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DC502 Option-7 re-visit

NigelP
 

I posted this a couple of years ago but have so far drawn a blank. I'm trying to acquire an option-7 PCB to fit DC502 (and possibly others). It provides a stop/start function for frequency measurement in conjunction with a tracking generator and spectrum analyser. My setup is TR502 + 7L14 + 7603. It's not particularly complicated (a half-dozen TTL gate chips or so) and I have the schematic and could possibly re-create a bread-board version but would much rather either get an original or copy a PCB design. Unfortunately the info available for Option-7 does not show the complete PCB tracking (only one side) and this initially lead me to believe the PCB would be really simple until I had cause to evaluate it more closely and found that, as a minimum, there were no power busses running around!

Last time I did have a respondent who was working on a PCB but unfortunately it seems to have lead to a dead-end.

 

Hi Nigel,
If I am not mistaken you are referring to a DC508 which is capable of counting to 1.3GHz, not a DC 502 which is a 110MHz counter.

If I am not mistaken the Option 7 PCB you are referring to is already in every DC508. Half of it is not populated if the DC508 does not have the Option 7. Other changes are also involved if the DC508 has Option 7 such as the higher precision crystal.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of NigelP
Sent: Wednesday, November 20, 2019 4:08 AM
To: TekScopes@groups.io
Subject: [TekScopes] DC502 Option-7 re-visit

I posted this a couple of years ago but have so far drawn a blank. I'm trying to acquire an option-7 PCB to fit DC502 (and possibly others). It provides a stop/start function for frequency measurement in conjunction with a tracking generator and spectrum analyser. My setup is TR502 + 7L14 + 7603. It's not particularly complicated (a half-dozen TTL gate chips or so) and I have the schematic and could possibly re-create a bread-board version but would much rather either get an original or copy a PCB design. Unfortunately the info available for Option-7 does not show the complete PCB tracking (only one side) and this initially lead me to believe the PCB would be really simple until I had cause to evaluate it more closely and found that, as a minimum, there were no power busses running around!

Last time I did have a respondent who was working on a PCB but unfortunately it seems to have lead to a dead-end.





--
Dennis Tillman W7PF
TekScopes Moderator

NigelP
 

No, in fact DC502, not 508. The DC502 is 550MHz via the x10 pre-scaler and works fine up to (and beyond) the specified frequency. All the necessary Tek info clearly state the DC502 modifications. With a very slow sweep and/or small BW setting it's useable but this is clearly not ideal.

Regards

Nigel G8AYM

scskits
 

Nigel:

I have made a PCB for the DC502 option 7, but have not acquired a spectrum analyzer or tracking generator to try it with. Made per the Tektronix schematic with similar 0.1 pin spacing connectors in the same locations. Keep in mind that there are modifications necessary to the DC502 in order to use the option 7.

ed

 

Hi Nigel,
I love it when I learn something new. I had no idea the DC502 had an X10
pre-scaler. Apparently I never owned a DC502. That is the most likely
explanation for why I wasn't aware of its 550MHz capability.

I suspect the pre-scaler is identical, or at least similar, to the 525MHz
front end of the 7D14 Frequency Counter for the 7000 Scopes. It uses a
Johnson Counter, also known as a ring counter.

I am, at the moment, trying to figure out why my DC508A with Option 7 does
not work correctly with my TR502 Tracking Generator. They are both in a
TM503 which has the necessary interconnecting wiring. I wired up everything
myself and that may have something to do with it.

The advantage of the DC508A is its 1.3GHz capability. But that still falls
short of the 1.8GHz capability of the 7L14 Spectrum Analyzer. I find that
really annoying. I'm sure the 550MHz limit of the DC502 is even more
annoying to you.

If possible keep me posted on your progress. When you finally get it working
I would love to see a photograph.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of NigelP
Sent: Thursday, November 21, 2019 3:07 AM
Subject: Re: [TekScopes] DC502 Option-7 re-visit

No, in fact DC502, not 508. The DC502 is 550MHz via the x10 pre-scaler and
works fine up to (and beyond) the specified frequency. All the necessary Tek
info clearly state the DC502 modifications. With a very slow sweep and/or
small BW setting it's useable but this is clearly not ideal.

Regards
Nigel G8AYM




--
Dennis Tillman W7PF
TekScopes Moderator

NigelP
 

Ed, I would be happy to be a guinea pig for this if you are reasonably comfortable that there are no serious errors in the layout (ie like blowing up DC502s !!!..... only joking).

I'm aware of the need for mods to both 502 and TM500 for this to work.

Let me know if you want to propose something.

Dennis, yes I would like a 508A but very unlikely to find anything this side of the pond and it gets unbelievably expensive to ship stuff from the USA to the UK (assuming you want it to arrive in one piece). I have purchased a few bits from the US but have to bite the bullet on shipping costs.

In fact it is not so much the actual US shipping charges, but once it gets into the UK the customs tax AND the ludicrous charges made by the Post Office just to handle the customs fee make it silly. One item I recently bought cost me twice the original sale price! I've had one or two things "slip through the net" but larger items are unlikely to get through un-noticed.

Regards

Nigel G8AYM