HW-101 for PSK31?

[Kenneth G. Gordon]

On 2 Sep 2007 at 6:58, Paul Blumhardt wrote:

> In regards to using the other gear on the newer digital modes, the
> area that is of most concern is T/R cycle time.

Yes. However, supposedly if your setup makes at least 20 
mS or less, that is amply adequate.

> The old relays take
> too long to go from Receive to Transmit and vise-versa.

Not necessarily. It depends on how they are set up. My HW-
101/SB-200 combo JUST makes 20 mS, but I have "hot-
rodded" the relays in the HW-101 just a bit by changing the 
value of one resistor to 1K from 10K. I'll have to dig out the 
info.

For the HW/SB-101 series, you also have to reduce the 
AGC delay, but this is easily done.

The receiver recovers very fast, usually in under 5 mS.

The method used in research facilities to "hot-rod" a relay is 
really rather simple: use a pretty high voltage to the relay, 
with a dropping resistor in series so that after the relay 
starts drawing current, that current will not be above the 
rated current, and thus the rated voltage will not be above 
the rated voltage.

Say, use 150 VDC and the necessary resistance to drop the 
voltage to 12 VDC when the relay is drawing steady current.

The initial burst of higher voltage causes the relay to pull in 
very quickly.

In one case with which I am familiar for a research device in 
our Chemistry department, a solenoid rated at 2.25 VDC 
was connected to a 400 VDC source. Although I don't now 
remember the exact figures on opening-time, it was in the 
microsecond range. Normal opening time with 2.25 VDC on 
it was in the 100 mS range.

Ken Gordon W7EKB

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