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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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21st Apr 2014, 2:31 pm | #21 |
Heptode
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 612
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Re: Chinese valve FM receiver kit
Richard
My rusty brain started working I have asked my "Man in Macau" to take a look! He is both Chinese and RF professional/technical, although not a ham Fred |
22nd Apr 2014, 1:45 pm | #22 |
Heptode
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 612
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Re: Chinese valve FM receiver kit
Dear Richard
This is what Stephen has sent to me:- >> Hi Fred, here is what it means: (was jpg of that part of the message in his email text) L1 - use diameter 1mm wire and make 2 turns L2 - use diameter 1mm wire, use an AA battery as a core to make 4 turns, then take away the battery so i think you are right. >> Good luck Fred |
22nd Apr 2014, 3:50 pm | #23 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
would you use the battery to make L1 also?
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22nd Apr 2014, 5:05 pm | #24 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
I think I probably will use the AA battery for L1 to see if it works and may modify it if necessary.
The thing about L1 is that it needs to match an aerial into the circuit at about 100Mc/s and, of course, there's no specification for the aerial. Lots of speculation here in Bristol! Richard |
22nd Apr 2014, 5:07 pm | #25 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
Thanks Fred!
I can see I'll now have to switch the soldering iron on.... Richard |
22nd Apr 2014, 6:28 pm | #26 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
I have one of these kits too but havent started it yet
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22nd Apr 2014, 8:19 pm | #27 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
You also bought one of the amplifier kits I remember - did that go together okay?
Does it sound good? Richard |
23rd Apr 2014, 7:38 am | #28 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
Went together fine and have just bought the matching 4 input preamp. It sounds outstanding to be honest. I use it a couple of hours a day as my bedroom sound system.
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23rd Apr 2014, 11:48 am | #29 |
Nonode
Join Date: Jan 2004
Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area.
Posts: 2,965
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Re: Chinese valve FM receiver kit
Looks like an interesting project. I will be amazed if it works where I live, as FM reception can be challenging to say the least. But with my birthday coming up I could be tempted to put an order in.
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Simon BVWS member |
23rd Apr 2014, 3:10 pm | #30 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
Well, I'm soldering it together today so, as soon as the HT batteries arrive we'll see....
I'm in my workshop in the centre of Bristol just now where the little radio will get it's first test, and then I'll see what happens at home, near Westbury-on-Trym. VHF broadcast signals are not too bad in the city centre, but it's a bit more trouble at home. Richard |
23rd Apr 2014, 4:12 pm | #31 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
I was contemplating running mine on one of those cheap nixie clock power supply boards from a 9v adapter. They should be adjustable down to about 100v and then use something to drop another 10. The 1A2 is rated at 90v max.
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23rd Apr 2014, 5:58 pm | #32 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
I thought about a power supply like that, but I bought ten PP3s for less than 50p each, so why not? If I solder seven of them together it's a portable receiver!!
I was interested to note the HT on the diagram calls for 67 volts which is the old 467 battery size. I wonder if someone in China is making them? 67.5 volts is also the rated maximum for g2 + g4 + a when the valve is used as an oscillator. |
23rd Apr 2014, 7:55 pm | #33 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
If it would manage on 60v then you could try 5 of the 12v car alarm fob batteries.
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23rd Apr 2014, 11:43 pm | #34 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
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Re: Chinese valve FM receiver kit
That would be small, but I bet it's more expensive than 7 cheap PP3s.
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24th Apr 2014, 6:52 am | #35 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
not if you get them from the same place the radio kit came from. £5 or less for 10
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6th May 2014, 6:01 pm | #36 |
Octode
Join Date: Sep 2005
Location: Welshpool, Powys, Wales
Posts: 1,327
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Re: Chinese valve FM receiver kit
Hi Richard, how have you got on with this?
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33, 45, 78, around and around they go...
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6th May 2014, 7:38 pm | #37 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Chinese valve FM receiver kit
I finally received the batteries today and connected them - 'D' cell for the heater and 7 x PP3 for the HT
Audio out was disappointing, although the kit seems to give some signs of life (motor boating at certain combinations of variable pot and variable capacitor) but nothing resembling a received signal. More information as soon as I have something to report..... I got sidetracked this evening tracking down a couple of high-value resistors in my Murphy A188C so the little Chinese kit has to wait! Richard |