[TenTec] QSK w/amplifier

[Dr. Gerald N. Johnson]

On Tue, 2007-04-03 at 21:49 -0500, Wayne Whitman wrote:
> I also sent an email to THP, here is there (very quick) response for
> anyone who was wondering.
> 
> "It is not designed to
> be QSK- compatible but may follow slow semi break-in QSO
> with Rf sensed keying circuit.
> It has some rise time and fall time that means amp holds
> for a second or so after you stop keying."
> 
> Guess that rules that one out.
> 
> Thanks for reading and thinking about it.
> 
> 73,
> Wayne
> K4ELO
> 
> 
> 
> 
> On Tue, 03 Apr 2007 21:12:27 -0500, "Wayne Whitman"
> <wwhitman at fastmail.fm> said:
> > Has anyone run an Argonaut or other low power TenTec transceiver on cw
> > with a Tokyo Hy-Power amplifier?
> > What about qsk?  The THP spec for the 100w solid state amp says it is
> > carrier switched, but I would be more comfortable buying this amp 
> > if I'm not a pioneer.  I'm planning a dx vacation for this fall and I
> > would really rather not haul my Orion along just to get 100w.
> > 
> > Thanks and 73,
> > Wayne
> > K4ELO
> > _______________________________________________
> > 
I can't speak directly about the HF amplifier, but many VHF amplifiers
have a SSB/FM switch on the front panel that sets the time constant of
the RF sensing. Short for FM, long for SSB (and CW). Many times those
amplifiers have a hard key input that keys up faster than the RF sensing
and with the short time constant set FM I've run packet with a fairly
short TXD. And with the hard key control input, the time constant can be
shortened even more to allow for QSK.

The limit is the relay in the amplifier probably isn't made to be fast
and will inherently have at least 15 or 20 milliseconds delay. You
really want it to switch without RF drive else the time with the input
relay between connections will show a high SWR to the exciter and it may
shut down, to say nothing about the poor contact life with hot
switching.

Ideally one could take ANY amplifier, lock it in transmit mode, and
surround it with a set of PIN diode switches that are fast and using the
amplifier key output of many TenTec exciters, key the PIN diodes, wait a
millisecond for them to get fully switched, then key the exciter with
the key input. At least that is available on several and works with high
speed relays in TenTec amplifiers. For that matter, TenTec amplifier
controls could be copied.

There have been PIN diode QSK mod kits made for KW sized amplifiers that
would work with the lower power amplifier too with far greater longevity
at 100 watts than at 1000 watts.


-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer