[1000mp] MPV Driving SB220

[Jan Erik Holm]

I see, then I do know what it is.

Well now, the SB-220 has a AC operated relay, need
I say more?

73 Jim SM2EKM
------------------------------------------------------------
Bill Gode, Sr. wrote:
> Snubbing Diode (From Wikipedia):
> 
> When the current flowing is dc, another often seen form of a snubber is 
> a simple rectifier diode placed in a circuit in parallel with an 
> inductive load (such as a relay coil or electric motor). The diode is 
> installed in the direction that ordinarily does not allow it to conduct. 
> When current to the inductive load is rapidly interrupted, a large 
> voltage spike would be produced in the reverse direction (as the 
> inductor attempts to keep current flowing in the circuit). This spike is 
> known as an "inductive kick". Placing the snubber diode in inverse 
> parallel with the inductive load allows the current from the inductor to 
> flow through the diode rather than through the switching element, 
> dissipating the energy stored in the inductive load in the series 
> resistance of the inductor and the (usually much smaller) resistance of 
> the diode (over-voltage protection). One disadvantage of simple 
> rectifier diode used as a snubber is that because the diode allows 
> current to keep flowing, the relay may stay picked-up slightly longer; 
> some circuit designs must account for this delay in the dropping-out of 
> the relay.
> 
> 73,
> 
> Bill, W9NHQ
> 
> 
> ----- Original Message ----- From: "Jan Erik Holm" <sm2ekm at telia.com>
> To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
> Sent: Tuesday, October 24, 2006 8:34 AM
> Subject: Re: [1000mp] MPV Driving SB220
> 
> 
>> What is a snubbing diode? I have never heard that
>> expression before.
>>
>> /Jim SM2EKM
>> ---------------------------
>> Pete Smith wrote:
>>> You can also play safe by putting a 220-ohm resistor in series with 
>>> the switching lead to limit the current through the relay contacts; 
>>> that device was published in QST many years ago, when relays in 
>>> TS-930s like mine were being fried by the relay current - the stock 
>>> SB-220 relay has no snubbing diode, which may be part or all of the 
>>> problem.
>>>
>>> 73, Pete
> 
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