Steve,
Well here are the measurements you were asking for (curiosity got the
best of me and I decided to throw a test set up together and see what I
see before going on vacation).
These measurements were done with the new K2 firmware just recently
installed: v2.04P/1.09.
1. In CW mode, 8R Hold= normal with t-r delay set to 0.02 sec
a) 8R goes low and rf starts rising 17ms +/- 1ms later
b) RF starts declining and 8R rises 5ms later. Please note this is a
normal 90%-10% fall time measurement. RF is at 100% output 5ms before
the rising edge of 8R and declines exponentially from that point
in time. At the rising edge of 8R the rf is essentially 0.
2. In CW mode, 8R Hold= normal with t-r delay set to 1.0 sec
a) measurements exactly as above. So I assume that in this set-up
t-r delay means speaker un-mute delay.
3. In CW mode, 8RHold=hold with t-r delay set to 0.10 sec
a) 8R goes low and rf starts rising 18ms later. Same as above
b) RF starts declining and 8R rises 0.10 sec later
c) I tried with t-r delay 0f 0.05sec and for that value RF starts
declining and 8R rises 0.05 sec later.
4. In SSB mode with a constant audio tone injected int to the mic
connector and with PTT keyed using a hand key connected to the key jack
on the back apron, I get the following result:
a) 8R goes low and rf starts rising 18ms later
b) RF starts declining and 8R rises 10 ms later
c) these measurements are independent of the the value of t-r value
and 8R Hold value.
Conclusion is 8R Hold=hold causes 8R to rise t-r delay seconds after rf
starts to decline in CW mode. Otherwise the 8R line's timing is fixed
and as described above.
Hope this helps in your transverter design or sequencer design (if any).
My guess is that you'll be ok with the G5Y's and no sequencer. BTW, in
my hb 2 meter transverter, I use the extra pole on a relay to short the
input of the receive front end to ground when in transmit. This
renders relay isolation much less important. I also key the bias on
the power gain stage to off with an extra relay while in receive (you'd
think grounding the the input of the transmit string during receive
would be enough, but there's enough rf floating around in there that it
isn't... at least in my case.... ymmv).
As for the power level handled by the relays in my hb transverter, its
about 30 watts. I'm dry switching them which should help a lot. I'll
learn by experience, but so far they're surviving.
One other thing I ought to try is to see if 8R Hold = hold/normal value
is stored per band. It would be nice to have quick qsk on HF (I've been
using 20 ms since I built the K2 in 2000) and a much longer delay (say
100 - 200 ms) in vhf/uhf to save the transverter relays.
GL & 73,
Lenny W2BVH
ps- if you get a chance, keep me posted on how things work out for you.
Steve Kavanagh wrote:
Lenny:
It would be interesting to see the
differences in timing (if
any) for the normal mode and what the 8R Hold mode
timing is. BTW I put
a question on the Elecraft list a few weeks ago
about 8R Hold; what it
does any why it should be used in favor of 8R normal
but there were no replies.
The 8R Hold mode holds the 8R line in transmit until
the T-R delay (or VOX delay, I think, but I won't be
using VOX with transverters so I haven't checked)
times out. This reduces relay chatter in transverters
and amps and is there specifically for this purpose, I
believe. I don't think it does anything noticeable
within the K2 itself. I also don't know if there is
any offset in time between the dropout of the 8R line
in VOX mode and any RF output resulting from audio
levels too low to hold the VOX in.
Agreed. I would be a worth while measurement. I'll
try and do that one
too. For that I'd need to rig up a connection to a
new mic plug
connected to a tone generator to watch the rf go
away while keying.
Perhaps for VOX mode testing. In PTT mode you really
need to compare the timing of the PTT line and the RF
output. I would imagine just saying "ahhhhhh" (might
be too low pitched though to count as a steady state
signal for this sort of test) or whistling into the
mic would be sufficient.
I used G5V relays. They are pretty fast and I was
able to get a sleeve
of them pretty inexpensively on ebay. I have a hb 2
meter transverter
that works fb with them and the K2 (with the old
s/w).
Yes, I see they are FAST ! How much RF power did you
put through them on 2m ? I imagine the SWR would be
pretty acceptable for my 6m application (though maybe
not the isolation ?). The G5Y and G6Y are actually
intended for UHF operation and have pretty good
isolation between transmit and receive pins, but they
are a bit slower.
Anyway. Best of luck getting on VHF+.
I've been on (all bands up to 24 GHz) for years...just
trying to upgrade the IF rig and get slightly out of
the QRP category on some bands as well.
When I have more timing numbers
I'll be sure to send them to you.
I'd appreciate that. I'd do it myself if I had a
suitable oscilloscope. It might be worthwhile putting
a little article on Elecraft website. The transverter
stuff there is getting dated (pre K60XV) and doesn't
deal with all the fine details.
Have a good trip !
73,
Steve VE3SMA
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