07-06-2024, 01:02 PM
Neat, thanks for the video. I wonder how they justified the cost of two meter movements?
I want a PNP valve!
Philips PM2505 electronic meter
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07-06-2024, 01:02 PM
Neat, thanks for the video. I wonder how they justified the cost of two meter movements?
I want a PNP valve!
07-06-2024, 02:36 PM
(This post was last modified: 07-06-2024, 02:47 PM by Mike Watterson.)
(06-06-2024, 05:21 PM)djrm Wrote: The meter is averaging only on AC unfortunately but has a bandwidth up to around 30 kHz.Likely due to the op-amps. I have an old VVM. It does Ohms too. But I was surprised. Though the scale calibration is only good to a few MHz it "works" to UHF! All valves, an EB91 for AC and an ECC82 amp in mine, though those are really the same as the listed 6AL5 and 12AU7. Tech TE-65 https://bama.edebris.com/manuals/tech/te65 Though Mains based it has a D cell in it! Have to take out 6 screws to replace it. It seems to be used for Ohms. https://www.radiomuseum.org/r/tech_rmsv_...65te6.html The manual writes of using a specific probe for over 60 MHz. I used a scope probe. I've also used it with a T piece and 50 Termination. Technical data: Internal resistance is 11MΩ on all ranges (Cheap DVMs are 1M Ohm and better ones are 20 M Ohm) DC voltage measuring ranges: 1.5/5/15/50/150/500/1500V AC voltage measuring ranges Veff: 1.5/5/15/50/150/500/1500V Vss: 1.4/4/14/40/140/400/1400/4000V Resistance measuring ranges: 10/100/1k/10k/1M/10MΩ dB: -10 to +65dB (0dB=1mW at 600Ω) Normal accessories DC voltage test probe 2 measuring leads 1 monocell 1.5V 1 operating manual Special accessories HV test probe 30kV (28.50 DM) HF probe 250MHz (26 DM) Also sold in Germany as Conrad brand and as an Eico kit! http://www.radioboatanchorblog.com/blog/...estoration Better manuals http://bama.edebris.com/manuals/eico/232(3)/
07-06-2024, 02:39 PM
I have a meter I bought in latter part of 1960s that died, but the movement is still good. I'd be tempted to drive it with something like the Phillips circuit though it would need a new resistance scale.
07-06-2024, 02:41 PM
(07-06-2024, 01:02 PM)PerdioPal Wrote: Neat, thanks for the video. I wonder how they justified the cost of two meter movements? Likely the polarity one was very cheap. It can't have been a cheap meter.
07-06-2024, 02:47 PM
(07-06-2024, 02:41 PM)Mike Watterson Wrote:(07-06-2024, 01:02 PM)PerdioPal Wrote: Neat, thanks for the video. I wonder how they justified the cost of two meter movements? A couple of sensitive leds could serve the same purpose today perhaps. (07-06-2024, 02:39 PM)Mike Watterson Wrote: I have a meter I bought in latter part of 1960s that died, but the movement is still good. I'd be tempted to drive it with something like the Phillips circuit though it would need a new resistance scale. Whilst looking for information on the Philips IC used I read a suggestion that it could be replace by the discrete design used in the previous version of this meter if you wanted to duplicate all the functions 'as-is' (I take it that the schematic for the previous version is available, but I haven't looked myself)
07-06-2024, 03:14 PM
(07-06-2024, 02:47 PM)djrm Wrote: A couple of sensitive leds could serve the same purpose today perhaps.Any LED is a minimum of 1.2V, so two leds and an op-amp. AC would light both. AC with a DC offset could light one brighter? Very low frequency AC would flicker the LEDs. If I was re-using my old meter I'd maybe use really fast op-amps to have a few MHz and it would really measure peak, so DC scale would be peak and another scale would be AC RMS assuming a clean sinewave. For addition amusement add 300V approx via flash circuit from a single use camera via maybe several M Ohm to measure uA leakage or PIV or VCEBo etc. |
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