You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

I really prefer an envelope detector.

All you get is a DC voltage from the carrier and the audio envelope riding on it. Just about any 'scope will display this just fine, whatever the rated bandwidth may be.

Best advantage for me is that I can trigger the 'scope on the audio envelope this way. A 100 MHz 'scope displaying your RF signal is probaby quite capable of triggering to the 27 MHz carrier wave. But your audio is what we care about. Persuading a 'scope to give you stable trigger from the audio envelope alone is a bit tricky.

The venerable old Heathkit "cantenna" dummy load has one of these built in, feeding a phono jack. You have to make the RF-bypass ceramic disc cap smaller, and put a 10k resistor across the output to get a good audio waveform.

Gotta build one to go inline with the coax.

Oh, wait a minute... I already did.

Never have plugged it into a 'scope. Oughta do that.

73

<blockquote data-quote="nomadradio" data-source="post: 626144" data-attributes="member: 22">I really prefer an envelope detector.All you get is a DC voltage from the carrier and the audio envelope riding on it. Just about any &#039;scope will display this just fine, whatever the rated bandwidth may be.Best advantage for me is that I can trigger the &#039;scope on the audio envelope this way. A 100 MHz &#039;scope displaying your RF signal is probaby quite capable of triggering to the 27 MHz carrier wave. But your audio is what we care about. Persuading a &#039;scope to give you stable trigger from the audio envelope alone is a bit tricky.The venerable old Heathkit &quot;cantenna&quot; dummy load has one of these built in, feeding a phono jack. You have to make the RF-bypass ceramic disc cap smaller, and put a 10k resistor across the output to get a good audio waveform.Gotta build one to go inline with the coax.Oh, wait a minute... I already did. <img src="https://imageshack.com/a/img923/5932/NMAOVG.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />Never have plugged it into a &#039;scope. Oughta do that. 73</blockquote>

[QUOTE="nomadradio, post: 626144, member: 22"] I really prefer an envelope detector. All you get is a DC voltage from the carrier and the audio envelope riding on it. Just about any 'scope will display this just fine, whatever the rated bandwidth may be. Best advantage for me is that I can trigger the 'scope on the audio envelope this way. A 100 MHz 'scope displaying your RF signal is probaby quite capable of triggering to the 27 MHz carrier wave. But your audio is what we care about. Persuading a 'scope to give you stable trigger from the audio envelope alone is a bit tricky. The venerable old Heathkit "cantenna" dummy load has one of these built in, feeding a phono jack. You have to make the RF-bypass ceramic disc cap smaller, and put a 10k resistor across the output to get a good audio waveform. Gotta build one to go inline with the coax. Oh, wait a minute... I already did. [img]https://imageshack.com/a/img923/5932/NMAOVG.jpg[/img] Never have plugged it into a 'scope. Oughta do that. 73 [/QUOTE]

Top Bottom