[Lowfer] Lowfer Final Transistors-Switching Time

[Andy - KU4XR]

In the " just for the fun of mentioning it " catagory. I have been
looking over the datasheets for the 2222/2907 ; 6602/6652 ; 4401/4403
pairs. First; the 2N2222/2N2907 series will perform fine. You can get
about 150 MilliAmps more Collector Current capability by using the
2N2222A & 2N2907A series. These are the TO-18 metal cases. They will
handle 800 mAmps. The MPS 6602/6652 series will handle 1 amp on the
collector. Without going into all the numbers details which you can
look for yourself if you desire, there is one thing that makes the
2N4401/2N4403 pair a good choice also,,,,,,  The switching times !!
I have used this pair, and they will give the MPS 6602/6652 a good
run for the money. And they are easily obtainable, very cheaply too.
I tried all the NPN's , and PNP's until I found the pair that 
produced the most output for 1 watt input, and ended up running the 
same RF current that the 6602/6652 pair would do. I can't measure 
this, but according to the datasheets, the 6602/6652 both have an
ON time of 55 Nanoseconds, and an OFF time of 300 Nanoseconds.
The 4401/4403 pair have an ON time of 35 Nanoseconds, and an OFF time
of 250 Nanoseconds. So, going by the datasheet information only; the
4401/4403 pair will switch slightly faster than the 6602/6652 pair.
That's on paper, and we all know from experience that in the material
world; devices don't always perform according to the spec sheets, but
usually come very close with quality components. In my actual use, I
found the 4401/4403 pair would outperform the 2222/2907 pair, and run
neck to neck with the 6602/6652 pair in my beacon transmitter here.

FWIW; that is my experience. I hope someone finds the info interesting.

73 all :::


Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )

*** Temporarily OFF, while constructing a new antenna ***

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