HW-101 for PSK31?

[Kenneth G. Gordon]

On 1 Sep 2007 at 15:16, Fred Wittman wrote:

> Has anyone succeeded in using an HW-101 for modern digital modes,
> namely PSK31?

I plan to use mine for just that sort of service.

>  Seems to me it has two things in its favor, namely
> finals that are inexpensive and easy to replace if overstressed by
> digital,

You can very easily cut back the power output to just about any level 
simply by adjusting the CW/MIC GAIN control.

> and a cw filter that can be engaged in all modes.  Now
> whether the VFO is stable enough for the job I don't know.

The VFO is stable enough. However, the dual-Jackson Brothers drive 
sometimes makes the VFO LOOK unstable because when the drives 
get old, they get "bumps" in the grease. I have a DD-103 digital dial 
on mine and once I get between the bumps, or on top of one, the VFO 
stays within 10 Hz or so once it is well warmed up.

However, the method that Heathkit used to voltage-regulate the FET 
VFO's voltage is "iffy" to me, at best. I plan to change mine to be 
more stiff, and so that it doesn't rely on the stability of the buffer's 
cathode current.

Once I have done that, I can report back here after testing.

The relays DO switch fast enough for digital modes, but you have to 
set the VOX delay to zero, adjust the anti-trip to zero, adjust the VOX 
sensitivity to zero, and then use a switch in parallel with the mic 
switch. My PK-232-MBX  then switches both the HW-101 AND the 
SB-200 fast enough for Amtor.

There is a really simple mod which adjusts the value of one resistor 
such that it "hot rods" the relays a bit, making for faster and more 
certain switching.

After changing that resistor, the first "dit" is no longer cut off when 
keying CW at 40 WPM.

Ken Gordon W7EKB

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