[ICOM] Amp Keying Question Again

Wed Jun 22 22:27:01 EDT 2005

Wouldn't it be better if you added a RC network to the ACC(2) output to hold
the voltage for the switching?

By open circuit, you mean that the Alpha (amplifier) unkeys, and the PRO2
has no load, but is still sending - seems like a method for arcing on the
amplifier relays!

So them the VSWR goes high, and then the ALC reduces the drive, which
*thankfully* reduces the power being sent to the amplifier relay!

I agree that the relay will open later - but it will also close later in the
beginning!

I am confused at how you are able to get the amplifier to key before r.f.
hits it from the ICOM exciter (read "your Icom transceiver") and then delay
with the relay output.

Please if you have such a schematic of a device with does this - perhaps by
diode switching - it will save me a bit of work.

Frankly, I think that the market is ripe for a commercial bucket brigade
device that not only will delay audio, but also delay switching commands
(read:  CW and RTTY).

I know that ICOM and others wish to sell accompanying amplifiers - and I'm
sure they are worth it - but I am on retirement income (read: no money) and
have to make do.

One of the things I don't want to make do with is:  PERFORMANCE.

As a CW operator, radios that were CW radios ended with the separate
radios - transmitters and receivers!  The KWM2 was the beginning of the end!

I would love a sequentially sequenced amplifier - which would key my relay
on the amplifier, then transmit the signal, then delay the relay closure
until the signal ended.

To do this on SSB SSTV and RTTY modes (audio modes) you need a bucket
brigade device which could digitally (ok, analogue guys, you can use a tape
delay!) delay the signal by 20 ms or so, and the same for CW and FSK - but
of course these are just keying pulses.

This would be a wonderful addition to any radio.

73

David J. Ring, Jr., N1EA
Pre-retired Radio Electronics Officer U.S. Merchant Marine

----- Original Message ----- 
From: <paul at w8aef.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Wednesday, June 22, 2005 4:15 PM
Subject: Re: [ICOM] Amp Keying Question Again

With my PROII the RF envelope is delayed by 8ms from the keying line.  I do
have a problem with QSK because the ACC(2) keying line goes unkeyed before
the end of the RF envelope.

When I run my Alpha amplifier during QSK the PROII transmitter sees an open
circuit when the reed relay on the input to the Alpha unkeys and the alc in
the PROII partially shuts the transmitter down for subscequent elements.

The work around is I use the PROII's relay output, which stays closed until
the element is completed.

de Paul, W8AEF

----- Original Message ----- 
From: "David J. Ring, Jr." <n1ea at arrl.net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Wednesday, June 22, 2005 6:58 AM
Subject: Re: [ICOM] Amp Keying Question Again

> How about sequencing, Adam?  When keying from ACC(2) pin 3 of the ICOM
> exciter, does that pin switch at xx milliseconds before r.f. is generated?
>
> In otherwords, can I hook up my amplifier relay to ACC(2) pin 3 have the
> relay be energized and then the ICOM exciter generates r.f.?
>
> I've seen some elegant solutions to hot switching - including a bucket
> brigade delay which divided the voice signal (which activated the VOX)
> into
> two components - the first activated the amplifier relay.  The second was
> time delayed by 20 ms by the bucket brigade digital delay and then fed to
> the microphone input of the exciter.
>
> Thus no hot switching - and no missed first sylables caused by VOX
> clipping
> because the VOX was turned on by the "real-time" speech, but that speech
> was
> delayed digitally and fed to the exciter - so it never got chopped off.
> No
> need to say "ahhhhh".
>
> The problem with some of the digital modes, and CW QSK is that the r.f. is
> hot switched.  I've seen amplifiers that show this damage - it often
> causes
> the relays to arc over and burn up - especially with high power commercial
> installations.
>
> I haven't investigated this with the ICOM radios, I wonder if anyone has.
>
> 73
>
> David N1EA
>
> ----- Original Message ----- 
> From: "Adam Farson" <farson at shaw.ca>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Sent: Tuesday, June 21, 2005 11:13 PM
> Subject: RE: [ICOM] Amp Keying Question Again
>
>
> Hi Dave,
>
> Actually, when keying an amplifier from ACC(2) Pin 3 of an Icom exciter,
> there is no need to disable the reed relay. For example, the Icom IC-PW1
> is
> keyed from ACC(2), and the exciter's reed relay has no function.
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net
> [mailto:icom-bounces at mailman.qth.net]On Behalf Of David J. Ring, Jr.
> Sent: Tuesday, June 21, 2005 15:33
> To: ICOM Reflector
> Subject: Re: [ICOM] Amp Keying Question Again
>
>
> There are some ideas for QSK and speeding up transceiver switching (namely
> eliminating the relays) for some transceivers.
>
> http://www.somis.org/QSK922.html
>
> I am not the author of the page, but the author is held in high regard by
> many.
>
> 73
>
> David N1EA
>
> ----- Original Message -----
> From: "Adam Farson" <farson at shaw.ca>
> To: "'ICOM Reflector'" <icom at mailman.qth.net>
> Sent: Monday, June 20, 2005 1:56 PM
> Subject: RE: [ICOM] Amp Keying Question Again
>
>
> Hi Joe,
>
> The amplifier keying relay in an Icom transceiver cannot be disabled, but
> you may be able to connect ACC(2) Pin 3 (SEND) to the AmpKeyer input. The
> SEND line is bi-directional; it goes low on transmit, and grounding it
> externally keys the transceiver. The relay will still operate, but keying
> from the SEND line eliminates the relay's 1 mS latency.
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
>
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>
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----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/

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