Achieving a bandwidth of 100MHz is easy. To get useful output at 500MHz inductive peaking of the collector loads of the input stage will be required. Correctly proportioned Bridged T-coils should work well. Cascoding the input stage may also help.
Bruce On Wednesday, January 27, 2016 08:38:15 PM Bruce Griffiths wrote: > Something like the attached schematic should suffice however an extra gain > stage would probably be necessary to achieve the 100mV sensitivity.NB Vcc = > 15V, Vee = -15V. Bruce > > > On Thursday, 28 January 2016 5:02 AM, paul swed <[email protected]> > wrote: > > > Some great comments and like all of you I like my 5370s and 5345s. Real > buttons no mouse. Must be a throw back to the dark ages. > Always knew about the fan issue on the 5370 and have added fans to my main > operating unit. > But it had not occurred to me that the way the front panel is laid out > there may be little actual airflow across those chips. Thats quite a > thought. > So for those with working units that may be a completely seperate thread. > How hot do they get? Then some solution for that. > Essentially fix it before it dies. > Then there is the question I posed. > Skipping all of the details like adjustable slicing polarity and such.. What > is the minimum to get a signal into the counter as a way to return it to > some usable service and certainly verify the bad frontend. Lets call this a > poor but useful answer. > From that point it returns to this discussion. > But a full new front panel. As Perry says most likely not. > I do have 2 X5345s that I am pretty sure I need to dive into the front end > on. My excuse other projects... > Regards > Paul > WB8TSL > > On Wed, Jan 27, 2016 at 7:46 AM, Bob Camp <[email protected]> wrote: > > Hi > > > > Ok, well let’s put some dimensions on it. > > > > Say that the new board for the counter costs $400 each. (and that’s > > probably low). How many are people likely to buy? > > > > If so how much would you pay for a working 5370? > > > > Bob > > > > > On Jan 26, 2016, at 11:08 PM, Perry Sandeen via time-nuts < > > > > [email protected]> wrote: > > > Hi, > > > Wrote: Since the front end chips are mixed signal ASIC’s, it will take > > > > more than a bit of time to replace them directly. Re-doing the entire > > front > > panel board is the most likely way to “fix”the problem. The question is - > > why do that at all? Just do a PC instrument that does the same thing as > > the > > counter with way less effort….. > > > > > Well, I have two reasons not to. > > > First I have about $1800 invested in my 3 5370’s including the new CPU > > > > boards and blowing that off is not in my budget. I’ll kludge the living > > daylights out of my units before blowing off my investment. > > > > > Second, I haven’t the slightest clue on how to do a PC instrument and I > > > > have to many other projects to finish to learn something new. > > > > > Also there was much discussion about A and B cooling in the past and it > > > > seems the only things some did to their units was the addition of fan(s) > > on > > the cooling fins. I had an external fan on a B I was running and the > > thing > > still was too hot. > > > > > IMNSHO, I believe the front end chip failure is aggravated by the high > > > > interior heat level. I’m committed to a number of other projects so it > > will be a while before I can work on mine. > > > > > I’ll either rip the whole PS out and put it on another chassis, try > > > > better 3 terminal regulators instead of the installed pass transistors, > > install switching regulator PS’s in place of the original PS, cut holes in > > the top lid and install 10 or 12 computer fans. Or a combination of the > > afore mentioned. > > > > > I don’t give a rat’s behind how it will look. I’m only interested in it > > > > working properly. I’ve spent 50 years in the electronics industry and I > > will find a way to skin this cat. I’ve done this to other equipment > > before. > > And when done I’ll tell the list how I did it. > > > > > Regards, > > > Perrier > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the > instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
