Are we still talking BIAS?
Find yourself a Datasheet and review some Key points.
On thing is not being mentioned here...how much current is needed to BIAS that part?
For a 2 Pill? The Datasheet says 150mA for the DUT Test Jig, 1-part only (in this posts' example) and also requires a given level of input power - too much power the BIAS can force the DUT ON and STAY ON as if it was a SWITCH - don't worry, it will blow possibly take some traces and their components with it in the process when you've gone too far..
The thing to remember in all of this advice, when you run SSB or AM - if you have a BIAS drive into this mess. Your Pills don't need as much power as those whom use Class C biasing (Refer to the 10-ohm resistor commentary...)
So if you're asking about THE AMOUNT you need for a part, do what Sheepherder's do when it comes of counting inventory - Count all the LEG's and Divide By 4... that result is then MULTIPLIED by the BIAS current in mA. (See Above) You also can take that LEG result and divide by the number of pills and DERATE to 70% (e.g. - Multiply pill count by 0.70 your 70%) to handle losses in network ohmic and Mismatch losses within your feeder design, this "value" is your wattage - your Window is BIAS floor onto the Wattage for your input power levels.
- If you pair Pills, think 300-325mA BIAS max
- Each Pair needs to be fed SEPARATELY and EVENLY from your feeder.
- Current limiting?
- Might want to use a #194 bulb to provide a working indication and buffer so as you OVERDRIVE that amp in error you lose your Clean signal - heat up excessively (power dissipation) and SATURATION
- - the BIAS DC values will skyrocket (See cautions) so you'll need to limit the BIAS values from dumping into the part until it blows, Pull back your BIAS - how? That bulb, remember the Choke and Resistor combo?
- There's' a good reason for it - you don't want your BAIS climbing into and adding power into the signal you're trying to amplify, you just want the Transistor just biased (Barely) off to allow the input RF to trigger ok? Don't throw the BABY INTO the Bathwater without checking it's temperature first, both the Childs' and the Water...
- This means the BIAS current may STARVE, so what? It's there to BIAS the part on, not to LATCH UP and turn on lights. The BIAS will "starve" but the part reduces to Class C (A Fallback - due to Current Limiting) Keep the BIAS stable - don't let it, your foot and all the rest of the Kitchen Climb into the INPUT at the same time.
- IF you Get Distortion, Grab the Datasheet - learn right along with me too...
So if by this example - you have a 2-pill for SSB, you need 150mA per part, so currentwise, you'll need a delivery feeder system set up to handle 300mA AT LEAST.
Each Pill pair, needs it's own feeder from the BIAS source (your #194 LAMP) if you run standard 12V ignition...
