[Elecraft] Re: K2/100 High Refl shutdown driving amp

Tue Oct 28 14:09:00 2003

There's no info in the AL-800H manual regarding the relay.  It appears to me
to be the exact same relay as used in the AL-80B however.  While thinking
about the timing this morning, it occurred to me that I have another element
adding delay in this case.  Since I use separate antennas for receiving on
160 and 80, and my other transceiver provides no protection for the receiver
front-end in this case, I use a KD9SV unit which disconnects the receive
antenna and grounds the receiver antenna input before grounding the
amplifier relay line.  It uses a small fast relay so there isn't much added
delay, but there is some.   That may be enough to cause me the problem where
other folks won't see it with the same amplifier.  I assume it would be
advisable to continue to use this type of protection when using the K2 with
a separate receive antenna.

I NEVER have the problem on the first key closure of a transmission - it's
only when the relay drops in the middle of a transmission.  I wonder just
what the firmware change would be doing.  Would it delay acting on the high
reflected power situation just a bit, or provide a better way to reset the
K2?

I've used this same configuration with three different solid state rigs
(Icom, Yaesu, Kenwood) and have never seen any problem with them.  It's very
likely that those rigs just don't have quick-acting protection in a high SWR
situation.  At any rate, I'll try whatever you come up with.

73, Floyd - K8AC
----- Original Message ----- 
From: "Wayne Burdick" <[email protected]>
To: <[email protected]>
Cc: "Elecraft" <[email protected]>
Sent: Tuesday, October 28, 2003 12:29 PM
Subject: [Elecraft] Re: K2/100 High Refl shutdown driving amp

> Hi Floyd,
>
> We can correct this in the KPA100's MCU firmware. I'll revise the firmware
and
> send it to you within the next day or two for testing. We may make other
> changes, eventually, but I'd like to quickly eliminate this issue for
those
> using amps with slow relays.
>
> Do you have a spec for how long your amp's relays take to fully activate?
(I.e.,
> the time from the K2's 8R signal going low to the time when the amp is
> presenting a stable SWR to the KPA100.)
>
> 73,
> Wayne
> N6KR
>
>
> Floyd Sense, K8AC wrote:
>
> > Over 6-8 hours of
> > operation, I've had one situation occur three times now.  If I pause
just a
> > bit too long between characters on CW, the amplifier relay drops out and
the
> > problem occurs when the next character is sent.  The problem is a High
> > Reflected power message, and complete loss of output power from the K2.
I
> > suspect that the problem originates when the K2 output rises during the
> > amplifier relay drop and reactivation, presenting the K2 with a
momentary
> > high SWR situation.
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