[Moon-Net] IC-9700 switching

Chris, PA2CHR post at pa2chr.nl
Tue Sep 3 10:00:01 CEST 2019

Hi Marshall,


It also did not work with my IC7100  L

But it is OK with the IC9700  J


Vy7 3’s,

Chris, PA2CHR


Van: Moon-net [mailto:moon-net-bounces at mailman.pe1itr.com] Namens Marshall-K5QE via Moon-net
Verzonden: dinsdag 3 september 2019 4:19
Aan: moon-net at mailman.pe1itr.com
Onderwerp: Re: [Moon-Net] IC-9700 switching


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.







Verzonden vanaf Samsung-tablet.


-------- Oorspronkelijk bericht --------

Van: Conrad PA5Y via Moon-net  <mailto:moon-net at mailman.pe1itr.com> <moon-net at mailman.pe1itr.com> 

Datum: 31/08/19 08:48 (GMT+01:00) 

Aan: Peter PA2V  <mailto:peter at pa2v.com> <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 5th 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.




Conrad PA5Y


From: Moon-net  <mailto:moon-net-bounces at mailman.pe1itr.com> <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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