DSE Bargain CRO - Page 2

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Re: DSE Bargain CRO


Was that the EA 3inch CRO?  I built one of those - but some bastard broke into
my workshop and stole it

David

Phil Allison wrote:

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Re: DSE Bargain CRO



"quietguy"

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** The mag was still called  Radio TV and Hobbies (RTV&H) in May 1966 when
the CRO design I built was published.

It used the Philips DG7-32  3 inch CRT,  2 x 6GH8s for vertical, 2 x 6BL8s
for horizontal and a 12AT7 for the synch. The PSU used EM408 silicon diodes
and the tube had a full Mu-metal shield - an essential item missing from
most budget CROs.  Vertical bandwidth was 2 MHz and all ranges were
calibrated in 1-2-5 steps.


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**  Probably thought it was a mini TV set.



..........  Phil




Re: DSE Bargain CRO



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If it's "essential", why then are you recommending the DSE CRO. Does it
really have a Mu metal shield?

MrT.



Re: DSE Bargain CRO



"Mr.T"
 "Phil Allison"

** The mag was still called  Radio TV and Hobbies (RTV&H) in May 1966 when
the CRO design I built was published.

It used the Philips DG7-32  3 inch CRT,  2 x 6GH8s for vertical, 2 x 6BL8s
for horizontal and a 12AT7 for the synch. The PSU used EM408 silicon diodes
and the tube had a full Mu-metal shield - an essential item missing from
most budget CROs.  Vertical bandwidth was 2 MHz and all ranges were
calibrated in 1-2-5 steps.


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**  A mu-metal shield is not essential for a CRT CRO to function  -  but it
an "essential item" for any respectable lab or workshop instrument.
Practically all older CROs ( pre 1980) and those priced over the $ 1500
level have one.

So far, I have not "recommended"  the DSE  budget CRO to anyone,  but  I
really doubt there is any new, CRT CRO at  near the price that has mu-metal
CRT shield.

BTW

For those who don't know, lack of a magnetic CRT shielding means the trace
is vulnerable to 50 /60 Hz displacement (seen as annoying shimmer or wobble)
by radiated fields from any AC supply transformer placed near the
instrument.  These fields are hardy attenuated by the steel casing of the
CRO and can affect the trace at up to 1 metre away.

This is not such a big problem with small, lightweight CROs ( like the DSE
one)  that can simply be moved from the source of AC hum field as need be.


........   Phil




Re: DSE Bargain CRO



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it
mu-metal
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wobble)
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Good reply Phil, and I certainly agree that the DSE CRO looks like being the
answer to many poor hobbyists prayers. It used to cost that much for a cheap
3 1/2 digit DMM.

MrT.



Re: DSE Bargain CRO



 "Phil Allison"
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**  My first DMM was a "Kaise " 6200,  bought from Radio Despatch service in
about 1981  -  price inc sales tax was  $87.00  equal to about a $220 in
today's value.

The DSE bargain  CRO  is cheaper than a  Fluke  70 series meter now.



..........   Phil






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