[AMPS] Kenwood TS450 & SB-200??

[Geurts, Gerard]

N1RJ wrote:
> Hi Tom...
> 
> I know you addressed this to Rich but can't resist
> putting in my two cents worth. When I
> was planning to QSK my Drake L-7 amp for use with
> my TS-940, I used a scope with
> triggered sweep to take some measurements. These
> times may not be exact as I don't
> have the info right at hand and am going by
> memory.
> 
> Key down.....scope triggers
> 5 milliseconds....940 starts producing output
> 6 milliseconds...940 at full output
> 15 milliseconds...L-7 relay starts to switch
> 20 milliseconds.. L-7 relay switched after some
> contact bounce.
> 
> As you can see, the 940 was producing full output
> BEFORE the amp relay had even started
> to move! That is HOT switching!!!
> 
I did some similar measurements on a IC709 some time ago to use it with
a QSK amplifier. Used the key line to trigger the scope. From memory it
took a few ms for the amplifier key line to switch, and the 709 started
producing power a few ms after that. No problems with hot switching the
amplifier there, provided the QSK circuit used in the amp is fast
enough. The problem I found was on key up. The amplifier switch line
went high some 10 ms (again from memory) BEFORE the 709 stopped
producing RF! With a fast QSK switch (especially when using PIN diode
QSK) you will be hot switching the amp on key up, not key down. I
e-mailed ICOM tech support here in GB with my findings, and after a
couple of reminders I was told that the switching times I found were
'typical for other ICOM equipment as well'. Beware.

If somebody has done these type of measurement on other ICOM equipment I
would like to here of the findings.

Cheers

Gerard, MoAIU / AA3ES

--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm