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Old 27th Aug 2020, 10:19 pm   #1
Scotorvm
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Default Philips 830C here we go....

Set arrived, but the cover for the transformer on the speaker was smashed to Smithereens, somehow the seller decided to detach and bag on the outside of the radio??

So hours of superglue, headaches, VERY bright LED lamps, car body filler. It has been rebuilt, the 6 million dollar man springs to mind. Obviously this would never be the same, so going to spray a nice copper finish on this, as this set seems to be copper orientated..

Bakelite case now separated from the frame, steel frame to be cleaned and re-painted.

Original Waxers still in situ, looking forward to this restoration..

Looks like someone has done a half wave AC/DC MOD with a smoothing cap, would this set be OK with full wave rectification, I think so!!?

Only problem is The 'C' set info only seems available in Danish / German, does the 'A' version in English have the same schematics..

Cheers.

Lee
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Old 27th Aug 2020, 10:28 pm   #2
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Default Re: Philips 830C here we go....

Hi Lee ISTR that the C version was a DC model hence the Pseudo conversion.

So the circuit for the 830A won't be the same although I suspect the RF stages will be pretty much the same just using series heater valves.

I think you need to be a bit careful as rectifying the mains could result in the resultant DC being too high.

I think the circuit for the 830C is on the Radiomuseum site.

https://www.radiomuseum.org/r/philips_830c_1.html

Cheers

Mike T
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Old 27th Aug 2020, 11:00 pm   #3
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Default Re: Philips 830C here we go....

The 830A uses different valves and has a fairly standard transformer-FW rectifier PSU section. The circuits are quite similar but not identical- different biassing arrangements and a directly heated output valve in the 830A.

I don't think a bridge rectifier would suit the 830C- it would leave the HT- bouncing around at half mains.

The manufacturer's data are both available from http://www.nvhr.nl and the circuits can be compared regardless of language. Given the general similarity I would expect the alignment info in the English Trader Sheet data (up top) would be relevant taking into account any component reference differences from the Dutch circuits.
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Old 28th Aug 2020, 12:10 pm   #4
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by Cobaltblue View Post
Hi Lee ISTR that the C version was a DC model hence the Pseudo conversion.

So the circuit for the 830A won't be the same although I suspect the RF stages will be pretty much the same just using series heater valves.

I think you need to be a bit careful as rectifying the mains could result in the resultant DC being too high.

I think the circuit for the 830C is on the Radiomuseum site.

https://www.radiomuseum.org/r/philips_830c_1.html

Cheers

Mike T
Cheers Mike and thanks for the link, I have a bridge rectifier ordered, but I believe AC mains is around 340 peak to peak so assuming DC will be 320ish, was thinking about a transformer outputting 160vac then DC rectification should bring it up to 230DC

Thanks
Lee
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Old 28th Aug 2020, 12:14 pm   #5
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by Herald1360 View Post
The 830A uses different valves and has a fairly standard transformer-FW rectifier PSU section. The circuits are quite similar but not identical- different biassing arrangements and a directly heated output valve in the 830A.

I don't think a bridge rectifier would suit the 830C- it would leave the HT- bouncing around at half mains.

The manufacturer's data are both available from http://www.nvhr.nl and the circuits can be compared regardless of language. Given the general similarity I would expect the alignment info in the English Trader Sheet data (up top) would be relevant taking into account any component reference differences from the Dutch circuits.
Thanks Chris trying to find the best way to achieve stable 230vdc, not as easy as it sounds, no rush though I'll try a few different routes. Thanks for the link to the Netherlands, I have purchased the DVD from this site and can print the info for the 'A' version, will compare with the version for the 'C' set.

Cheers
Lee
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Old 28th Oct 2020, 10:03 pm   #6
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Default Re: Philips 830C here we go....

Have been working on a DC PSU for this radio for a few months on and off with assistance from someone who gave me a lot of help (hopefully this version won't disappoint) , a few attempts made, this is un-certified but seems pretty stable, power resistors not too hot. Possibly over engineered.

Mechanical cooling provided by a PC fan via pot to control speed. Supplied from a stripped down 12v charger.

Grill covers - Stainless Steel Woven Wire Mesh Rodent Proof Metal Mesh Sheet 1.94mm Hole - spray painted.

DT-200VA 220V - 110V Step Up & Step Down Voltage Transformer Converter UK to US 110V & 220V outlets, parts stripped and re-used.

R1, R2, R7 - 5w carbon.
R3, R4, R5 - 50w power.
R6 - cement.
D1, D2 - 1000v 10A rectifier.
C1, C2 - 100uF electrolytic.
C3 - 220uF electrolytic.

Insulation inside the wooden box provided by 2 mm Phenolic resin paper based Sheet.

DC circuit is great on Multisim, not too bad off-load on the bench.

Still working on the radio set, it has had a lot of tinkering and additional parts added in it's life, trying to remove and follow the circuit diagram and put my own spin on bypassing the canned condensers, which I think the previous owner was trying to do

Replacement valves obtained.

Fingers crossed, rubber mat in place, goggles on..
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Old 29th Oct 2020, 11:08 am   #7
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Default Re: Philips 830C here we go....

Hey, nice looking enclosure!

The bleeder resistors are very high in value. If you want a reasonable time to discharge to a safe level, you should be going a lot lower.

I'm curious why you need to waste so much power in heat and run such a hot unit. What's the thinking behind these resistor values?

It's possible to make a very light, neat, SMPS style inverter for radio HT that can run on a 9V battery for plenty enough output.
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Old 29th Oct 2020, 2:24 pm   #8
Scotorvm
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by astral highway View Post
Hey, nice looking enclosure!

The bleeder resistors are very high in value. If you want a reasonable time to discharge to a safe level, you should be going a lot lower.

I'm curious why you need to waste so much power in heat and run such a hot unit. What's the thinking behind these resistor values?

It's possible to make a very light, neat, SMPS style inverter for radio HT that can run on a 9V battery for plenty enough output.
Just parts that I already had, still learning, thanks for the comment and suggestions
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Old 29th Oct 2020, 3:02 pm   #9
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Default Re: Philips 830C here we go....

From what I understand you are using a 240-120V step down transformer. This is very likely to be an auto-transformer so will not provide any isolation from the mains so the set will have a live chassis. It needs to be good for at least 50W.

I think you would have been better off using your original bridge rectifier design and that would work out at at around 150-160V DC after a bit of filtering. According to radiomuseum there are multiple versions of the 830C for different DC mains voltages, what version is yours?
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Old 29th Oct 2020, 5:58 pm   #10
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by Scotorvm View Post

Just parts that I already had, still learning, thanks for the comment and suggestions
Hi again Lee,

A few things aren't clear:

1) In your post #5 You talk about it not being easy 'to produce stable 230 VDC' but I don't see at all where you are getting the sense that you need this over-high voltage. I had a look online at the trader sheets and they list a variety of anode voltages for the different stages (in German, but it's clear what they mean), depending on the voltage setting selected. They are a lot lower than 230V

See for example PJL's comment on a voltage of 150-160VDC in post #9.

So when I'm talking about heat etc, it's because the initial design should be focussed on producing your target voltage with minimal losses. It isn't a good design to dissipate unnecessary heat. That's not just an aesthetic thing, it's good sense as heat increases fire risk etc.

2) Please can you post more photos of the underneath, where you have mounted the power resistors and some mains earthing arrangements?

Perhaps if in light of the above, you could be really clear what voltage you are looking to produce, on and off load, and why, that would help things along.

It's always nice to use what's to hand, but it doesn't make sense to try to shoehorn a design out of unsuitable components.


Cheers...
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Old 7th Nov 2020, 10:47 pm   #11
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Default Re: Philips 830C here we go....

Thanks guy's.

Not sure how to respond, hence the delay..

OK, so my original bridge rectifier design, the resistors got so hot, could not touch. Sizzling hot.

The design with the transformer is a lot cooler.

I think I have the 1928 model. The barretter is a UL28, I am assuming 1928

According to radio museum Type 1928: 190-260 Volt DC mains.

That's why I have tried to construct a DC voltage in that range.

I have not powered this up as yet.

When I received this set a single diode and capacitor where across the AC mains voltage.

Next issue I have is Valve 4..

According to Radio Museum should be a B 2043, when I received this set it had a 16v Cossor 0.25A valve. Which did fit nicely.

So bought a compatible valve type RENS 1823d, only issue with this is the side screwed connector, it snags on the side wall of the valve holder and the valve goes in squint, also I don't have a wire on this set to connect to this connector.

Makes me think or (thik), not sure if I have got this all wrong.

PS

I did a lot of googling re 230VDC supply there where not a lot of options out there. A few on Indian websites but nothing really concrete, hence why I tried my own design.
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Old 8th Nov 2020, 11:06 am   #12
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Default Re: Philips 830C here we go....

Hi Lee

Just wonder if one of those battery ellimators would do, the one that produces 120V it may be a much safer way of providing power for the set in question, in any case best to avoid the heat, risk of fire and worse getting a shock from mains.

Ken
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Old 8th Nov 2020, 11:44 am   #13
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Default Re: Philips 830C here we go....

According to the manual it needs a DC supply of 210mA for 220 volts, the current will be a bit higher for 240-250 volts, any limiting resistor in series with a rectifier will get very hot unless it's suitably sized because of the charging current into the reservoir capacitor, to get the correct DC voltage out, the reservoir capacitance will need to be sized accordingly.

Lawrence.

Last edited by ms660; 8th Nov 2020 at 12:03 pm. Reason: correction
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Old 8th Nov 2020, 12:30 pm   #14
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Default Re: Philips 830C here we go....

Hi Scotorvm

I have an 830 which I haven't restored yet. I also have its successor from 1934, the 834C, so I am familiar with this era of set. Some say there is the right way, the wrong way and the Philips way ! The 834C has the longest warmup time of any set I own, nearly 2 minutes.

The DC mains supplies in the 1930's would have been anything but clean, hence the common mode filter choke and the HT choke S3. Note that just to confuse, Philips schematics show windings as zigzags and resistors as castellations. The mains ripple and noise would probably have been at higher frequencies than 100 Hz. In those days large value smoothing caps weren't practical, so one sees modest values combined with series iron cored chokes to give decent overall smoothing. Nowadays a 100 uF HT smoother is nothing special but chokes are expensive.

The LT current demand is 180 mA, and with four 20V valves in series that tots up to 80V. The rest of the 190 to 260 V DC input voltage is "lost" in the barretter which acts as a constant current device to allow for some variation in supply voltage. Larger variations are catered for by fitting different types of barretter.

When it comes to the HT side of things, Philips didn't see fit to change anything for different mains voltages. At 220V DC input the HT drain according to the data sheet tots up to about 30 mA, and less at lower voltages.

Your outboard DC power supply therefore needs to source a more or less constant current of about 200 mA at somewhere between 190 and 260 volts. The ripple at 100 Hz will be smoothed a little by S3, so it doesn't need to be ultra-clean.

In the interests of low heat in the radio, I would be inclined to aim closer to the 190 volt end which will give it a dissipation of about 40 watts.

I confess I don't understand all the resistors in your simulation

Assuming you have a 2:1 ratio step-down transformer fed with 240V AC, that's 120 V AC on the secondary. You then have effectively one halfwave rectifier with a capacitor input filter which will produce DC at the peak value of plus 170 volts. You have another halfwave rectifier producing minus 170 volts. The total across both capacitors will therefore be 340 volts, a voltage doubler arrangement. To drop this down to 190 volts you would need lose 150 volts. If you used a series resistor it would need to be 750 ohms and would be dissipating 30 watts which does seem mighty inefficient. If you want to keep this rectifier arrangement I suggest you try and source a transformer with an isolated (safer) secondary winding with a voltage of nearer 65 volts, or maybe two secondaries in series of 30 volts each. Something out of an old transistor HiFi amplifier might suit.

Alternatively, a 120 V AC secondary feeding a bridge rectifier and single smoother cap will give 170 volts DC. Although this is a little on the low side it might be enough for the radio to work so could be worth a try. Bear in mind that the 120V autotransformer gives no isolation from the mains, so the radio must be treated as live chassis.

Regarding the B2043 output valve, I suspect that this was available with more than one type of base. Some pentodes have Grid 3 connected internally to the cathode, to reduce the number of pins needed. The types with a side terminal for Grid 2 are not compatible with a recessed valveholder. Grid 2 should connect directly to HT positive, as per the schematic.
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Old 8th Nov 2020, 5:12 pm   #15
Scotorvm
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by Radio Tech View Post
Hi Lee

Just wonder if one of those battery ellimators would do, the one that produces 120V it may be a much safer way of providing power for the set in question, in any case best to avoid the heat, risk of fire and worse getting a shock from mains.

Ken
Thanks Ken, I'm sure I will solve this at some stage, will just take me a while
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Old 8th Nov 2020, 5:17 pm   #16
Scotorvm
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by ms660 View Post
According to the manual it needs a DC supply of 210mA for 220 volts, the current will be a bit higher for 240-250 volts, any limiting resistor in series with a rectifier will get very hot unless it's suitably sized because of the charging current into the reservoir capacitor, to get the correct DC voltage out, the reservoir capacitance will need to be sized accordingly.

Lawrence.
Cheers Lawrence
Will certainly take this on board will go back to my supply and have another look, 0.21A at 220vdc should be achievable
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Old 8th Nov 2020, 5:28 pm   #17
Scotorvm
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Default Re: Philips 830C here we go....

Quote:
Originally Posted by Mr 1936 View Post
Hi Scotorvm

I have an 830 which I haven't restored yet. I also have its successor from 1934, the 834C, so I am familiar with this era of set. Some say there is the right way, the wrong way and the Philips way ! The 834C has the longest warmup time of any set I own, nearly 2 minutes.

The DC mains supplies in the 1930's would have been anything but clean, hence the common mode filter choke and the HT choke S3. Note that just to confuse, Philips schematics show windings as zigzags and resistors as castellations. The mains ripple and noise would probably have been at higher frequencies than 100 Hz. In those days large value smoothing caps weren't practical, so one sees modest values combined with series iron cored chokes to give decent overall smoothing. Nowadays a 100 uF HT smoother is nothing special but chokes are expensive.



The LT current demand is 180 mA, and with four 20V valves in series that tots up to 80V. The rest of the 190 to 260 V DC input voltage is "lost" in the barretter which acts as a constant current device to allow for some variation in supply voltage. Larger variations are catered for by fitting different types of barretter.

When it comes to the HT side of things, Philips didn't see fit to change anything for different mains voltages. At 220V DC input the HT drain according to the data sheet tots up to about 30 mA, and less at lower voltages.

Your outboard DC power supply therefore needs to source a more or less constant current of about 200 mA at somewhere between 190 and 260 volts. The ripple at 100 Hz will be smoothed a little by S3, so it doesn't need to be ultra-clean.

In the interests of low heat in the radio, I would be inclined to aim closer to the 190 volt end which will give it a dissipation of about 40 watts.

I confess I don't understand all the resistors in your simulation

Assuming you have a 2:1 ratio step-down transformer fed with 240V AC, that's 120 V AC on the secondary. You then have effectively one halfwave rectifier with a capacitor input filter which will produce DC at the peak value of plus 170 volts. You have another halfwave rectifier producing minus 170 volts. The total across both capacitors will therefore be 340 volts, a voltage doubler arrangement. To drop this down to 190 volts you would need lose 150 volts. If you used a series resistor it would need to be 750 ohms and would be dissipating 30 watts which does seem mighty inefficient. If you want to keep this rectifier arrangement I suggest you try and source a transformer with an isolated (safer) secondary winding with a voltage of nearer 65 volts, or maybe two secondaries in series of 30 volts each. Something out of an old transistor HiFi amplifier might suit.

Alternatively, a 120 V AC secondary feeding a bridge rectifier and single smoother cap will give 170 volts DC. Although this is a little on the low side it might be enough for the radio to work so could be worth a try. Bear in mind that the 120V autotransformer gives no isolation from the mains, so the radio must be treated as live chassis.

Regarding the B2043 output valve, I suspect that this was available with more than one type of base. Some pentodes have Grid 3 connected internally to the cathode, to reduce the number of pins needed. The types with a side terminal for Grid 2 are not compatible with a recessed valveholder. Grid 2 should connect directly to HT positive, as per the schematic.
Thanks Mr 1936 for such a detailed reply, will need to revisit my PSU at some stage, seems I've mucked it up great info

Re the valve holder can only assume that someone replaced the original, not sure, but something else for me to figure out

Cheers
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Old 15th Nov 2020, 4:17 pm   #18
Scotorvm
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Default Re: Philips 830C here we go....

Following advice from forum members, PSU supply has been re-jigged..

OK, so powered the set up with my existing PSU, 48v was measured between the chassis and mains earth.

So thanks for the heads up with that issue.

Transformer now in place is Toroidal Transformer, 40mm x 90mm, 80 VA, 2 x 55V, 730 mA, Chassis, 230V, VTX Series.

Output linked to provide 110vac, to metal 60A rectifier, 100uF smoothing cap.

Powered set up, chassis now safe, 0v to earth. 170vdc measured at the barratter, so hopefully will be good to power the set, 20v short of the recommended though. If I need at least 190vdc, Plan B will involve information provided by members to, so thank you..

Have ordered a NOS B2043 valve to suit a recessed base 6-pin (50) as opposed to my 5 pin + side connector valve

Seems expensive, I think I could have frigged the side connector with a wire to run to the base, but will keep as a souvenir of my lack of knowledge...

Just need to check voltages at all the valve holders, noticed the dial lamp not lit, so need to check that to.
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