Do you have any directions for the 6666 on how to check the bias? Test points for meter? Cant seem to find anything on the Anytone 6666 as far as directions to set bias. Would like to see where it sits with just the drop in. And set it if needed. Also what do you recommend for settings? Thanks
You can try here...
https://www.worldwidedx.com/threads/to-anyone-who-has-adjusted-the-bias-on-an-anytone-6666.258304/
The process above is for; WHEN YOU DO NOT HAVE ANY MEANS TO READ CURRENT going to the MOSFET Finals...
You have to remove all the jumpers in the TX section - described in the link provided...
BUT, you don't have jumpers for the Finals - the Finals are "tied together" to the same source voltage back at the potentionmeter
- - but no way to know how to set the "drive voltage threshold" to make the current start to flow.
It is different for a MOSFET - for you have to still monitor current - and if you don't and just "set a voltage" - and hope for the best - well then Hope for the best because you may have set the threshold too high or not enough and you'll have operational problems and potential failures either way...
Set up your DVM to read Amps - 2A for now and pull all the jumpers in the TX section so you are not able to send any RF power into the TX amp strip...
You are going to measure a current draw at the power supply feed - as you found out you don't have "a jumper" at the Finals pair - just a pot.
Put on a dummy load at the SO-239 - 50 ohms 10W minimum
Put the DVM in line with the Positive side POWER leads, in line - series to read intake current = into the radio
- - because again voltages are making the amp section DEPENDENT on current flow - you can;t have one without the other...
Set up radio in SSB mode - Power up the radio - watch the meter for amperage draw - if you've done your homework, and read the steps at the link and turned the pot down and did the setup right - you'll see a brief surge in current then it idles to about 50mA or less - once that reading has stabilized - TX the radio.
The idle current will rise to a point then stabilize, then you adjust the pot to the POINT WHERE CURRENT RISES ABOVE the TX IDLE CURRENT "average" or TX ON level by 55mA.
- It's a difference in reading from TX idle no audio
- If you're at 0.125A or 125mA on TX - then you're looking for 0.180A or 180mA for that magic 55 number.
- Turn the pot up until you achieve that number 55 in mA RISE from TX idle.(no audio)
- Do not go above that - it can rise too quickly and make one if not both, finals blow from switching on and latching - even at DC.
This "rise" is important to know, for too much voltage applied will make the current rise too quickly and possibly blow the finals - if you "just set votlage" and not monitor the current - don't say we didn't warn you...read above...and at the link.
You are merely looking at you ammeter setting at a point in line that simply lets you see not just the radio power intake, but at idle power consumption...
- - it's idling at one level, you adjust the pot by reading the meter for that magic 55mA rise from idle draw.
Once set, you can then measure the Driver mA draw like you use a typical ammeter for, one lead to one pin of that header, the other lead to the opposite pin and in TX mode - set Driver bias current.
Do the same for the Pre-Driver too.
If that's too much to handle...remember this;
The only difference is the meter is at the power supply feed for the Final Drive current check - you can even stay in line at the power supply feed and do this step without having to mess with the pin on header to lead on DVM - you can set it back at the DVM per stage watching the meter at the power supply feed. Each stage consumes a set amount of current at it's proper idle in TX mode - you don't have to make it any harder than it already is.
Again
read the link!