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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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19th Oct 2018, 5:50 pm | #1 |
Pentode
Join Date: Oct 2005
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 200
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Pye VC290/24 voltage converter
Hi All,
I have a couple of these units, which I believe to be 24v to 12v converters, possibly of Westminster vintage. I was surprised to discover that the unit contains an inverter type converter, not just a dropping resistor as I had expected. I haven't been able to track down any manual info on these units, and hope that somebody can tell me how much current they will deliver at 12v - if they are Westminster accessories they should be good for 5A or so I would think.
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Peter G8BBZ |
19th Oct 2018, 6:11 pm | #2 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: Pye VC290/24 voltage converter
Actually they are later - mid 1980s for M290 and MX290 series.
Yes they are a switcher. I would expect 5A perhaps some more. They will have current limit or shutdown, try it out |
20th Oct 2018, 8:04 pm | #3 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,005
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Re: Pye VC290/24 voltage converter
I have memories of these fitted in cattle-haulage trucks in the very-early-90s, powering VHF high-band MX290s.
One truck regulary came back from continental trips with the radio not-working and the 24-to-12V brick dead. Turned out that the driver in question had worked out how to disconnect the MX290 and hook up his 12V-powered portable-TV to the output of the dropper. It was a 17-inch colour-portable so expected quite a few amps when running off 12V; more than the Pye dropper-brick could reliably provide for hours at a time. |
21st Oct 2018, 11:26 am | #4 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: Pye VC290/24 voltage converter
Interesting tale, so no current limit and possibly no over temperature protection is suggested. That is disappointing.
I have never taken much interest in them (no 24V environments) but I will be looking for a circuit too now! Last edited by Jon_G4MDC; 21st Oct 2018 at 11:39 am. |
23rd Oct 2018, 10:07 pm | #5 |
Pentode
Join Date: Oct 2005
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 200
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Re: Pye VC290/24 voltage converter
Thanks for the replies.
The units do seem to be very simple - a pair of TO-3 power transistors as oscillator,a ferroxcube transformer and a couple of meaty rectifier diodes. No stabilisation, no current limit. Nice story about the cattle trucks. If a circuit does come to light I would welcome a copy.
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Peter G8BBZ |
24th Oct 2018, 10:32 am | #6 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: Pye VC290/24 voltage converter
That is surprising Peter, next will you say the TO3s are marked NKT404!?
(Re-hash of Pye Cambridge Inverter) |