Hello Fred. Perceptions are certainly important to consider as a design spec. That's why I choose to reply to your post. I hope you didn't really expect to post such negativity with out some kind of inquiry, or reaction to your post. You imply some very strong things that I feel are simply untrue, so I'd like to request some clarification of your post(s). I'm not sure your post is really all that clear to most people.
Last I recall the board LxW have not changed, so I don't understand what you mean by increased real estate.(18:38:56) fredcooke: 1) added extra switching regulator without removing others, simply to reduce heat into the others, but adding board realestate and adding switching noise, probably, from a design that is highly noise critical.
The SMP circuit has been prototyped and is being tested now under a variety of loads and conditions. If we can measure noise, then this circuit will not be used. However if the measured ripple is reasonable, then it will likely be included as an option. Last I recall the circuit that has been proto'ed has unacceptable ripple, but also hasn't really been looked at, so it's not complete yet. Could have a wrong part installed for all we know now. Is there a particular load condition you are concerned about? We can likely simulate that load to measure the noise replacing perception with measurable tangible results.
Last I recall, the plan is to include the SMT option, and TO220 option. So one can choose which one they want. The SMT can be an OVP IGBT or MOSFET and driven directly, with out modification. The TO220 is driven by the LM chip and requires jumper wires to use with OVP devices. If you use the LM data sheets recommended transistor, you can use the same old circuit, but you require thru hole which has assembly costs associated. So as far as I've seen, you can put in what you want. It would appear your concerned that a DIYer can put in devices you don't approve. I don't understand the concern. You appear to be concerned that it's offering to many options and to much flexibility.(18:40:30) fredcooke: 2) moving all fuel to220 devices to SMD devices, moving resistive p&h control to PWM (noisy) p&h control in the name of vibration resistance and meeting some arbitrary test standards mil spec or similar
About the mill spec, that's a physical thing, not an electrical thing. The push for an SMT option is to meet vibration and physical stress design specs. The thru hole leads can't sustain those stresses. If that transistor could be found in SMT, I'm sure that transistor would be used as SMT.
About P&H PWM, there isn't any backing software for such an option, so I don't know what the switching frequency is, and therefore don't know why the concern of RF/noise. If one uses an over sized OVP IGBT or MOSFET, then writes some code to PWM it, they might get some weird results. But for now, the SMT would be for HighZ applications, and would allow one to experiment with the potential of using it as LowZ, but that's a long ways off. It again implies your concerned we are planning to offer to much flexibility.
You seem to indicate you have a lack of understanding of thermodynamics. Testing that regulator circuit is fairly straight forward, predict the maximum load, put on that load, then toss it in an oven set for around 110F (43C) and watch the noise floor rise because the LDO's internal compensation kicks in. The linear as design now, has a limited scope, and an optional SMP will widen the scope of applications. If you don't want that option, don't use it. Again it appears your concerned with the flexibility.(18:41:05) fredcooke: 1 is silly because there is very little heat anyway, a better solution would be to ditch the fancy smd regulator and move it onto the heatsink bus as a to220 (with appropriate leg layout)
I ran out of time to finish my reply. Several of your above comments appear to be out of context to me, and I don't follow them. The design specs we have set forth on Puma certainly include perceptions, and negative comments will likely cause a reaction from those of use involved in the design. The goal is to make a quality product both in reality, and in perceptions.