HW-101 for PSK31?

[Fred Wittman]

Kenneth G. Gordon wrote:

>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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>  
>
Ken,

What does this do to the life of the relay?  Mine's about 25 years old.

Fred

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