> Are there two relays in the AL-1200? I guess that was my real question.
> It acts like there is one relay (DPDT format) and I get my alarm when it
> is between connecting the input and output together (STDBY) and when I
> transmit (PTT grounded).
The older 1200 has a standard open frame relay, which is what I
prefer. The contacts are sequenced by slightly bending the output
stationary NO contact up slightly towards the armature.
That simple trick insures the output always closes first and
releases last.
The two-relay system is faster, and uses a constant current
transistor from a 28 volt source to speed the relays up on make.
It also uses some timing components to help assure proper
sequencing.
> With regard to the protection system, I was more referring to the "spike
> ignoring" than the "instant VSWR alarm". I agree that a properly adjusted
> system shouldn't have the VSWR alarm problem. As I know you know, you
> have to adjust products like this for a very broad audience of users or
> you'll get eaten up on the telephone!
The Ameritron ATR-30 has a peak holding meter that responds to
only a few dozen RF cycles. With that meter on a T4XC,
IC775DSP, IC706 or 756PRO my amplifier slams the meter hard
past 3 kW before it drops back to 1500 watts.
If I have a relay out of sequence in a PA, the reflected power needle
(on an antenna, not on a dummy load) will also pin-slam..or at
least read well up on the scale. It actually detects the reflected
power from the arcing contact, which creates energy outside the
normal band.
I imagine your meter does the same.
Ameritron gets about two or three calls a month wanting to "fix the
meter" for those problems.
I think the problem is educating the customers as to what the
meter is showing. Most of them, once they know what is
happening, appreciate seeing the problem. Myself, I like seeing the
reflected power from momentary faults. It lets me fix a problem
before it does major damage.
BTW, the 775DSP I had ran well over 300 watts out before settling
down to whatever power it was set for.
73, Tom W8JI
w8ji@contesting.com
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