Chinese valve FM receiver kit - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

dodgy-dxer · 21st Apr 2014, 2:31 pm

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

dodgy-dxer · 22nd Apr 2014, 1:45 pm

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

Courtney Louise · 22nd Apr 2014, 3:50 pm

would you use the battery to make L1 also?

mole42uk · 22nd Apr 2014, 5:05 pm

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

mole42uk · 22nd Apr 2014, 5:07 pm

Thanks Fred!

I can see I'll now have to switch the soldering iron on....

Richard

Courtney Louise · 22nd Apr 2014, 6:28 pm

I have one of these kits too but havent started it yet

mole42uk · 22nd Apr 2014, 8:19 pm

You also bought one of the amplifier kits I remember - did that go together okay?

Does it sound good?

Richard

Courtney Louise · 23rd Apr 2014, 7:38 am

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.

Hybrid tellies · 23rd Apr 2014, 11:48 am

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.

mole42uk · 23rd Apr 2014, 3:10 pm

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

Courtney Louise · 23rd Apr 2014, 4:12 pm

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.

mole42uk · 23rd Apr 2014, 5:58 pm

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.

Courtney Louise · 23rd Apr 2014, 7:55 pm

If it would manage on 60v then you could try 5 of the 12v car alarm fob batteries.

Herald1360 · 23rd Apr 2014, 11:43 pm

That would be small, but I bet it's more expensive than 7 cheap PP3s.

Courtney Louise · 24th Apr 2014, 6:52 am

not if you get them from the same place the radio kit came from. £5 or less for 10

Courtney Louise · 6th May 2014, 6:01 pm

Hi Richard, how have you got on with this?

mole42uk · 6th May 2014, 7:38 pm

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

21st Apr 2014, 2:31 pm	#21
dodgy-dxer Heptode Join Date: Mar 2008 Location: Newmarket, Suffolk, UK. Posts: 612	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
dodgy-dxer Heptode Join Date: Mar 2008 Location: Newmarket, Suffolk, UK. Posts: 612	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
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	Re: Chinese valve FM receiver kit would you use the battery to make L1 also? __________________ *33, 45, 78, around and around they go...*

22nd Apr 2014, 5:05 pm	#24
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	Re: Chinese valve FM receiver kit I have one of these kits too but havent started it yet __________________ *33, 45, 78, around and around they go...*

22nd Apr 2014, 8:19 pm	#27
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	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. __________________ *33, 45, 78, around and around they go...*

23rd Apr 2014, 11:48 am	#29
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	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. __________________ Simon BVWS member

23rd Apr 2014, 3:10 pm	#30
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	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. __________________ *33, 45, 78, around and around they go...*

23rd Apr 2014, 5:58 pm	#32
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	Re: Chinese valve FM receiver kit If it would manage on 60v then you could try 5 of the 12v car alarm fob batteries. __________________ *33, 45, 78, around and around they go...*

23rd Apr 2014, 11:43 pm	#34
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Chinese valve FM receiver kit That would be small, but I bet it's more expensive than 7 cheap PP3s. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

24th Apr 2014, 6:52 am	#35
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	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 __________________ *33, 45, 78, around and around they go...*

6th May 2014, 6:01 pm	#36
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	Re: Chinese valve FM receiver kit Hi Richard, how have you got on with this? __________________ *33, 45, 78, around and around they go...*

6th May 2014, 7:38 pm	#37
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,608	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