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 One For The IC-9700 Owners 
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Post One For The IC-9700 Owners
Have any of you 9700 owners managed to get it to work with a linear-amp., and a masthead pre-amp on digi modes?
At the moment I have it PTT-ing my HA1YA amp OK. The 30 millisecond PTT delay seems to be enough to switch the amp. to TX before the radio starts to transmit digi tones. I can hear the relay in the amp. switching over before I hear the tones.
I want to use a SSB SB 2000 pre-amp and DC2004 B controller, but it would seem that the pre-amp would be hot-switched after the 30 millisecond delay, i.e. the radio would be transmitting while the relays in the pre amp. are changing over.
I can see how to do it safely when using SSB or CW by having the sequencer PTT the radio.


Tue Sep 15, 2020 2:54 pm
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 One For The IC-9700 Owners 
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Post Re: One For The IC-9700 Owners
Does the amp have its own sequencer or bias t output for the preamp?

With the gemini amps, you use a foot switch to key the amp which has a sequencer internally to switch the bias t and key the radio at the right time.
It uses a sequencer which is fully configurable and available to buy as a kit or fully built.
Used them in other amplifiers with great results.

The 9700 should stop transmitting before dekeying the amp and sending bias t up the antenna lead so Ive deduced from the manual.
But I suppose LinAmpUk recommend their way for a reason.

I suppose you could wire up some leds to the ptt lines and see what happens.

Mark

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Tue Sep 15, 2020 3:14 pm
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 One For The IC-9700 Owners 
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M1MPW wrote:
Does the amp have its own sequencer or bias t output for the preamp?

With the gemini amps, you use a foot switch to key the amp which has a sequencer internally to switch the bias t and key the radio at the right time.
It uses a sequencer which is fully configurable and available to buy as a kit or fully built.
Used them in other amplifiers with great results.

The 9700 should stop transmitting before dekeying the amp and sending bias t up the antenna lead so Ive deduced from the manual.
But I suppose LinAmpUk recommend their way for a reason.

I suppose you could wire up some leds to the ptt lines and see what happens.

Mark


Hi Mark,
The linear amp. doesn't have a sequencer or bias-Tee, but the SSB Products DCW2004 B sequencer does.
A foot switch or hand-held PTT will work fine in non-digi-modes, as does the hand mic. PTT. I have that sorted.
I'm trying to get it to work with WSJT (X) modes where the radio is PTT-d by the WSJT software via CAT control.


Tue Sep 15, 2020 3:36 pm
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Hi Stewart

Does the 9700 have an External ALC input ?

If it does it'd be pretty easy to feed it with the full ALC Voltage required (guess something like -4V or -8V) and only have it removed on the last sequence (obviously reapplied immediately when going back to RX as the 1st stage).
This would effectively hold the TX Output off until all has been switched over. A simple circuit added to the sequencer would keep it to the individual band in use if needed.

I have used this method on Kenwood radios with no issues, on my Yaesu kit I use a similar method utilising the TX INHIBIT input which holds back any RF until the sequencing is complete.

Not wanting to state the obvious but do ensure sequencing for all possible methods of the Rig going into TX - i.e. mic, key, pc Once upon a time I thought i'd covered all my options only to discover that my radio at that time went to tx when the key was pressed without grounding the PTT line - one accidental tap & poff bang went a FET :)

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Tue Sep 15, 2020 3:38 pm
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 One For The IC-9700 Owners 
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F4VPC wrote:
Hi Stewart

Does the 9700 have an External ALC input ?

If it does it'd be pretty easy to feed it with the full ALC Voltage required (guess something like -4V or -8V) and only have it removed on the last sequence (obviously reapplied immediately when going back to RX as the 1st stage).
This would effectively hold the TX Output off until all has been switched over. A simple circuit added to the sequencer would keep it to the individual band in use if needed.

I have used this method on Kenwood radios with no issues, on my Yaesu kit I use a similar method utilising the TX INHIBIT input which holds back any RF until the sequencing is complete.

Not wanting to state the obvious but do ensure sequencing for all possible methods of the Rig going into TX - i.e. mic, key, pc Once upon a time I thought i'd covered all my options only to discover that my radio at that time went to tx when the key was pressed without grounding the PTT line - one accidental tap & poff bang went a FET :)


Hi Kelvin, Yes it does have an ALC input on pin 8 of the accessory socket, but the linear amp. doesn't have an ALC out. Pin 3 on the socket can be PTT in or PTT out (clever).
I've read many moans on the various 9700 groups, complaining about the radio not having separate PTT out for each band. It's easy to accomplish that with a simple 3 position manual switch. No need for a fancy auto-detect circuit to select PTT for whatever band. I'll have a trawl through the forums to see if anyone has accomplished what I want to do already.
I know all about blowing-up a pre-amp. Been there; done that.
The whole thing is straight forward to accomplish on my TS-B2000, using a Signalink USB, and I could revert to using the 2000 for digi-modes, but I do like the 9700, and I'd like to use it.


Tue Sep 15, 2020 4:03 pm
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Hi Stewart

My method is not to use a variable ALC feed from amp or similar, but rather supply the voltage to the radio at it's maximum value to suit the radios ALC range from a little circuit (79L08 or similar to suit the ALC voltage range of the radio)

This way while the voltage is supplied to the radio it's output is held at nigh on zero even if it goes into TX (on my TS2k I could not detect any RF outout when in transmit), and by using the final timed stage output of a sequencer to feed a relay or solid state switch as a way of removing this voltage and then back on again to enable & then inhibit the actual RF output of the radio when needed.


Feel free to contact me off site if I can be of help.
73

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Tue Sep 15, 2020 4:51 pm
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Been a while since I used digital modes ......but doesn’t WSJT MSHV Etc have built in delay after it switches the PTT Before it puts audio onto the signal .....this allows everything to go to tx before audio applied

Or maybe I dreamt it .....

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Tue Sep 15, 2020 6:49 pm
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Isn't the point of the dc2004b to interface with the amp and preamp and sort it all out,

I haven't used one in years but thought it did,

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Tue Sep 15, 2020 9:56 pm
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G4HTZ wrote:
Been a while since I used digital modes ......but doesn’t WSJT MSHV Etc have built in delay after it switches the PTT Before it puts audio onto the signal .....this allows everything to go to tx before audio applied

Or maybe I dreamt it .....


I thought that too, but I can't find any reference to it in the destructions.


Wed Sep 16, 2020 6:29 am
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ei2glb wrote:
Isn't the point of the dc2004b to interface with the amp and preamp and sort it all out,

I haven't used one in years but thought it did,


Exactly, but the problem is that the TX/RX periods are controlled by the WSJT software, so how do you get the software to PTT the sequencer? It uses CAT control to PTT the radio.
I'm probably missing something obvious.


Wed Sep 16, 2020 6:33 am
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gm0gtu wrote:
G4HTZ wrote:
Been a while since I used digital modes ......but doesn’t WSJT MSHV Etc have built in delay after it switches the PTT Before it puts audio onto the signal .....this allows everything to go to tx before audio applied

Or maybe I dreamt it .....


I thought that too, but I can't find any reference to it in the destructions.


Go to page section 4.8 ...under advanced you can set tx delay ....think default is 0.2s .....
Hope that helps ....I used to use a Gemini linear with power over cable to a mast head amp and never blew it up on WSJT modes ....famous last words .

http://physics.princeton.edu/pulsar/k1j ... l#ADVANCED

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23cms ..IC9700..vhf design 350w amp ...homemade masthead amp ...36 ele antenna amplifier yagi
24ghz ...IC9700 .DB6NT transverter , 2w.. 60cm dish .
10ghz ...IC9700 DB6NT transverter 12w 80cm dish
MM0CUG 12m mast

Mainly listening on HF With RACAL RA17


Wed Sep 16, 2020 9:44 am
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G4HTZ wrote:
gm0gtu wrote:
G4HTZ wrote:
Been a while since I used digital modes ......but doesn’t WSJT MSHV Etc have built in delay after it switches the PTT Before it puts audio onto the signal .....this allows everything to go to tx before audio applied

Or maybe I dreamt it .....


I thought that too, but I can't find any reference to it in the destructions.


Go to page section 4.8 ...under advanced you can set tx delay ....think default is 0.2s .....
Hope that helps ....I used to use a Gemini linear with power over cable to a mast head amp and never blew it up on WSJT modes ....famous last words .

http://physics.princeton.edu/pulsar/k1j ... l#ADVANCED


That's it Steve. Thanks mate.
How the H**l did I miss that?


Wed Sep 16, 2020 10:09 am
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Easily missed ...I couldn’t find it .....even thou I knew it existed somewhere....
Hope it helps
Cheers
Steve

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24ghz ...IC9700 .DB6NT transverter , 2w.. 60cm dish .
10ghz ...IC9700 DB6NT transverter 12w 80cm dish
MM0CUG 12m mast

Mainly listening on HF With RACAL RA17


Wed Sep 16, 2020 10:57 am
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