To: <amps@contesting.com>
>Date: Fri, 15 Nov 2002 16:25:35 +0000
>From: "Ian White, G3SEK" <G3SEK@ifwtech.co.uk>
>Subject: Re: [Amps] SB220 T/R relay substitution
>
>Tony Wanschura wrote:
> >Does anyone know how much delay there is on the IC765 and 746 between
> >PTT signal and RF output?
>
>On the 746 in all modes, it's about 12-14ms between the first
>key-down/PTT and the start of RF output.
On my 765 RF output begins 8.5ms after key/PTT closure (after that the RF
has a risetime of 3.5ms for 100% output on CW). This is the same on QSK, or
VOX, or if the rig is held on tx with the MOX switch.
On QSK, RF output begins to decay within 0.5ms of key up and takes another
3.5ms to reach zero. Hence the CW elements are each clipped by 8ms on QSK.
If the tx is held on, eg with VOX, then the RF does not begin to decay until
a little over 8ms after key up. So the RF follows the keying pretty much
exactly, except it is all delayed by 8-8.5ms
>The HSEND/VSEND outputs on the
>DIN accessory sockets are the fastest for amp control, and they go low
>about 5-6ms after key-down.
On the 765 the "Send" voltage (+6v rx, 0v tx) follows the keying input
pretty much exactly, with no delay.
...
>So if you use HSEND/VSEND to key the amp, you have about 6ms for the amp
>to get ready.
So with the 765 you have 8.5ms for the amp relays to pull in.
...
>(Or if anyone in my part of the UK is prepared to lend me their MP for a
>day, I'll happily measure it here!)
I just bought an FT1000MP MkV. I no longer work for a company which loans
out digital storage scopes so it's kinda hard for me to make these same
measurements on the new rig. I'd happily loan it to you Ian, but I live in
Canterbury which is over the other side of the country from you. Are you
keen enough to fetch it? :-)
73,
Alan G3XAQ
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