"Hang Time" is confusing for many because it has been used in two different
ways.
Jim's definition was the original, even used in the days before we had
transceivers.
There is a second delay or hang time which only affects the receiver's
recovery time.
I believe Ten-Tec first used the term here.
To avoid confusion, years ago I started using the terms "pre-dit delay" and
"post dit delay" when referring to the transmitters' time sequencing. I
like "hang time" (in its original meaning) better, but it can confuse people
who are only familiar with the other meaning.
Back in the 70s we were testing this stuff and determined that up to about
25ms delay time (both pre and post dit), a human could listen to his own
transmitted tone and still send good CW, but once you delayed a little
longer than that, at speeds of 40 wpm or more you could no longer listen to
your transmitted tone. Your brain just couldn't cope with the delay; so you
had to use a sidetone generated from the keyer rather than listening to the
transmitted signal.
Obviously the mileage may vary from one op to another, but those are
ballpark numbers.
The REAL solution would be for Ameritron and any possible others to stop
using 1920s technology in their amps and use vacuum relays. The transceiver
OEMs could set the pre-dit delay to 10ms, the post dit to 12ms, and everyone
would be happy. In fact there are ways to speed up the vacuum relays that
they switch in about 2ms but it's tricky. Remember, the reverse diode also
adds 2ms, so you have to do some fancy footwork, which is explained by Rich
Measures on his web site. If they all do that, then we could drop
transceiver delays back to 4 or 5 ms.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Wednesday, September 24, 2014 10:52 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] din connector, etc.
On Wed,9/24/2014 1:15 PM, Lee WA3FIY wrote:
> Ahhhhh....... where do you get that Jim?
Three good ways, depending on your resources. 1) RTFM for the product
involved. 2) Hook up a dual trace scope so that one channel looks at the PTT
line and the other looks at the RF waveform, then send dits and sync the
scope to the PTT signal, and read the delay. 3) Download and study the ARRL
Lab report for the product in question, which does a similar measurement.
I just looked at one of my K3s -- TX Delay can be set in 1 msec increments
from 8 to 20 msec. 8 msec is the default. The FT1000MP manuals went with
the radios when I sold them, but I just looked at a summary of menu
settings. It looks like the MP is variable from 0 to 30 msec, with 5 msec
being the default. I looked at the ARRL lab test report for the TS850. One
division on the scope trace is 20 msec, and the delay looks like about 8
msec. I clearly remember that the K2 provided a delay of 8 msec from an RCA
connector on the back of the amp module, and I used it quite successfully to
drive the PTT input of my Titan.
> Various Ten-Tec, Elecraft, and Yaesu radios all have Rx to Tx
> turnaround times of at least 16mS (Eagle) to 36mS (FT5000) with other
Ten-Tec's and Elecraft in between.
Go back and read that spec more carefully where you see it listed -- in the
TS850 review, there's a spec for TX to RX turnaround, which is simply the
hang time, and yes, it's about 17 msec. VERY different characteristic. What
I'm calling "hang time" is how long the T/R relay stays in TX mode.
73, Jim K9YC
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