Function Generator Help

[Frosty_47]

Good day,

Please help me choose between these two function generators:

B&K Precision 4005DDS
B&K Precision 4011A

They are almost identical in price however the DDS looks more modest but it's overall linearity and stability that concerns me most. What is your take on this?

 

[JimB]

Depends on how you want to use it.

On the 4011A, the frquency is set by two tuning controls, coarse and fine.

On the 4005DDS, the frequency is set by entering the value on the keyboard.

So, if you just want an accurate fixed frequency, go for the 4005DDS,
but if you want to adjust the frequency over some range as if you are searching for a resonance peak or dip, then go with the 4011A.

JimB

 

[duffy]

I have the 4011A sitting on my bench. Like everything else I ever purchased from "BK Precision", it was JUNK.

The "Duty Cycle" adjust barely moves from 20% to 80% (same for the 4005DDS). In other words, you can't go down to 0% (full off) or up to 100% (full on) - not even close! Didn't the idiots who built these realize that one of the main uses is working with PWM, and you might possibly want a narrower duty cycle than TWENTY PERCENT?!

On top of that, the frequency drifts as you change the duty cycle.

Also, the "gate" function (how fast the display updates) is aggravatingly slow in the low ranges. It's TEN-FREAKING-SECONDS between each display update on the lowest range. So you turn the knob... and wait. And wait. And wait. Finally the display updates. But it's wrong - you have to wait for ANOTHER update because you were still turning the knob during the first one. So you wait...

Reason for the slow gate is they count cycles per second on the low range instead of seconds per cycle (and taking the reciprocal). The 4011A doesn't have even one single crummy little fifty-cent processor in it, anywhere. This one is 1970's-era logic-chip junk, a 40 year old design still being produced and sold for hundreds of $$$ by a company that is an insult to the word "Precision".

 

[ghostman11]

I have the 4011A sitting on my bench. Like everything else I ever purchased from "BK Precision", it was JUNK.

The "Duty Cycle" adjust barely moves from 20% to 80% (same for the 4005DDS). In other words, you can't go down to 0% (full off) or up to 100% (full on) - not even close! Didn't the idiots who built these realize that one of the main uses is working with PWM, and you might possibly want a narrower duty cycle than TWENTY PERCENT?!

On top of that, the frequency drifts as you change the duty cycle.

Also, the "gate" function (how fast the display updates) is aggravatingly slow in the low ranges. It's TEN-FREAKING-SECONDS between each display update on the lowest range. So you turn the knob... and wait. And wait. And wait. Finally the display updates. But it's wrong - you have to wait for ANOTHER update because you were still turning the knob during the first one. So you wait...

Reason for the slow gate is they count cycles per second on the low range instead of seconds per cycle (and taking the reciprocal). The 4011A doesn't have even one single crummy little fifty-cent processor in it, anywhere. This one is 1970's-era logic-chip junk, a 40 year old design still being produced and sold for hundreds of $$$ by a company that is an insult to the word "Precision".

so you wouldnt recomend it then???

 

[duffy]

Before I would recommend a BK function generator I would recommend strapping a potentiometer onto the rocker-arm of your lawnmower. It will be less trouble to adjust and respond quicker to a change in speed.

 

[Mr RB]

Before I would recommend a BK function generator I would recommend strapping a potentiometer onto the rocker-arm of your lawnmower.
...

That's how I do it!

And I have another on a little whippersnipper motor, that one is my RF signal gen.

 

[Frosty_47]

I have the 4011A sitting on my bench. Like everything else I ever purchased from "BK Precision", it was JUNK.

The "Duty Cycle" adjust barely moves from 20% to 80% (same for the 4005DDS). In other words, you can't go down to 0% (full off) or up to 100% (full on) - not even close! Didn't the idiots who built these realize that one of the main uses is working with PWM, and you might possibly want a narrower duty cycle than TWENTY PERCENT?!

On top of that, the frequency drifts as you change the duty cycle.

Also, the "gate" function (how fast the display updates) is aggravatingly slow in the low ranges. It's TEN-FREAKING-SECONDS between each display update on the lowest range. So you turn the knob... and wait. And wait. And wait. Finally the display updates. But it's wrong - you have to wait for ANOTHER update because you were still turning the knob during the first one. So you wait...

Reason for the slow gate is they count cycles per second on the low range instead of seconds per cycle (and taking the reciprocal). The 4011A doesn't have even one single crummy little fifty-cent processor in it, anywhere. This one is 1970's-era logic-chip junk, a 40 year old design still being produced and sold for hundreds of $$$ by a company that is an insult to the word "Precision".

Thanks a lot for your help. I am going to look elsewhere for a function generator