Look at W8ZR's excellent article in the current issue of QST.
73,
... Joe, W4TV
On 2015-05-31 2:50 AM, Vic Rosenthal wrote:
Agreed. With a K3 you don't need any special sequencing -- just replace the
relay with a reed relay for input and a vacuum relay for output (or two vacuum
relays). It is much more pleasant even if you don't use QSK or VOX.
Vic 4X6GP/K2VCO
On May 31, 2015, at 7:21 AM, Guy Olinger K2AV <[email protected]> wrote:
Expecting a transceiver to somehow neutralize all amp obsolescence is
putting the burden where it doesn't belong. And it really can't come
close to doing the entire job.
Existing mod kits from Harbach, W7RY, etc, can convert many older amps
internally (all the way back to SB200 SB220) to *excellent* modern
status, QSK, modern interface voltages and behavior, good for years of
slick operating to come. Array Solutions has an excellent external QSK
device, for those who don't want to tackle an internal mod.
You didn't say which specific amp with slow frame relays. Many (most?)
of these were designed back when the expectation was something like a
footswitch or a toggle switch would be used to place the shack in
transmit mode.
I own an FT1000MP. On CW (only) it has a first in first out bucket
brigade delay (menu 7-4 keyer break-in time) which allows it to apply
T/R assert to the amp and allow continuously delayed CW up to 30 ms to
be transmitted from the MP. With the clunkier amps actually needing
the max 30 ms delay like my older AL1200, you had to listen to the
input monitor on the MP if you were sending with a key. Listening to
the actually sent signal would is so divergent from physical input at
30 ms that many simply can not send CW with it.
But it doesn't fix the parallel problem on SSB.
Even if the MP's delay was working OK for CW, there is no delay for
SSB. This would require a continuous bucket brigade voice delay with
sufficient fidelity. That isn't impossible, but a lot more expensive
and complex than a faster relay. And it STILL does NOT fix all the
issues of clunk involved. This includes the recovery time from T back
to R so slow that in contests often the first baud or two of a reply
would be lost while the relay is waiting for the contacts to restore
the RX path through the amp, which now only has the spring to propel
points to normally closed state.
IMHO to put it bluntly, any amp relay with T/R duties that won't close
in 8 ms is obsolete and needs to be replaced by something modern.
The aftermarket mod boards will modify old tube amps for QSK, low
voltage low current T/R keying (soft key), step start power-on etc.
Amps modified with current QSK circuitry will switch quickly enough to
support VOX on SSB. All the Ameritron amps have superior aftermarket
QSK mods available, in addition to the manufacturer's own QSK option.
W2CS helped me QSK my AL1200 with the same circuit he used to upgrade
his SB220. This was before the current crop of excellent mods were
available. No excuses.
73, Guy K2AV
On Saturday, May 30, 2015, David Raymond <[email protected]> wrote:
I'm running an older borrowed K3 to get various I/O issues worked out while
awaiting arrival of my K3S. I am interfacing the K3 into an older tube amp
with large open frame relays for antenna IN and OUT. The maximum TX DELAY
limit of 20 ms on the borrowed K3 is not enough to avoid hot switching the amp
output relay contacts. I had the delay in my old FT1000MP set for 30 ms which
was adequate with some margin (it had a max delay of 40 ms I believe). Are
there any options in newer K3's for more than 20 ms of TX DELAY? Hopefully the
K3S will have more than 20 ms or my options for QRO are QRT. . hi. 73.
. . Dave, W0FLS
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