Since my post yesterday, I've had several inquiries relating to the method I
use for sampling my R.F. output into my scope. Although, there are much
cheaper (homebrewed) alternatives using simple inductive loops, I purchased
a Bird Model 4275-030 wide-band, adjustable RF coupling probe. It provides
for a variable, unrectified sample on my transmission line, and is coupled
directly to the output of a Bird 43P wattmeter. The Bird coupler is rated
at 1KW and has never been problematic at 1500 watts output, even when
sampling into high V.S.W.R. lines. You can view the full specs of the
coupler at: http://www.bird-electronic.com/home.htm
-Paul, W9AC
-----Original Message-----
From: Paul Christensen <paulc@mediaone.net>
To: measures <2@vc.net>; AMPS <amps@contesting.com>
To: <amps@contesting.com>
Date: Thursday, May 18, 2000 2:49 PM
Subject: Re: [AMPS] QSK5 Unit
>Until I started experimenting with QSK timing, I never used a scope. Now,
I
>leave it on-line all the time and I would never do without it. It's
>interesting to not only hear, but see the effects of an amplifier's
>electronic bias circuit on a keyed waveform. I should have mentioned that
I
>also use an accelerated "speed-up" circuit on all my amplifier's vacuum
>relays. Between the speed-up circuit and the auxiliary open-collector,
I've
>never seen hot-switching on my scope. A good acceleration circuit coupled
>with a Kilovac HC-1 is tough to beat.
>
>Incidentally, Kenwood makes a great, "near lab quality" scope in their CS
>series. I have a CS-4125 which I believe sells for around $380 from Print
>Products International ( www.prodintl.com ). It's accuracy and resolution
>is far better than the ham-oriented monitor scopes.
>
>-Paul, W9AC
>
>-----Original Message-----
>From: measures <2@vc.net>
>To: Paul Christensen <paulc@mediaone.net>; AMPS <amps@contesting.com>
To: <amps@contesting.com>
>Date: Thursday, May 18, 2000 2:29 PM
>Subject: Re: [AMPS] QSK5 Unit
>
>
>>
>>>I think the speed you need depends on whether you can get a good early
>>>'transmit' signal from your exciter
>>
>>As an alternative, I presently use a CMOS II keyer with an "auxiliary"
>>open-collector transistor to ensure that the amp is keyed fractionally
>ahead
>>of the transceiver. The primary keyer output connects to the transceiver
>>key jack in a bussed arrangement to all my transceivers. Then, the
>>auxiliary open collector is run in parallel with the transceiver's
external
>>amp relay or open-collector. In effect, I have a key bus of
open-collector
>>outputs that run into all my amps. With the bussing technique, I do not
>>need to worry about switching or directing the control of my amps; it's
all
>>automatic and transparent to me and hot-switching is avoided at all keying
>>speeds. The keyer's auxiliary output ensures that the amp "makes" fast
>>enough, then the transceiver's own amp key line ensures that the "break"
is
>>adequately long to avoid hot-switching on waveform's trailing edge.
>>
>? A break delay necessarily subtracts from the next make. QSK has way
>more gotchas than it looks. An o'scope is indispensable.
>
>cheers, Paul
>
>- Rich..., 805.386.3734, www.vcnet.com/measures.
>end
>
>
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