[Moon-Net] IC-9700 switching

Marshall-K5QE k5qe at k5qe.com
Tue Sep 3 04:18:59 CEST 2019


Hello all....I tried this scheme(putting -4VDC on the ALC) as a method 
of "transmit inhibit".  What I was trying to do was to not allow any RF 
to be produced until I was ready.  Unfortunately, it took 2-3sec for the 
ICOM Pro2 to recover from the ALC blocking voltage.  This was not 
acceptable, so I finally dropped the whole thing.  Other rigs might 
recover more quickly....so your mileage may vary.

73 Marshall K5QE

On 9/1/2019 1:34 PM, Chris, PA2CHR via Moon-net wrote:
>
> Hi All,
>
> I have good results with using  negative ( -4 volt DC )  at the ALC 
> connection, pin #  8
>
> Have the -4 volt connected during RX  ( No output at all) and use a 
> small relay to switch this off with the ‘last port ‘ of your sequencer.
>
> I use 3 sma relays (one for each band) to have separate RX/TX  
> possibilities.
>
> The PTT out, pin # 3,  is connected to the centre of a 3 way switch  
> for activating one of the 3 sma relays:  on the band you want to TX.
>
> This pin # 3 is also  the input for my sequencer: take care: max  200 mA !
>
> 73’s,  Chris, PA2CHR
>
> *Van:*Moon-net [mailto:moon-net-bounces at mailman.pe1itr.com] *Namens 
> *johan.van.de.velde via Moon-net
> *Verzonden:* zaterdag 31 augustus 2019 13:14
> *Aan:* Conrad PA5Y; Peter PA2V
> *CC:* moon-net at mailman.pe1itr.com
> *Onderwerp:* Re: [Moon-Net] IC-9700 switching
>
> Conrad's suggestions seems the most sensible to me.
>
> The main relay at the antenna is 50/20ms and its the first thing to 
> switch after getting PTT from mic or pc or footswitch.
>
> 25ms later my 2nd relay switches ( input port protection of the 
> preamp), and preamp switches off
>
> At 50ms the amp keys
>
> At 75ms the PTT from pc keys the rig (software has an audio delay)
>
> At 100ms the PTT from the mic keys the rig.
>
> Using the vhfdesign seqencer.
>
> Using split rx line.
>
> My 2 cents.
>
> Johan
>
> On4iq
>
> Verzonden vanaf Samsung-tablet.
>
> -------- Oorspronkelijk bericht --------
>
> Van: Conrad PA5Y via Moon-net <moon-net at mailman.pe1itr.com>
>
> Datum: 31/08/19 08:48 (GMT+01:00)
>
> Aan: Peter PA2V <peter at pa2v.com>
>
> Cc: moon-net at mailman.pe1itr.com
>
> Onderwerp: Re: [Moon-Net] IC-9700 switching
>
> I measured the TX delay on PA2CHR’s IC9700 and it was 34ms, my Dow Key 
> 402A relays take 20ms to change state and for ground bounce to settle 
> – BUT- why don’t people just have the radio go over last by driving it 
> with an external sequencer? I drive the sequencer with either a 
> footswitch,  a PC ,  a microphone PTT or a Winkey CW interface. The 
> final 5^th position on the sequencer drives the radio PTT. The 402A 
> relays have auxiliary contacts and so I use these contacts to 
> interrupt the radio PTT. It is impossible for the radio to go into TX 
> if the main LNA protection relay is not in the correct position.
>
> This is absolutely fool-proof and simple.
>
> Using the radio to start a PTT sequence is just asking for trouble in 
> my opinion.
>
> Of course you could use 2 PIN switches for RX/TX separation if your 
> LNA has sufficient gain to overcome the losses.
>
> 73
>
> Conrad PA5Y
>
> *From:*Moon-net <moon-net-bounces at mailman.pe1itr.com> *On Behalf Of 
> *Peter PA2V via Moon-net
> *Sent:* 30 August 2019 15:57
> *To:* moon-net at mailman.pe1itr.com
> *Subject:* [Moon-Net] IC-9700 switching
>
> I am playing with a better TX/RX delay on my IC-9700.
>
> Maximum delay on the rig is 30 mSec, which is a little short.
>
> Most coax and other relays need a longer timing.
>
> I am afraid to kill the preamp with no other protection included.
>
> With this in mind I did some experiments with an (old)  Mitsubishi 
> MD001H hybrid antenna switch.
>
> Using such a device is easy to delay TX RF entering to the relay box 
> and preamp.
>
> It also create a separated RX and TX port.
>
> I also used a circulator at the rig to prevent high SWR on the rig 
> itself during the time there is no connection to the antenna while the 
> Mitsubishi switch delays it.
>
> It really works great, timing on a pin switch can be done in many 
> ways. For this experiment I used a RC combination with an ordinary 
> P-channel FET to switch the bias on the Mitsubishi PIN switch.
>
> As stated before it works and any delay can be made this way without 
> damaging the rig.
>
> After rough tests I would like to know the RF performance of my 
> creation. And I was in shock.
>
> The data sheet said that the minimum isolation between the TX and RX 
> port is 30 dB.
>
> But I measured 23 dB with a calibrated VNA. Another MD001H gave exact 
> the same performance, and another PCB with better separated 
> connections did not gave better performance.
>
> Using the 9700 as an exciter it will drive my amps with around 7-8 
> Watt. Which means that my preamp will have around 70 mW on the output 
> port, and kill the preamp sooner or later with such a low isolation of 
> the PIN switch.
>
> I do not go on with the MD001H, but would like to know if there will 
> PIN switches available that are able to transfer up to 20 Watt and 
> have at least 40 dB isolation between TX and RX ports?
>
> If so, please drop me an e-mail.
>
> 73, Peter PA2V
>
>
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>

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