Tom:
The keyer you want is the Logikey Super CMOS III by Bob Locher, W9KNI at
Idiom Press, Box 1025, Geyserville, CA 95441. This unit comes in a partial
kit,
for $58.00. Bob may also some also built up. See August, 95 QST, p. 26 for
details of the keyer.
The unit will do serial # inserts, decrement (if necessary), has four
memories which
can loop or pause as needed for hand sent info, etc. Everything needed by the
contester, dx'er, etc. All this is controlled by the paddle. You can even set
it for speed changes in the middle of the message!! You''ll hear his keyers
a lot at the top contest stations.
You can't go wrong. Page 164 of the March, 96 QST has an ad.
73, Jim W9WU
>From John Brosnahan <broz@csn.net> Tue Apr 9 00:57:53 1996
From: John Brosnahan <broz@csn.net> (John Brosnahan)
Subject: SB-220 stabilization
Message-ID: <199604082357.RAA03543@lynx.csn.net>
>
>I've never added resistors to the filament RF path, and I see little reason
>to do that. I don't know what they do in the anode, so I can't comment about
>that mod. The grids need to be grounded directly, that's an absolute
>certainty.
>
>73 Tom W8JI
>
The technique of adding a parasitic suppressor in the cathode/filament
lead (in cathode driven amps) can help stabilize the amplifier if the
source of the oscillation is a true output to input oscillation
(and at VHF, of course). The advantage of the input side suppressor
is that it is on the driver (100W) side of the loop rather than on the output
(1500W) side of the loop.
73 John W0UN
John Brosnahan
La Salle Research Corp 24115 WCR 40 La Salle, CO 80645 USA
voice 970-284-6602 fax 970-284-0979 email broz@csn.net
>From John Brosnahan <broz@csn.net> Tue Apr 9 00:58:08 1996
From: John Brosnahan <broz@csn.net> (John Brosnahan)
Subject: 4-1000 Info Please?
Message-ID: <199604082358.RAA03559@lynx.csn.net>
I mentioned that Tom and I had taken the 4-1000
super cathode topic off-line and I received a number
of letters wanting to know what the conclusions are.
(Or they wanted to be added to the QRO-reflector if
there was ever such a thing!) So, rather than writing to
everyone that inquired, I thought the following summary
would be adequate.
In summary:
1) Eimac and Eimac emplyees have referred to the
technique of driving the cathode with some additional
drive to the grid in a limited amount of literature. Claims
were made about improvements in IMD. It was never
a popular idea at Eimac.
2) Tom has tried it and was not impressed. To the
extent that he wished the references would just
disappear!
3) I have never tried it, I only mentioned the literature
for informational purposes. After the discussion I
continued to look at the problem and I think the
following summarizes the technical issues.
Super-Cathode-Driven Amplifiers
Implementing the technique with the grid tapped
up on a voltage divider from the plate to ground
(ie 30S1) will work for tetrodes in Class AB1 only.
The technique needs a tetrode for the internal shielding
of the second grid and requires AB1 for maintaining a
constant amount of feedback .
If the tube starts pulling any current the VOLTAGE
dividing ratio is upset by the current and the feedback
is no longer based on the ratio of the two capacitors.
Using the technique with the grid tapped down on the
filament choke will not work over the full HF spectrum
due to the varying ratio of the amount of feedback
caused by the variability of the ferrite over frequency.
In an idealized inductor a tap on the choke should
be just like a tap on an autotransformer and the
voltage should be a simple turns ratio problem.
But ferrite rod filament chokes show similar
effects to antenna current baluns consisting of
stacked ferrite cores. The first core does more
work than the remaining ones making for
an unequal voltage distribution across the
choke. And this variation is frequency dependent,
making it impossible to find one tap that is right for
all of the HF bands.
The technique WILL work for a single band amp.
If a ferrite based filament choke is used some
experimentation with the tap to obtain the right
voltage will be necessary.
Eimac published a design based on a parallel
resonant circuit in the cathode (filament) for isolation
and in this case of an air wound inductor a tap based
on the simple turns ratio worked well. But one would
need to switch in different tuned circuits for each band--
something that isn't really very practical.
Simple Summary = NEVER MIND!
John Brosnahan
La Salle Research Corp 24115 WCR 40 La Salle, CO 80645 USA
voice 970-284-6602 fax 970-284-0979 email broz@csn.net
>From Jeffrey Clarke <jdclarke@freenet.columbus.oh.us> Tue Apr 9 01:25:17 1996
From: Jeffrey Clarke <jdclarke@freenet.columbus.oh.us> (Jeffrey Clarke)
Subject: Contest Free Zones!
Message-ID: <Pine.3.07.9604082015.A14236-b100000@acme>
On Sat, 6 Apr 1996, Jeff Bouvier wrote:
> Contest free zones can easily be found. 10, 18, 24 MHZ. !
> If anyone starts in on this contest free zone crap tell them what
> frequencies are available.
> Flame suit not needed. I can use the heat in RI, 2-4 inches of
> snow predicted for tomorrow night.
>
> 73, Jeff Bouvier k1iu@ids.net
>
I TOTALLY AGREE WITH JEFF. You can also add 40 meters to that
list during the DX contests. I really get sick and tired of these
guys blaming contesters for all the problems on the bands. I think
think that contesters are the elite as far as operators in ham radio.
If a REAL emergency ever occured any contester would be 100 % more
efficent then these space cadets !!
Just my opinion Jeff KU8E
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* Jeffrey D. Clarke jdclarke@freenet.columbus.oh.us *
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