Wait a minute!
Who is correct on these radio switching times?
According to Rich , the relays in HENRYS switch too slowly to prevent hot
switching "which is not quick enough to prevent hotswitching with most of
the modern radios."
Of course the FACT that there are very few incidences of relay failure is
not considered, and of those the reasons for failure vary.
Similarly the theoretical specification of how many cycles a vacuum relay
has would have many more of them wearing out than what is discovered in the
real world.
Uh oh, I better not tell my modern radio (TS-870) it is too fast for my
HENRYS! My 3K Classic X MKII was 12 years old when I traded the RF deck back
in for a 3K Premier to get 160M and vacuum out relay.
Never a relay problem, good thing I didn't ask for a theoretical opinion.
Theoretical paper specifications always lose out to real world performance.
If your amplifier is operated on paper then enjoy yourself and specify away,
however use what works and is proven if you want to get out on the air.
73, Dan Magro W7RF, (President WARC 1999, member SCDXC, SCCC)
Manufacturers Rep & Distributor for HENRY RF Power Amplifiers.
www.radiodan.com <http://www.radiodan.com> ??? RFpower@radiodan.com
<mailto:RFpower@radiodan.com> A trip to our web site is worth the click!
> -----Original Message-----
> From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> Behalf Of Dick Green
> Sent: Monday, July 05, 1999 9:25 AM
> To: Rich Measures; Richard W. Ehrhorn; n4kw@citrus.infi.net
> Cc: amps@contesting.com
> Subject: Re: [AMPS]n4kw@citrus.infi.net RJ-iA relay contact-life on CW?
>
>
>
> >Our measurements on popular xcvrs over the past 10 years or so (e.g.,
> >TS-940, TS-950S/SD/SDX, FT-1000D, IC-781) found the shortest
> delay between
> >T/R relay external contact closure (to actuate the amp T/R) and output of
> >initial RF to be ~7 ms. If I remember correctly the 950 was much longer.
> >
> ? Owners of FT-1000Ds have reported seeing RF output at 5mS.
>
> FWIW, my resent measurements of three popular transceivers are as follows:
>
> TS-950SDX -- 15ms
> FT-990 -- 10ms
> FT-1000mp -- 8ms
>
> Unfortunatley, the FT-990 does not activate the T/R line until 7.5ms after
> key closure, leaving only 2.5ms for the amp's relay to close!
> Further, this
> rig cuts the full 10ms off the CW waveform, resulting in very
> choppy-sounding CW in QSK mode and first-element clipping in VOX
> mode. This
> becomes noticable above 20WPM and gets worse as the speed is increased. My
> measurements agree with those that appeared in QST when the 990 was first
> reviewed. Bottom line, unless you use it with a PIN diode amp, safe
> switching with the 990 requires either an amp with built-in T/R sequencing
> (Alpha, Ten-Tec, Amp Supply, to name three) or an external sequencing
> circuit. You have to add some weight to get rid of the choppy sounding QSK
> and first-element clipping. You can do that with a keyer or there's a neat
> interface box described in the April 1987 issue of QST that will take care
> of both the sequencing and weight.
>
> The 950 and 1000mp activate the T/R line immediately upon key closure, and
> should be suitable for use with a vaccum relay amp. The 950 chops about
> 2-3ms off the waveform, which is not audible to me. The 1000mp
> doesn't chop
> anything off. In fact, it looks like the 1000mp might even add a
> ms or two.
>
> BTW, the 1000mp has the cleanest waveform of the three. Rise time is about
> 3-4ms and decay time is less than 1ms. Top and bottom are straight as an
> arrow. The 950 rise time is adjustable from 2-8ms, but there's visible
> overshoot. As I recall, decay time was a little slow but not too
> bad. There
> was a little ripple on the top and bottom of the waveform. The 990 has a
> rise time of about 1ms (very fast!) and decay time of 3-4ms (kinda slow.)
> Small amplitude square waves cruise across the top and bottom of the
> waveform (poor regulation or RFI in some switching circuit?)
>
> BTW, I've not gotten any of Dick's messages on this subject from the
> reflector. I'm only getting them as quoted in Rich's replies. Are
> they being
> sent to the reflector?
>
> 73, Dick WC1M
>
>
>
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>
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