? So rectify your heater voltage - half wave may be OK.? The two sides of the converter are electrically isolated.

I used one also on a drake R2C using a replacement mains transformer that did not have a 12.6V output.? So boosted from 6.3V.? If there is interference put the ferrite beads on the wires.

Nigel




On Thu, Jan 18, 2024 at 8:09?PM Jim Shorney <jimNU0C@...> wrote:

Even better, use a 317T regulator *with recommended external caps*. Better specs and you can set the voltage to exactly what you want.

73

-Jim
NU0C

On Thu, 18 Jan 2024 11:52:15 -0800
"jerry-KF6VB" <jerry@...> wrote:

> On 2024-01-18 11:17, Paul Christensen wrote:
> > I'll soon be installing a K4DPK VFO stabilizer in my TR-4Cw.? The
> > stabilizer works on 10-14 VDC.? Since there's no low voltage in the
> > TR-4Cw, I'm curious how others have attempted the supply voltage
> > dilemma,?
>
> *** I had a similar requirement for my KWM-2.? I used a half-wave
> rectifier
> off the filament circuit, feeding a TO-92 three-terminal regulator.?
> Which
> has far better ripple rejection than a zener diode.
>
> Actually, I wound up using two half-wave rectifier circuits;? one for
> a BHI noise reduction module inserted in the audio stream, and the other
> for a DC fan.
>
>? ? In the case of the KWM2, there was an empty tube socket on the
> chassis,
> meant for a noise blanker option.? This had most of the signals I
> needed,
> including a switch closure for the "NB" position on the front panel.? So
> now when I click to "NB", the band noise goes down.? I mostly leave it
> in
> "NB".
>
>? ? ? ? ? ? ? ? ? ?- Jerry, KF6VB
>
>
>
>
>



--

73

-Jim
NU0C
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