Jim, Thank you. When studying this, most optocoupler diagrams show 3 connections, VCC, OUT, GND/NEG. For amplifier keying there's only two wires, POS and NEG which need to be connected to key the amp. I wasn't sure how to connect in that manner (three connections). My drawing above just?connected the two wires from?the amp, energising the amp TR relay. How would I have used the three connections? What am I missing? Bob W4JFA
PS. BTW 2N2222 transistors can have different pinouts so always check these. Lots of reading about that on it online.
I used an opto-22? ?opto isolator.? You can get em in 5 vdc.....15 vdc...and 24 vdc? on the input side....... (and each of those 3 x different input vdc's is nominal...... IE:? u can go a LOT higher / lower).? ? And they only draw 10 ma on the input side.? ?Output side on any of them is either 60 vdc @ 3 amps? CCS...... or 250 vdc @ 1 amp CCS.? ? Switching time is 100 Usecs for operate, to turn em on.... and 750 Usecs to turn em off, for rls.? ?5 kv isolation between the input and output side.? Input and output sides are isolated via the laser between em...hence the term, opto isolator.??
That's as dead simple as it gets.? ?And NO mech, slow relays involved anywhere. We use em to key the coils of sped up vac relays.? The last thing we want is a 5-15 msec slow relay that in turn keys the coil of a sped up vac relay...which would defeat the initial purpose of the sped up vac relays.? ? Same opto isolator can also be used for cut off biasing on a triode amp. Our friends in VK land have that concept down to a fine artform.? ?The secondary of the opto just shunts the bias cut off resistor.? Again, dead simple.
Another option is to use a switch transistor.? $1.85 in the mouser catalog.? Switches in 3.6 u secs. They will handle a helluva lot of voltage and current...and are the fastest thing available.? Issue is...IF they ever failed shorted, the OCV ( open circuit voltage), or in my case the overvoltage used to speed up a vac relay, will then appear across the puny switch transistor typ used in most xcvrs...and kaboom, there goes the puny switch transistor in the xcvr.??
The opto-22 was used in several HB metal triode tube amps.? It was used in the 10 kw? 6m amp.....and it is also used in the 10 kw? 160-15m amp.? The opto keys the Jennings? RJ1A used for the input...and also another RJ1A for the cut off bias....and also 2 x Jennings RJ2B's (contacts in parallel)? for the 10 kw output side.?
Local eng buddy of mine used the same config on his YC-156 amp, except he used +170 vdc? to speed up the 26,5vdc coils.? ?The biggest cap he could install in parallel with the series drop resistor was just .5 uf.? ?That's called a ...."RC hotshot" circuit.? ?In his case, he's a hardcore? QSK CW op.? ?When tested individually on the bench, one of the new ( sped up with 170 vdc plus a .5 uf cap across the drop resistor)? RJ2B's would operate in 2.4 msecs.? The 2nd RJ2B would operate in 2.6 msecs.? ? The cap across the drop resistor will speed up the relays even more, BUT it also forms a? RC time constant on release.? For QSK CW use, that RC time constant has to be kept really low.? ?He could have used a lower overvoltage and a bigger cap across the drop resistor.? When T=0, the discharged cap presents essentially a dead short...and the max overvoltage appears on the coil of the vac relay.? ( you can easily measure that, with a fluke 87 DVM in 1 msec peak mode, tnx scott).? ?Once the cap is charged up, it's game over....since the cap will block DC current....and the now alternate path is through the drop resistor that the cap is in parallel with.??
When going back to RX, the charged up cap (which had the same vdc across it as the series drop resistor, since they are in parallel) now has to discharge through the drop resistor....and that takes time.? It takes a full 3 x RC time constants to discharge any cap? down to 5% of it's original max vdc.? ?For SSB use, ( or semi break in CW) a 5-10 msec? RC time constant is used? (IE: 15- 30 msecs for 3 x RC time constants).? ?For? QSK CW, you want a helluva lot faster than that.? ?Reason is, you want that cap fully discharged? between dots and dashes, so the enhanced speed up action of the vac relay can be maintained.?
On Alpha's? older desk top amps, they used? 36 vdc? and a drop resistor, and a cap across the drop resistor, to speed up the 26.5 vdc? RJ1A they used on the output side.? They ran QSK CW just fine.? ?But the RJ1A / Kilovac HC-1 / Gigavac G1H? are all stupid fast when operated at rated voltage.? ?That 8/6 msec operate time they quote is when the minimum pull in voltage is used.?
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Bob