[RTTY] Yaesu FT-920 setup - HELP!!

[Tom Homewood]

I am pretty sure when I was fighting the PTT issue I had, I measured the
current when I grounded the PTT pin on the back of the 1000mp and got in the
neighborhood of 10 ma. I tried at least two optos in the circuit with no
luck. I did not try to change the drive to the opto. These resistor in the
RTS line was either 680 or 1K. When I replaced the opto with a 2n2222 all
was well.

73, Tom, W1TO

----- Original Message ----- 
From: "Ian White, G3SEK" <G3SEK at ifwtech.co.uk>
To: <rtty at contesting.com>
Sent: Tuesday, July 13, 2004 6:46 PM
Subject: Re: [RTTY] Yaesu FT-920 setup - HELP!!


> John Fleming wrote:
> >
> >> To repeat a previous message, I've had no problems with two - no, make
> >> that three - different types of regular non-Darlington opto-isolators
> >> keying the PTT, CW and FSK inputs of an MP. It would be very surprising
> >> if the 920 required different levels, since all that generation of
Yaesu
> >> HF rigs are re-using a lot of the same circuit technology.
> >
> >Ian, what "regular" optos did you use?  I've heard of some successes, but
> >not with the 4N-series, e.g. the 4N25.
> >
> Devices that I either know personally, or know of, that have
> successfully keyed various inputs of the MP from a PC's RS-232 ports
> include:
>
> CW :
> 4N33 (Darlington, CTR 500% @ 10mA) with 560R input resistor
> 4N36 (transistor, CTR 100% @ 10mA) with 470R input resistor
> MCT5211 (transistor, CTR 110% @ 1mA) with 1k input resistor
> FSK :
> SFH618-A3 (transistor, CTR 100% @ 1mA) with 2.2k input resistor
> TIL117 (no details handy) with 2.2k input resistor
>
> CTR = current transfer ratio, which is the opto-isolator's version of
> "gain".