Pulsing transmit power on a FT-900

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Gw0wvl
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Pulsing transmit power on a FT-900

Postby Gw0wvl » 20 Apr 2017, 06:24

I've been running a FT-900 with HRD , Last free version, 4.8 ... The CAT lead came of EBay, A seller I've used many times before ... When i key up on SSB i see a wavering output of some 2-3 watts , This is just a dead key, No Audio ... Unplug the CAT cable and this problem , Well issue really , Is gone ....Now i run a similar set up on my ICOM 706-mk2 ...Same programme , Same PC is used but no wavering low level RF out ... So i would assume it's not the PC causing it ....My only real thinking is that it's possibly the CAT cable , The cat cable is USB to CAT plug, I'm wondering if it's the circuitry that's in the USB socket that causing this , I'm guessing it's something like a RS232 moulded into the usb plug for conversion ..Anyone else have any similar issues ?

Thanks
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andymuza
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Re: Pulsing transmit power on a FT-900

Postby andymuza » 20 Apr 2017, 07:59

What mode of transmission?
What are you reading the output fluctuation on?
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Re: Pulsing transmit power on a FT-900

Postby Gw0wvl » 20 Apr 2017, 08:11

SSB as stated in my post .. Daiwa NS-660-P Peak reading meter ....
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Re: Pulsing transmit power on a FT-900

Postby paulears » 20 Apr 2017, 08:20

So when using the other radio, the only difference is the USB cable? I'd guess RF getting back into the radio via the cable. Tried wrapping a few turns of it through a toroid?

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Re: Pulsing transmit power on a FT-900

Postby Gw0wvl » 20 Apr 2017, 09:52

It's not RF as it's doing it on a Dummyload ... Ile knock up a D-type 9 wAy to Cat plug lead when i get chance and try that , It's possible it's a Ground loop ....
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Re: Pulsing transmit power on a FT-900

Postby Gw0wvl » 20 Apr 2017, 10:06

I can back the power of to zero, And turn back the mic gain to zero and it still does it, It doesn't show it on the meter but on the scope connected to the antenna socket it can still be seen .... But if i turn the power up to 100 watts i can see the wavering output of a few watts on the Daiwa meter.
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Re: Pulsing transmit power on a FT-900

Postby andymuza » 20 Apr 2017, 16:09

Gw0wvl wrote:SSB as stated in my post .. Daiwa NS-660-P Peak reading meter ....


Sorry, glasses must have been mucky.

Try the dead key on SSB with the Mic gain turned off. The mic may be more sensitive than the one on the 706 and may be picking up background noise.

It definitely won't be RF because a dead key on SSB shouldn't produce any due to the lack of carrier.

Also try doing a dead key on FM and see what happens.
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Re: Pulsing transmit power on a FT-900

Postby Gw0wvl » 20 Apr 2017, 17:35

I've already tried with the Mic gain at zero ... As stated ... I'm guessing its possibly a ground loop, Or possibly a Square wave getting back into the radio from the RS-232... Ile also scoops the Cat lead when i get chance , My post was to see if anyone else has had a similar issue using Ng a USB cat lead with a Yeasu , I know my Yeasu is the Ft-900..... I used a 9-way D type to 9 way D type on my FT-2000 ...I didn't get any issues, Again this was using the same PC .... I'm really thinking it's the actual USB cat cable that's the main issue, Especially the RS-232 converter .... Andymuza ... Thanks for your comments matey , Much appreciated.
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Re: Pulsing transmit power on a FT-900

Postby andymuza » 20 Apr 2017, 23:13

Do you know what chip is in the RS-232 converter. I had one that was completely incompatible with HRD and had to buy a later chip version. Chances are you are already aware of this.

I can't for the life of me remember the chip versions but will try and find out.
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Re: Pulsing transmit power on a FT-900

Postby Gw0wvl » 21 Apr 2017, 05:00

No .... I've nothing got a clue as to what chip is in the lead, it's Purpose built lead sold on eBay by a Chap in England .... But as is the case it's made in china , The USB plug is plastic moulded onto the end of the cable along with the Electronics ... So Ide have to cut open the plastic moulding to see what's in it ,. And as it's working i really don't want to do that ...... When i get chance/time Ile scope the pins as there connected to the cat socket, this would mean opening​ up the FT-900 but that no big issue as i had to do that to tap of the 70 MHz IF to run a SDR as a Pan-adaptor.... Originally i thought this was the reason it was pulsing , So i then disconnected it .... But it made no difference....The process of elimination has me convinced it's the actual cat lead that's the issue ..... Its going to be some time next week before i can do anymore tests or checks on the leads and radio .. ..
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