DSE Bargain CRO

"quietguy"

** 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.

** Probably thought it was a mini TV set.

.......... Phil

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

MrT.

"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.

** 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

it

mu-metal

wobble)

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.

"Phil Allison"

** 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