[1000mp] ARB-704 and Yaesu Mark V

[Pete Smith]

The real problem, with some amps at least, is surges.  For example, my SB-220 had no clamping diode across the T/R relay, which made it virtually guaranteed to weld a small reed relay's contacts closed.  The "fix", from the 1970s sometime, was to add a 220-ohm series resistor as a current limiter, but a FET buffer is a better idea.

73, Pete N4ZR

At 11:26 PM 11/28/2006, Scott Manthe wrote:
>Try using a switching circuit that draws 1 amp with the Mark V's relay and see how long it lasts. I doubt you'd get through a couple dozen QSOs.
>
>The manual can say what it wants, and it's even possible that the relay could handle 500mA at 100V or  even 1 amp at 30 volts, but in either case, it probably won't do it very long.
>
>Replacing those relays isn't fun and the cost of a buffer is cheap insurance, unless of course it's more important to you to be right than safe.
>
>73,
>Scott, N9AA
>
>Art Searle W2NRA wrote:
>>Hi,
>>
>>According to the MrkV Field manual for non-QSK switching: 
>>MrkV Field manual page 14: With the relay now enabled, the MARK-V FT-1000MP
>>Field can support non-QSK linear T/R switching voltages up to 100 VAC @ 500
>>mA, or DC voltage up to 60 V @ 200 mA, or closed-circuit current up to 1 A
>>with DC voltage up to 30 V.
>>
>>and in my Ameritron AL-800 manual:
>>
>>AL-800 manual page 5: Relay:
>>Requires contact closure or sink of +12 Vdc at 100 mA. Back pulse protected.
>>
>>This seems well with specs, right?
>>
>>73 Art W2NRA
>> 
>>
>>-----Original Message-----
>>From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
>>On Behalf Of Pete Smith
>>Sent: Tuesday, November 28, 2006 01:37 PM
>>To: All about Yaesu 1000mp
>>Subject: Re: [1000mp] ARB-704 and Yaesu Mark V
>>
>>Well, you could always RTFM, but why spoil your fun?  The info on this is on
>>page 12 of the Mk5 manual, but the short answer is that you can indeed
>>damage the radio - though perhaps not with the AL-80B.  
>>
>>73, Pete N4ZR
>>
>>At 12:41 PM 11/28/2006, you wrote:
>>  
>>>Why you need the ARB-704
>>>
>>>
>>>
>>>Amplifiers can damage radios if the amplifier has too much relay control
>>>voltage, voltage spikes, or excessive current on the relay control line.
>>>Such damage often appears as "stuck" or "sticky" transmit relays in
>>>    
>>exciters
>>  
>>>or shorted transistors on transmit control lines. In most cases where the
>>>radio is damaged, the system transmits normally but the external amplifier
>>>stays locked in a "transmit" mode. This prevents receive signals from
>>>    
>>coming
>>  
>>>through the amplifier with normal levels whenever the amplifier is in the
>>>"ON" or "OPERATE" position.
>>>
>>>
>>>
>>>Above is the reason I have placed the ARB-704 between my Yaesu Mark V and
>>>    
>>my
>>  
>>>AL-80B.  However I was told that the Yaesu Mark V will not allow this type
>>>of damage to occur and my having the buffer between the rig and the amp is
>>>overkill.  What is the real true?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>  
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