[time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort

Alexander Pummer alexpcs at ieee.org
Wed Jan 27 21:27:21 EST 2016


there are amplifiers with multiple GHz gain bandwidth product, 
[http://electronicdesign.com/analog/18-27-ghz-chip-set-operates-little-18-v] 
also the high speed  ECL line receivers have available gain 
[http://www.ti.com/lit/ds/symlink/sn65lvds4.pdf]
73
KJ6UHN
Alex

On 1/27/2016 2:22 PM, Bruce Griffiths wrote:
> 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 <paulswedb at gmail.com>
>> 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 <kb8tq at n1k.org> 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 <
>>> time-nuts at febo.com> 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
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