apache-labs.com

Hi folks,
Belated happy New Year.
Wondering if anyone has measured the resistance of the RCA PTT out on the rear of the radio (200D) whilst in TX and then..... in RX ?
Any idea as to what readings can be expected? Should they vary from band to band?

Not sure but think it’s making the amp act a bit weird

73

Here's the schematic for the PTT out circuit on the Orion board. It is similar on the other boards.



It's just a simple FET switch to ground with no internal pull-up. Therefore with PTT not asserted there will be near infinite resistance (an open circuit), and with PTT asserted it will be almost a short.

Thank you Scott.
That’s what I wanted to hear... Perfect !

73

Hello everyone,

I have the anan 100 with amplifier keying issue. The RCA jack on the back of the rig has a dead short on it regardless if PTT is activated or not. As soon as I plug in my RCA cable the amp goes into transmit. I'm assuming there should be infinite resistance at RCA connector when PTT is not activated. The amp works ok with my other rig {FT-1000MP}. Diode D24 on the hermes board is the PTT switching diode could this be the problem, please help.

Alex
W6ACT

Is this new behavior? Or is this from day one?

Sounds like it's time for some continuity checking....checking the diode in-circuit may work....especially if it shows a short.

https://www.fluke.com/en-us/learn/best- ... multimeter

de Mike W9MDB

Hi Mike,

I did the continuity test with my ohm meter at the PTT jack and pin 1 on the 25 pin connector and both show the same result dead short regardless if PTT is activated or not.

Alex
W6ACT

You need to measure that diode. I suspect you may see a dead short across that too.

I didn't look at the schematic but it sounds like short somewhere...solder blob...or some such thing.

Mike

Yes it is new behavior I noticed that the amp was in transmit mode while Anan was in receive

If anyone out here has the Anan 100 could they do a continuity test at the PTT jack while the radio is in receive and while in transmit and post the results for me.

Thanks
Alex

PTT Off -- infinite
PTT On (no power out) - 30 Ohms

Can't say I like the 30 Ohm measurement -- may explain why I sometimes my amp won't kick on.
I may have build my own take-it-to-ground circuit or figure out why it's not a dead short.

de Mike W9MDB

Ok Mike, thats what I needed, 30 ohms is good enough to put your amp into transmit. You answered my question infinite resistance when PTT is not activated. That means I have a dead short somewhere on my PTT out circuit. Probably D24 the switching diode. Thank you very much for your help.

Alex W6ACT

Actually appears borderline to me.
Periodically PTT will stop working and usually doing a tune on the tuner will correct it. Interestingly when I transmit about 6 watts the PTT reading shows 18 ohms.
I have an MFJ-998 doing the PTT control triggered by the ANAN 100.

yup, I found D24 the BAT54 has a dead short on it. WOW how did this happen. SB-220 with soft key upgrade is not the problem. Cheap weak bat54 diode is the problem. This is not going to be a fun replacement.

Alex
W6ACT