[ICOM] Amp Keying Question Again

[paul at w8aef.com]

----- Original Message ----- 
From: "David J. Ring, Jr." <n1ea at arrl.net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Thursday, June 23, 2005 2:27 AM
Subject: Re: [ICOM] Amp Keying Question Again


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

This would work if IC3501, an HD64F2357F20 has an open collector output. 
Where can I look for information on this device?

If it lacks an open collector output cutting foil traces and adding steering 
diodes in the radio would be required.  And cutting foil traces on a printed 
circuit board designed for surface mount components and minimum interface 
cabling is not for the faint of heart.  And if the circuitry were added 
externally and a non-Icom radio were used with that external circuit 
everything would be screwed up in the opposite direction.  The problem is in 
the Icom and should be cured in the Icom.

> 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!

Yup.

> 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!

It does, by 8ms

> 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.

As I said in my first posting, "the RF envelope is delayed by 8ms from the 
keying line.  Maybe I should have said: "Both the leading edge and the 
trailing edge of the RF envelope is delayed by 8ms from the keying line, 
which means if I use the keying line to operate the relays in the amplifier, 
the amplifier relays will operate 8ms less bounce time BEFORE the rf 
envelope hits it from the Icom and release 8ms BEFORE the end of the rf 
envelope from the Icom?"

> 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.

Just use the amplifier relay output on the Icom.

> 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!

And we built our own transmitters and receivers because we could not afford 
the Collins.

> 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.

I believe the Alpha 77 and 78 (and probably others) does just what you want. 
You plug your key into the amplifier and the amplifier in turn keys the 
exciter and detects the RF output to keep the relays closed as long as RF is 
present.  And you'll love those amplifiers.

> 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.

The side tone or monitor output would drive you nuts.  We used to build 
speech therapy machines that would delay audio playback by an adjustable 
amount.  A great way to cure a stammer or stutter.

> This would be a wonderful addition to any radio.

Of course you could take the monitor output ahead of the speech delay but 
that would no longer be a monitor output.  You have a great idea for an 
easily designed and built after market device and it would augment your 
retirement income.

Everything has a price.

> 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