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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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28th Aug 2013, 12:22 pm | #1 |
Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,518
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Russian R154-2M
Currently having a play with this Reciever - very little available info - have ordered what I think to be a repair manual from Germany.
Biggest current issue however is that of the case being around 118v AC above true earth. Now, I really wish to avoid the whole PME/Mains Earth/True Earth debate, but need a sanity check. I have checked true earth to mains earth voltage in my shack - I get about 2v AC, which is normal. I have also checked other equipment in the shack to see if it is an issue with the power supply to the antenna tuner - again, about 2v from mains earth to each bit of kit. So, I was thinking that there may well be a couple of caps across the mains to chassis on this unit - have meggered the various points within the set to chassis, including phase and neutral to chassis, all test perfectly. Looking for ideas and inspiration! Cheers Sean
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28th Aug 2013, 12:31 pm | #2 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
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Re: Russian R154-2M
Connect a suitable resistor say 10k ohms between the chassis and mains earth. The voltage across it will tell you how much current is available. If it is only a mA or two it should be safe to earth the chassis permanently. It would still be worth finding the source of the current to make sure it is not a fault.
Al
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28th Aug 2013, 1:56 pm | #3 |
Dekatron
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Re: Russian R154-2M
Hmm, 4mA through 10K to deck......
Not healthy. Being modular (to an extent) I have been able to narrow it down to the power supply unit/IF stage chassis. I think circuit diagrams are required - lots of odd things happen inside this set. Safety is decadent Komrade.
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28th Aug 2013, 2:48 pm | #4 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
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Re: Russian R154-2M
That would equate to a 47nF capacitor from L to E. I have just looked at a filtered IEC inlet and the equivalent cap is 2.2nF. Big difference.
Al
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28th Aug 2013, 3:14 pm | #5 |
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Re: Russian R154-2M
If you have one of those multimeters with a capacitance range, give it a try.
David
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28th Aug 2013, 4:24 pm | #6 |
Dekatron
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Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
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Re: Russian R154-2M
Well, had a rummage through the set - there is a discrete mains filter, with 6 poles!
Sadly it would appear that the caps used are a little marginal at 240v - insulation resistance is fine at over 50Meg! With the filter bypassed leakage drops to a very acceptable 0.2ma I think a new, modern mains filter will be in order.
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28th Aug 2013, 6:08 pm | #7 |
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Re: Russian R154-2M
I suggest a Corcom or Japanese mains filter. Some Schaffner ones, I found, have golden stink-bombs inside.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
28th Aug 2013, 8:26 pm | #8 |
Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
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Re: Russian R154-2M
Well, it gets better - the BFO has now decided to stop working! - Manual on it's way from Germany - My German is much better then my Russian!
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28th Aug 2013, 8:50 pm | #9 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
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Re: Russian R154-2M
Hi Sean,
You're welcome to one of these, from a box of oddments I acquired recently. |
29th Aug 2013, 10:09 am | #10 |
Dekatron
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Re: Russian R154-2M
Thanks Bill, I have rebuilt the discrete filter using modern components - seems a shame to dump such a nice diecast chassis - it also filters all of the HT and LT lines that feed other modules.
Onto the BFO when the manual arrives.
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