DIY Audio Projects Forum
 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 31 Oct 2014, 21:24

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: Simple tube FM radio
PostPosted: 03 Mar 2011, 16:21 
Offline
User avatar

Joined: 23 Feb 2011, 16:31
Posts: 71
Location: Berlin / Germany
Hello friends of the elementary, simple radio.

Here is a wiring diagram and my experiment with the simplest FM receiver in the world.
Attachment:
simple UKW receiver.jpg

All connections to the tube EF98 should be as short as possible.
Attachment:
test raster board.JPG

An adjustable coil is here the best way to success. Don´t try an adjustable capacitor. The great mass of the rotor, is the problem in the FM resonant circuit.
Attachment:
UKW coil.JPG

best to all
Joe


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.



Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 12 May 2011, 14:53 
Offline
User avatar

Joined: 23 Feb 2011, 16:31
Posts: 71
Location: Berlin / Germany
Hi, Radiofriends

Now I want to install a high-frequency amplifier.
To this end, the circuit must also be installed in a shielded enclosure.

What do you think .....

Can I use an aluminum chassis or is a galvanized iron sheet better?

Greetings
Joe


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 27 May 2011, 10:01 
Offline

Joined: 23 May 2011, 11:58
Posts: 6
Location: Beautiful Blue Ridge Mountains Of Virginia
Boy, this is truly the simplest FM receiver I've ever seen. Nice, simple design. I would think that aluminum would be OK for RF shields, and is easy to work. To my thinking, iron(steel) is only needed when magnetic shielding is necessary. Good luck with this project. I might try something like this, myself.


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 27 May 2011, 13:28 
Offline
User avatar

Joined: 23 Feb 2011, 16:31
Posts: 71
Location: Berlin / Germany
Hi Billy,
thank you for this important information. The problem is that these
sort of FM- receiver are also FM- transmitter. The schematics is from
1949. It was developed by american radio amateurs. In the 50´s these receicer
were installed in old AM- radios. I don´t know the english word .....in German the name
is "Pendelempfänger". What´s the english word for these kind of radio ??
The shield is very important, because your neigbours get problems with their
FM-radio if you are near by.
For demodulation, the FM reciever works with a second frequence between 20-100kHz.
Here my next step.... the modification with an HF- amp.
The result is now not really perfect.
Attachment:
UKW Pendelempfänger mit HF Vorstufe.JPG

Cheers
Joe


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.



Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 05 Jul 2012, 14:27 
Offline
User avatar

Joined: 31 Dec 2008, 15:34
Posts: 335
Location: Denmark
Hi Joe

About the Pentode:
Do you think it's possible to use an EL84 and get it oscillate, instead of an EF98 ? Offcourse it's also necessary, to restructure the pins.
( why an EL84 ..i've got those. I don't have an EF98 )

About the UKW coil:
Is it possible to use some winded copper on a variable stick of ferrit ...and if, should the copper be silvered ?

_________________
Kramme


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 18 Jul 2012, 15:03 
Offline
User avatar

Joined: 23 Feb 2011, 16:31
Posts: 71
Location: Berlin / Germany
Hello Kramme,

sorry....late....
today I receive a message from DIY to my e-mail about this thread.
The message is indeed two weeks on the road ... ha, ha...modern times!

I used the EF98, because I wanted to use absolutely voltages less than 50VDC..
The EF98 is also suitable for high frequencies. EF95 and EF98 are particularly suitable for applications with very small Anode voltages. Simple MW / SW audion receiver for example.
The EL84 is a low frequency amplifier tube and not appropriate for RF at 100MHz.
Here is a nice link to a german radio website. There are different schematics
with different RF- tubes for UKW- Pendelempfänger and also the original
american stuff. My experiment with EF98.

http://www.jogis-roehrenbude.de/Bastels ... aenger.htm
http://www.jogis-roehrenbude.de/Bastels ... er/UKW.htm

The description is only in German. Please use a language tool.

@Kramme:
"Is it possible to use some winded copper on a variable stick of ferrit ...and if, should the copper be silvered ?"

Yes,..you need a VHF ferrite coil. The ferrit material is important.
Silver wire is particularly suitable for SW and FM (VHF).
To tune up, you can then screwing the core, or try it with a adjustable small
capacitor (Trimmer)

A well insulated screwdriver ... no metal ! (Amber or a good plastic tool)
is required.

Best regards

Joe


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 20 Jul 2012, 14:30 
Offline
User avatar

Joined: 31 Dec 2008, 15:34
Posts: 335
Location: Denmark
Hi Joe

Thanks for a good description ...i'll look for something usable ;)

_________________
Kramme


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 20 Jul 2012, 18:24 
Offline
User avatar

Joined: 23 Feb 2011, 16:31
Posts: 71
Location: Berlin / Germany
Hello Kramme,

Do you know the English word for "UKW- Pendelempfänger"?
There was no answer to my question in this thread. No chance
for a good...... Google translation! :!: :bawling:

If you are interested in radio experiments, for the low voltage range, then google for module bus.... or look to the link below.
There you find parts, tubes, and also two radio- kits RT 25 and RT100
with EF98 and 95. A free download (Schematics) is also possible.

http://www.ak-modul-bus.de/stat/experim ... steme.html

http://www.ak-modul-bus.de/stat/roehre_ef98.html

Here are also different links to german sites. If you need some old radio and electronic parts.
http://www.conrad.de/ce/de/FastSearch.h ... itial=true
http://oppermann-electronic.de/html/rundfunkrohren.html
http://www.pollin.de/shop/suchergebnis. ... T=R%F6hren


Have fun and greetings to Denmark

Joe


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 20 Jul 2012, 21:57 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 2418
Location: Arizona, USA
Hi Other tubes that might be more common and work in this circuit are the 6BC5, 6CE5, 6BA6, 6AU6, 6BZ6. The various pentagrid converter tubes like the 6BE6 and 6BA7 may also work if you tie some of the grids together. Scarcer but also good would be ones in the 6AK5 family. They were deigned to operate at very high freqs. There are also octals, I believe the 6SA7(pentagrid) , 6SJ7 and 6SK7 might work.

Good listening

Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: Simple tube FM radio
PostPosted: 20 Jul 2012, 22:18 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 3810
Location: Australia
Tube FM radio - that's a project I would never thought of. Is the audio quality high, clear and clean and hiss free?

_________________
Projects: "Parley" - Tube preamp with Pass B1 buffer | "VoXConcentriC" - Beyma high efficiency 12" speakers | "Black Lace" - all Ozzie tube 6V6 Power amp - old school
Website: [ retro-thermionic ]


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Opamp Projects :: DIY Phono Projects :: DIY Cable Projects :: HI-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy