A question of sequencing for 23cm

[VK6OX]

OK, I've read the "TS2000/other sequencing/buffers" thread but reckoned it would be better to start a new thread for my (and maybe others) particular challenge!

I have a TS2000X and wish to drive a PE1RKI 23cm 150W SSPA into a pair of 45el loop yagis. On Rx there will be a LNA. The sequencer is a MiniKits EME166.

Drilling down into a bit more detail:
- the TS2000X DOES NOT have EXTERNAL "tx inhibit" capability.
- the TS2000X DOES have an external ALC control (-7V)
- the TS2000X has the function of delaying tx by up to 25mS on PTT activation.
- the EME166 sequencer has 4 delay O/Ps.
- there will be just one feed to the LNA/antenna array for both RX/TX.
- the SSPA has a separate bias control i/p.
- I have a xfer relay for switching in/out the PA and have a 2nd one which I'm thinking of using at the LNA.
- power to the LNA will be by separate DC feed, as will the "remote" relay.

Soooo....how do I sequence it all, so that I won't blow things up!

Initial thoughts are:

Sequence 1: Bypass the LNA (keep power on).
Sequence 2: Power up the PA (along with bias??).
Sequence 3: Switch PA to TX (relay).
Sequence 4: Release ALC inhibit.

All suggestions/ideas most welcome.

[VK3HZ]

Hi Andy,

A few random thoughts / observations.

You should never power up the PA without a load on the output. So, 2 and 3 should be reversed.

Check that the transfer relay doesn't short the output to input of the preamp when in bypass. The preamp doesn't tend to like that. If it does, you'll need to switch power to the preamp too.

If you can, wire the preamp relay so that it defaults to bypass. That way, if there's a problem and the preamp relay somehow doesn't switch, you don't end up ramming 150W up its rear - they tend not to like that either

Consider running a separate Rx line from the preamp back to the shack as it may simplify switching. It doesn't need to be low loss coax as you've got 30-ish dB of gain in the preamp already. 10dB loss in the coax will not be noticed.

Regards,
Dave
VK3HZ

[VK2JDS]

This is what I do here :
run a separate rx line as Dave suggests, this is the best thing you can do. Use lmr400 or superflex celphone tower heliax from LNA to the PA box.

At the feedpoint use a good relay(one of those 18GHz high power N totsu's etc) with a G4DDK LNA right at the relay, all in a nice waterproof box. Wire it so a single run of figure8 delivers 12volts on receive and switches the relay as well. so on tx the relay is depowered as is the LNA.

use ldf4-50 on tx and suspend 2 loops (1 metre wide loops) at the rotator.

Put the tx power amp in a box at the base of the tower powered by a switch mode power supply. In this box use another coaxial relay (18GHz N or SMA type) to connect to your cable that runs back to the shack and your TS2000x. (I use a IC910h) This relay is powered by the same figure8 run of 12v that switches the mast mounted relay and LNA.

So, we have simplified the TX/RX switching, dropping the 12v rx line First will save the LNA from any damage.

Now the PA needs to be powered up with 28 volts on TX and I use a heavy 12v relay to switch power from the smps to the PA brick. I wouldn't try and keep the 28 volts hot on the fets and use the bias for TR switching as it will end up blowing up if some relay sticks and the amp gets drive without bias....

When you boot up the station :
10MHz gps or rubidium (wait for lock)
your TS2000x on
12v to LNA+relays (big rise in hiss on rx)
turn on 28v SMPS for PA .

going from Rx to Tx sequencing :
Drop Rx to LNA and relays
Send 12v to DC relay for PA
Apply drive from your TS2000x

On CW use the mox button then start sending.
On digital modes use your radio's accessory connector TX input from the serial port adapter whilst dropping Rx dc and switching on PA power. Look in the menu of your chosen digital mode program and find the tx-delay setting. Add an appropriate delay in.
My whole setup runs on batteries and is solar powered. A large 12v bank and a 300 amphour 24volt bank for the PA with isolator switches to turn everything on and off
73 from Dave vk2jds

[VK3QI]

Andy,

Before answering.

Some points of clarification.

(1) Presumably your LNA will be mounted at the antenna

(2) Where will your amplifier be in relation to your TS2000X? Next to it? Base of tower?

Cheers

Peter VK3QI

[VK6OX]

Peter, LNA will be at yagis and PA will be adjacent to TS2000X. My QTH is a suburban lot so I don't have the luxury of space outside.

Thanks to both Daves for their input. Most helpful guys!

The problem I'm trying to get my head around is how to effectively sequence everything (Rx to Tx) by using the rig's PTT to activate the EME166 sequencer.
The 2000X has a max delay before enabling RF of 25mSec...I can't see this as being enough for all the other switching to have taken place beforehand.

Do I need to do it another way?

[VK2OMD]

...

The problem I'm trying to get my head around is how to effectively sequence everything (Rx to Tx) by using the rig's PTT to activate the EME166 sequencer.
The 2000X has a max delay before enabling RF of 25mSec...I can't see this as being enough for all the other switching to have taken place beforehand.

Do I need to do it another way?

Andy, I applied my mind to a project the design a flexible sequencer and looked at the internals of some of the popular radios.

The fundamental problem is that if you cause the transmitter to go into transmit state by any of its available means (PTT on mic, Morse key, paddles, TX button on panel, AUX inputs on the back, CAT/CIV (dedicated connector or USB), mic data stream (eg IC7000) etc) it will create RF output when you are not ready for it.

TXINHIBIT might be a control to modify that, but not all rigs have it and I have not measured its response.

ALC is NOT a useful measure on the radios I tested because there is a considerable delay before removal of external blocking ALC and RF output.

The designers of the radio ought pass the real PTT signal through a connector on the back panel so you can intercept it and over ride it... but most dont, so you may remain at risk of blowing things up because you accidentally pressed mic PTT, or left something connected to an ACC jack.

Because of this architectural failure, I did not proceed with the development because it could not be made bullet proof for the popular radios.

By now, you have worked out that PTT must come from the sequencer, not the mic.

Owen

[VK2JDS]

Let me just clarify what i meant by this in my post from before:
"
On CW use the mox button then start sending.
On digital modes use your radio's accessory connector TX input from the serial port adapter whilst dropping Rx dc and switching on PA power. Look in the menu of your chosen digital mode program and find the tx-delay setting. Add an appropriate delay in."

What I am saying here is by using the tx button on the front of the rig Before you start sending CW you will have given sufficient time for everything to change over. Remember if you are sending cw using break-in and pause a little too long and the rig drops back to rx then your next key-down could be fatal for the LNA. This is why you always use the mox.

If you are running digital modes then there is often a tx-delay built into the settings menu of the software, worth having a look for that as it will give the correct delay you want. Then the tx line will key up but the software wont apply audio until the delay period you chose has elapsed. Doing it this way will stop the software applying audio to the rig before the relays have switched and the sequencer keys up the rig. You could be chopping off the first half second of your data transmission if you get my drift...

When you are running ssb and want to sequence properly without having to pause briefly before speaking then modify the mic cable to the ts2k so the ptt line goes to the sequencer instead of the rig, then have the sequencer tell the rig to go into tx via the accessory connector tx line on the back once the relays have been changed over.

I strongly suggest putting a box at the bottom of the mast containing the PA, PSU and relay to reduce power losses having the PA in the shack.... It also removes a possible source of leaked RF. I had my 150w pa originally on the rack in front of where i sat in the hut, till my rf sniffer pinned its needle at knee height due to rf leaking out of a air-hole, so out it went and up came the power at the antenna too.

73 from Dave

[VK6OX]

<snip>
...
By now, you have worked out that PTT must come from the sequencer, not the mic.

Owen

Hi Owen, yes I had come to that conclusion. Perhaps a simpler solution would be to manually start the sequence to bypass the LNA then power up the PA and then use the transceiver PTT to operate the Tx relay. Will need to give this scenario some more thought tho'.

[VK2OMD]

...

Hi Owen, yes I had come to that conclusion. Perhaps a simpler solution would be to manually start the sequence to bypass the LNA then power up the PA and then use the transceiver PTT to operate the Tx relay. Will need to give this scenario some more thought tho'.

The mic with a working PTT is a loaded gun, and sights are lined up on the LNA.

I don't and haven't used a sequencer, but I have fixed a few LNAs damaged. Excused I hear include "I got exited by a ZL and called him using the mic PTT without thinking", and I was calling someone on HF and I used the wrong mic", "I rebooted by computer and it played TaDa into the SignalLink USB and keyed the tx from the acc jack".

You migth give thought to how you will minimise the risk of those sort of accidents.

BTW, my Signallink USB has a PTT disable switch on the front panel so it can be used to listen without risk of PTT action.

I know of one chap who had spare LNAs for these senior's moments.

And... put in a stock of LNA FETs!

Owen

[VK1JA]

I'm watching this thread with interest as soon I'll be building a 23cm transverter/amp/lna for my TS2000.

Cold the only fool proof way would be to intergrate the sequencer actually INTO the TS2000 and use the PTT button on the mic to start the sequencer and have the sequencer key the radio using the PTT line? Then there could be a potential problem of keying the radio from the rear ACC jack.....

I think the first priority would be to remove power from the relay and LNA on TX, which will take the LNA out of the circuit.

One question - is it best to terminate the input on the LNA to a 50ohm load on TX as well as removing it from the circuit when using around 100w output on 23cm?

[VK6OX]

Dave VK2JDS, my responses to your post embedded below:

Let me just clarify what i meant by this in my post from before:
"
On CW use the mox button then start sending.
On digital modes use your radio's accessory connector TX input from the serial port adapter whilst dropping Rx dc and switching on PA power. Look in the menu of your chosen digital mode program and find the tx-delay setting. Add an appropriate delay in."

What I am saying here is by using the tx button on the front of the rig Before you start sending CW you will have given sufficient time for everything to change over. Remember if you are sending cw using break-in and pause a little too long and the rig drops back to rx then your next key-down could be fatal for the LNA. This is why you always use the mox.

Unfortunately there is only a "Send" button on the TS2K: on CW it transmits a constant tone; FM/AM a cxr; on SSB it's equivalent to VOX. Most digital transmissions use SSB so it may or may not be a possibility, particularly given the delay options within some of the s/w.

If you are running digital modes then there is often a tx-delay built into the settings menu of the software, worth having a look for that as it will give the correct delay you want. Then the tx line will key up but the software wont apply audio until the delay period you chose has elapsed. Doing it this way will stop the software applying audio to the rig before the relays have switched and the sequencer keys up the rig. You could be chopping off the first half second of your data transmission if you get my drift...

A possibility.

When you are running ssb and want to sequence properly without having to pause briefly before speaking then modify the mic cable to the ts2k so the ptt line goes to the sequencer instead of the rig, then have the sequencer tell the rig to go into tx via the accessory connector tx line on the back once the relays have been changed over.

Nah, would rather leave the TS2K as unmodified as possible...at least for the present!! Have already added an Xref card from VK3HZ Dave for ext. 10MHz reference.

I strongly suggest putting a box at the bottom of the mast containing the PA, PSU and relay to reduce power losses having the PA in the shack.... It also removes a possible source of leaked RF. I had my 150w pa originally on the rack in front of where i sat in the hut, till my rf sniffer pinned its needle at knee height due to rf leaking out of a air-hole, so out it went and up came the power at the antenna too.

Understand what ur saying Dave, but that's not a viable option in my situation/QTH. I will give serious consideration to separate Rx/Tx feeds however.

73 from Dave

Appreciate your I/P Dave, thanks!

[VK2CMP]

Just a thought on the issue of the mic and frying LNA's particularly with single feeds between the amp and LNA and also Data Modes.
I built an interface between the IC910H and the Amp that only allows me to use the mic when in voice mode and not data mode i.e your using WSJT and forget that the signalink is feeding the sequencer and go ahead and use the mic to fry the LNA... Switching to Data takes the mic offline. Also the signalink won't TX the 910H and fry the LNA i.e. when using the mic PTT as the input to the sequencer and forgetting to move the input to the amp from the mic to the signalink..
The 2nd function selects Amp or Bypass to allow me to use the IC910H barefoot. This switch locks out the LNA in Bypass and while allowing the IC910 to function without have to use the sequencer. Makes life simple for me and my LNA.
Connections are the front mic socket, rear acc socket, the control box and the amp. Simple but does the job. Hope that makes sense?

[VK2OMD]

...Hope that makes ensue?

Sense?

Ok and good, but your solution might have dealt with only some of the sources of PTT. For example, if you the the TRANSMIT button on the front panel, will it cause problems.

I am not saying what you have done is poor, it is probably a quite good idea... but the designers of these radios do not include features necessary to a bullet proof solution. You might wonder if the designers actually use the radios in the real world.

Owen

[VK4TS]

Hi Owen -

you summed it up with the many ways to engage the transmitter -

for all the work to set up a sequencer the only safe way is to pass the final tx line external to the radio and switch at that point. It may mean cutting tracks in the radio etc but it really needs to be done and the first time you fry the LNA will be enough time to remember as you repair it.

[VK2JDS]

Hi Andy, you could make up an adapter using a inline mic socket and a plug, to connect between the handmic and the ts2k, allowing you to split out the ptt line instead of modifying the handmic cable. that would solve the ptt problem to the sequencer for ssb.

next is the problem of the front panel mox button, instead of using that lets make up a switch in a box to activate the transmit mode using the rear panel accessory connector TX line. that solves the problem for switchover when using cw. test it and see if the radio brings up a carrier in cw mode when you activate tx from the rear panel, you should only see output when the key is pressed, but the set should stay in tx mode while the switch is engaged.

73 Dave

[VK2CMP]

Yep the IC910H is a pain to use with amps etc Owen. As for the MOX tape over it or disconnect it.
Not sure there is only one way? For every persons one way, another will use the radio differently and have different external components connected. For me having the radio permanently firing up a sequencer on a 2/70/23 radio is a pain. Every time you talk on 2/ 70 you need to turn the amp on to get the TX signal back into the radio. Not to mention barefoot. So I took the approach that the TX requests actually are external to the IC910. These signals come from the mic and also the Signalink. So these do not enter the radio now. They go to the box on the amp. The mic does not plug into the radio but an adaptor cable as per Dave's comment. the Signalink PTT also does not go to the IC910. The TX signal (PTT into the radio) comes from the amp or in the case I want to use the radio on 2/70 or barefoot are routed back to the IC910 but in doing so the LNA is locked out.
BTW if your looking for a 90 degree 8 pin mic plug for the adaptor cable Mini Kits is the only place I have found that sell them.
cheers
Mick

[VK6OX]

Thanks for all the inputs so far...keep the discussion going!

I doubt that I'll achieve a foolproof solution, but I do have some ideas that I've gleaned from all the above and other sources. I'll put the ideas to the test and if satisfied, I'll share here.

[VK4TI]

OK, I've read the "TS2000/other sequencing/buffers" thread but reckoned it would be better to start a new thread for my (and maybe others) particular challenge!

I have a TS2000X and wish to drive a PE1RKI 23cm 150W SSPA into a pair of 45el loop yagis. On Rx there will be a LNA. The sequencer is a MiniKits EME166.

Drilling down into a bit more detail:
- the TS2000X DOES NOT have EXTERNAL "tx inhibit" capability.
- the TS2000X DOES have an external ALC control (-7V)
- the TS2000X has the function of delaying tx by up to 25mS on PTT activation.
- the EME166 sequencer has 4 delay O/Ps.
- there will be just one feed to the LNA/antenna array for both RX/TX.
- the SSPA has a separate bias control i/p.
- I have a xfer relay for switching in/out the PA and have a 2nd one which I'm thinking of using at the LNA.
- power to the LNA will be by separate DC feed, as will the "remote" relay.

Soooo....how do I sequence it all, so that I won't blow things up!

Initial thoughts are:

Sequence 1: Bypass the LNA (keep power on).
Sequence 2: Power up the PA (along with bias??).
Sequence 3: Switch PA to TX (relay).
Sequence 4: Release ALC inhibit.

All suggestions/ideas most welcome.

Initially I used one of these http://www.w6pql.com/relay_sequencer.htm , but found with the various relay times problems were arising and on reading this dissertation at www.wa1hco.net/SSA_Controller/Design.pdf , eventually altering the code with a friends help to allow variable timing of four events on the Arduino , cant be that hard if I managed it ok
B