Hello Necks

I doubt this will be of huge interest to many of you, But i thought id share anyways!

I have been using LTSPICE for a few years and whilst it is very helpful in many ways? It sometimes takes a bit of disorder to get it running

As with most simulation programs, It is assumed that every component is perfect! As we all know this is not true in real world situations.

I have found with most oscillators wont start up if the DC Voltage is set to instant! It needs to gradually rise from zero!

The following images i will post are of the NRG VFO had another problem at start up! If you are not familiar with this type of oscillator? A symmetrical signal is needed for the best response?

However, This is SPICE!! Symmetry was TOO accurate which in turn cancelled all response!

You may notice in the images that one capacitor is a bit wonky!

Another fan of LtSpice here!
What it bothers me of this program is the library, that is Linear Tech and Analog Devices centered only on their products, and it is lacking a lot on common diodes, transistors, etc, then you have to go and install the models manually.

Anyway, interesting simulations Sinus!
In the schematic I don't see the spice directive of the coupling coefficient between the oscillator coils (it should be like K L1 L2..... 1) without this you are telling the simulator that each coil is magnetically isolated from each other.
Would be nice to play arpund with this.

why i have never get an legit old 2n2218 or 19a to work as an amplifier , when it is Ft go to 250mhz and when he can put out as 0.8 or 800 mw as described in datasheet , i tried many time replacing a 2n3866 or 2n4427 with 2n2219 never get it work , any advice

radium98 wrote: ↑Sun Apr 18, 2021 7:19 pm why i have never get an legit old 2n2218 or 19a to work as an amplifier , when it is Ft go to 250mhz and when he can put out as 0.8 or 800 mw as described in datasheet , i tried many time replacing a 2n3866 or 2n4427 with 2n2219 never get it work , any advice

Maybe make a new thread about it.

Krakatoa wrote: ↑Sun Apr 18, 2021 8:18 am Another fan of LtSpice here!
What it bothers me of this program is the library, that is Linear Tech and Analog Devices centered only on their products, and it is lacking a lot on common diodes, transistors, etc, then you have to go and install the models manually.

Anyway, interesting simulations Sinus!
In the schematic I don't see the spice directive of the coupling coefficient between the oscillator coils (it should be like K L1 L2..... 1) without this you are telling the simulator that each coil is magnetically isolated from each other.
Would be nice to play arpund with this.

I have to agree Krakatoa, the Library is very limited! Most of the components never even heard of before!
If it wasnt for the fact that it is widely known and easy to get hold of Spice models? It would be useless!

Ah yes ive used that coupling Spice directive previously on my band 1 receiver experiments (Image below) As far as i know? The oscillator coils on the NRG VFO are not coupled?

radium98 wrote: ↑Sun Apr 18, 2021 7:19 pm why i have never get an legit old 2n2218 or 19a to work as an amplifier , when it is Ft go to 250mhz and when he can put out as 0.8 or 800 mw as described in datasheet , i tried many time replacing a 2n3866 or 2n4427 with 2n2219 never get it work , any advice

I do like the 2n2219 and have used it many times

As far as i know? It is very similar to the the 2N4427 but not identical ofcourse!

That 800mW figure is an absolute maximum rating! I would say that 400mW is the best you will get?

I believe Multicomp are still manufacturing them? Farnell stock a substantial range of Multicomp products, So they must be pretty decent quality?

One thing i would like to add about LTSPICE is that i have managed to grasp only a small portion of its capabilities!

It is a very powerful tool considering it is free!

thank you for the valuable infos as always .