4) First Test I hooked up a current meter in series with the power supply and started ...

2025-01-19 21:21:19

4) First Test

I hooked up a current meter in series with the power supply and started to tweak the gate bias. The board draws 22 mA with the bias completely off. I turned the potentiometer until the current reached 42 mA, which should mean that each FET get about 10 mA of current.

I tested with the PA connected to the 13.2 V power supply and a few different power levels:

* 0.08 W in, 0.51 W out, (current not recorded)
* 0.16 W in, 4.07 W out, 2.3 A
* 0.26 W in, 11.0 W out, 3.6 A
* 0.51 W in, 28.8 W out, 5.8 A

The harmonic content was pretty terrible, as expected. I haven't added any low pass filter on the output yet. I've also heard that lower gate bias means more crossover distortion and non-linearity, so that makes sense.

Author Public Key

npub133kx3vtsccvrn4uxjn85wacm45uqglre8qz7z7tr86p6lhy0whsqmhfazx

Show more details

Published at

2025-01-19 21:21:19

Kind type

1 Short Text Note

Event JSON

{ "id": "b403e50e2bb2108bde4d2765e84cd965ac98954177c548bd054664cc85a6721f", "pubkey": "8c6c68b170c61839d78694cf47771bad38047c793805e179633e83afdc8f75e0", "created_at": 1737321679, "kind": 1, "tags": [ [ "p", "8c6c68b170c61839d78694cf47771bad38047c793805e179633e83afdc8f75e0" ], [ "imeta", "url https://media.tilde.zone/media_attachments/files/113/857/091/263/667/674/original/0399f7ef4a5e7898.jpeg", "m image/jpeg" ], [ "proxy", "https://tilde.zone/@raek/113857113562242491", "web" ], [ "e", "b055b6a36eab8d7955c5d8ea676533523c2bbdc3c463f72f3b4797cf9d7c625f", "", "root", "8c6c68b170c61839d78694cf47771bad38047c793805e179633e83afdc8f75e0" ], [ "e", "406e74cbb006d8c2ac8ea513ac172d0c8ccc4570f41c7025da6286c23094d1c9", "", "reply", "8c6c68b170c61839d78694cf47771bad38047c793805e179633e83afdc8f75e0" ], [ "proxy", "https://tilde.zone/users/raek/statuses/113857113562242491", "activitypub" ], [ "L", "pink.momostr" ], [ "l", "pink.momostr.activitypub:https://tilde.zone/users/raek/statuses/113857113562242491", "pink.momostr" ], [ "-" ] ], "content": "4) First Test\n\nI hooked up a current meter in series with the power supply and started to tweak the gate bias. The board draws 22 mA with the bias completely off. I turned the potentiometer until the current reached 42 mA, which should mean that each FET get about 10 mA of current.\n\nI tested with the PA connected to the 13.2 V power supply and a few different power levels:\n\n* 0.08 W in, 0.51 W out, (current not recorded)\n* 0.16 W in, 4.07 W out, 2.3 A\n* 0.26 W in, 11.0 W out, 3.6 A\n* 0.51 W in, 28.8 W out, 5.8 A\n\nThe harmonic content was pretty terrible, as expected. I haven't added any low pass filter on the output yet. I've also heard that lower gate bias means more crossover distortion and non-linearity, so that makes sense.\nhttps://media.tilde.zone/media_attachments/files/113/857/091/263/667/674/original/0399f7ef4a5e7898.jpeg\n", "sig": "a5fc99522ef46e54cdbb1fb6ab34d879323b825bb57916cf011e619c7eac2d5e4542ffda62e869350d01cc30aa1562d2a9c848089c8f26fed745caef243c33f4" }

Rasmus SA5RJS on Nostr: 4) First Test I hooked up a current meter in series with the power supply and started ...