Intermittent PTT relay in HR500

[K5RHD Randy Diddel]

Hi OM's

I have a KX3 running a HR 500. In the last day or so, the relay in the amp is not activating. The display shows the Mega switching from Green to Red but the usually very audible click of the relay is not there. My W2 watt meter is showing the ~3W drive power through the amp.

About 2 out of 5 times the amp does key properly and I get the power out of the amp. This both into a dummy load and my actual antennas. The amp has been rock solid from day one until this week. Also, using the same KX3, I can key my 2M VHF amp 100% of the time without issue.

Thoughts or ideas on where to start?

73

K5RHD

/randy

[K5RHD Randy Diddel]

I forgot to mention that I have a "Radio Dan" RBI-1A powered relay that gets keyed by the KX3 to eliminate any high current drain issues from the 2M TE Systems amp that I have. Someone suggested off list that a LONGER RCA may be worth trying. 

I welcome any other suggestions....

/randy

[jcve...@gmail.com]

Does the amp key reliable if you activate it by grounding the PTT line?

[jcve...@gmail.com]

So it sounds like there is an issue with the PTT driving signal. Try connecting the KX3's PTT directly to the HR500 and see if the problem persists.

Jim.

[K5RHD Randy Diddel]

Hi Jim,

I moved the key in front of the Radio Dan relay and things seem good. Is it a timing thing where the PTT happens after RF is at the amp? There is a slight delay with the powered relay but this just started in the past few days which is odd.

73

K5RHD

/randy

[jcve...@gmail.com]

Hi Randy,

The PTT is interrupt driven on the HR500 and there is a little bit of debounce time added . RF signal detection triggers an interrupt as well to kick of the frequency counter. I suppose if RF trips of the frequency counter it might be masking the PTT briefly. In general it's bad practice to switch the amp with RF present.

Jim

[Robert Herendeen]

What is the delay at for the KX3's TX DLY setting? Your mechanical relay buffer is adding 5 to 8ms delay to the PTT. 

On Monday, January 22, 2024 at 6:50:22 PM UTC-5 k5rh...@gmail.com wrote:

[K5RHD Randy Diddel]

 Hi,

It is set to NOR (Normal) which I think is 5ms??

/randy