[1000mp] ft1000mp mkV amp switching

Thu, 29 Aug 2002 18:13:46 -0700

Hi Pete. Do you use DX4WIN? We are trying to figure out to to get it up and
running, with limited success.

Hope you all are well.

Jim

-----Original Message-----
From: Pete Smith [mailto:[email protected]]
Sent: Thursday, August 29, 2002 6:04 PM
To: [email protected]
Subject: Re: [1000mp] ft1000mp mkV amp switching

At 02:28 PM 8/28/02 +0200, you wrote:
>Any explanation of the switching difference ?
>Or any experience  swiching a SB220/SB221 with the mk V ?
>Or any experience  qsk swithing the a modified SB220/SB221 (AG6K design) 
>with the mkV ?

A problem with the SB-220 is that in addition to the voltage and 
steady-state current, there is a current transient on switching that can be 
very hard on relays.  In the past, a series current limiting resistor has 
been used (~220 ohms), but an FET switch might even be a better solution, 
with the transceiver only called upon to switch a few milliamperes at 
relatively low voltage.

My modified SB-220 uses a QSK circuit developed by K9MA, which uses +12V 
delivered to the gate of an FET to initiate the switching sequence.  When I 
got my Mark 5, he kindly provided me a circuit that would supply that 
voltage on relay closure, using another FET and 12 volts stolen from the 
transceiver.

73, Pete N4ZR
Sometimes a tower is just a tower

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