Brian,
I fully agree that external sequencer could solve some of the issues
discussed. Still I have couple of notes.
1)Sequencers are not designed to work with automatic ATUs because the amount
of time required for ATU to reach tuned status is not known forehead.
Therefore PTT signal to PA should be generated by ATU because only ATU
"knows" when tuned status is achieved.
2) Since there is "PTT for PA" connector is already build into ATU, why not
allow user to set programmable delay thus excluding the necessity for a
separate sequencer? When I go on expedition every extra box (with associated
cables and connectors) is counted.
73, Igor UA9CDC
----- Original Message -----
From: "Brian Alsop" <als...@nc.rr.com>
To: <elecraft@mailman.qth.net>
Sent: Sunday, December 09, 2012 9:12 PM
Subject: Re: [Elecraft] [KAT500] Help with KeyLine Interrupt on
KPA500(Video)
This whole issue has been solved by VHF/UHF stations a long time ago. They
use a sequencer to key and unkey various components with appropriate
delays to prevent damage.
They can be built or bought fairly cheaply.
Yes it would be desirable to have the "sequencing" be automatic. One
"size" is unlikely to fit all though.
73 de Brian/K3KO
On 12/9/2012 15:02, Igor Sokolov wrote:
IMHO adapting amplifier to work with KAT500 is not the right way of
doing it because KAT500 is supposed to work with many different amps of
600 watt class.
Yes, PTT is generated by the radio and then passed to KAT500. KAT500
should generate it's own PTT signal for PA based on it's own KAT500
status and incoming PTT signal from the radio. If incoming PTT is
present and antenna is matched then KAT500 generates PTT for the amp.
This will create additional delay equal to switching time of KAT500
relays (minimum) plus some time required to analyze frequency and bring
KAT500 to matching state. That is the price to pay for use of the
automatic tuner.
This will exclude PA faults and relays hot switching in KAT500.
But then this feature can be user selectable. If you do not need it just
do not use it.
The question remains, is it possible to do it all in the firmware or
hardware mods will be required.
73, Igor UA9CDC
----- Original Message ----- From: "ke9uw" <c-haw...@illinois.edu>
To: <elecraft@mailman.qth.net>
Sent: Saturday, December 08, 2012 6:18 PM
Subject: Re: [Elecraft] [KAT500] Help with KeyLine Interrupt on
KPA500(Video)
The PTT is generated by the transceiver. The KAT500 passes it thru to
the amp
unless the KAT is tuning a high SWR. The problem is that the amp goes
into
fault before the KAT can OPEN the key line. Firmware in the KAT with
some
delay is not the answer...it's already too slow for the amp. If there
is any
programmable delay in the KAT, then a firmware change might be to
speed that
up if possible. But I doubt that it is possible since it's a relay
opening
in the KAT which requires some milliseconds.
I'm guessing the only Elecraft solution is to delay the amp's response
to
the high SWR so it doesn't "Fault" giving the KAT time to open the key
line.
So the change in firmware we are waiting on is for the KPA amp.
Help me if I'm missing something here.
-----
Chuck, KE9UW
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