Cobra 29 ltd modulation light mod

[Eldorado828]

Stumbled across those video and thought this is actual a cool looking little radio. One thing that really caught my eye was the mod led. Does anybody have info on that modification? I've seen it on the 98vhp and others before but never seen it on a 29.

 

[Handy Andy]

older cobras came with MOD option - using the UNIDEN board - before they went to KEPC

 

[Enterprise312ok]

You could use the swr warning light circuit, they act just like a mod light after you turn up a cobra 29

 

[NZ8N]

The old 29 - 23 Channel radio had the Mod light, the 29GTL and 29LTD and newer did not. It would be an easy mod to add a Mod light circuit to any radio. Just would need to figure where to mount the light. Parallel with the Meter light? Or change from bulb to LED??

 

[Enterprise312ok]

I like mod lights, I was happy to find the 95t I just got my hands on has a working mod light, that makes it a keeper and my old realistic trc-47.

 

[TM86]

Looks like it flashes on RX and TX. So probably hooked into the audio circuit, maybe via a buffer amp to not load the audio circuit down. It's a neat bit of eye candy.

 

[NZ8N]

The video does, but the one in the old Cobra 29 shouldn't, it has an RF sniffer with a 5pf cap sampling RF output on TX, to "turn on" TR23 that turns on the Mod lamp. Modulation positive peaks increase the voltage feeding the mod lamp, thereby brightening it. No RF, no light.

 

[grimace]

I've never added a mod light before but I have added a modulation meter to a cobra 29. I do like that idea of it and put the light behind the meter.

 

[AudioShockwav]

The TRC 448 had a modulation light.
I remember switching the lamps behind the meter.
If you can dig up the schematic and see were they pull it off.....

73
Jeff

 

[nomadradio]

Looks like the keying circuit in a Texas Star, but with a bulb and resistor in place of a relay coil.

73