So question is now, why have I as others gotten less than satisfactory results. Is it in our bias voltage settings?
Did you simply drop them in place of the 13n10's and no need of other component swaps?
Only asking to see where I'm coming short
One thing I just learned was that the input and output capacitances of these two parts is far different than I thought and in the opposite direction. For the 13N10 the Ciss was 567pf and Coss was 558pf. The ERF2030+ came in at a much higher Ciss of 1422pf and a Coss of 1270pf. That is enough to make a difference in the tuning of circuits and confuses me because no changes were made in the PA stage other than the transistors.
No bending of coils and no changing of any bias gate voltage. The only thing I can think of now that would be making the ERF2030+ work better in the Stryker SR-94HPC is that the transistor must have a faster rise and fall time where the 13N10 is at its limits.
The current reduction has made a noticeable difference in how cool the TIP31 series pass modulator runs too. The cast aluminum housing takes much longer to heat up and never gets as hot as it did. If you're concerned with how hot this radio normally runs when you get long winded, don't bother to change the modulator transistor, change both finals to the ERF2030+.
This radio seems to lack a tuned matching circuit between the driver and final stage like most CB's and looks capacitively coupled. That may explain why it handled the change in higher input capacitance over the stock finals. It doesn't explain why with no output impedance adjustment I saw and increase in power and a reduction in current, other than perhaps the original match was off.
I would experiment more with the output match if I had a schematic. I don't want to get into a situation where I can't identify output matching from things like 54 MHz. traps and the radio is working well so I think I'll stop fixing it before I break it again.
This radio may not even use any DC voltage on the gates. I didn't measure it but they may just be driving the finals with enough power to run them with zero bias. It did use one driver the same size as each final and that's a lot of drive capability. Think of your typical "3 pill".
The theory of zero bias being used here eliminates the pesky variable of riding the gate threshold voltage perfectly to maintain the gain required to produce rated power output. It's not so fussy if you have enough drive to eliminate the need of DC to turn the transistor on. Would be nice if they started publishing some idling current specifications for various classes of bias on these parts...
Then we would know right away if lack of power output was related to bias problems or matching problems on the input or output. Sad to say, Palomar can't even seem to provide any important specs like the gate threshold voltage for comparison so each parameter has to be tested on your own to find out as needed.
In most cases, the higher output capacitance of the ERF2030+ should require changes in the output matching such as a reduction in the value of any external source capacitor and bending of the next coil.
