Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Tue 16, 2019 7:51 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 15 posts ] 
Author Message
 Post subject: QST two tube superhet
PostPosted: May Tue 14, 2019 2:07 am 
Member

Joined: Nov Thu 16, 2017 12:30 pm
Posts: 37
Location: Forest Acres, S.C.
Hello all,

I am back once again with another question. Two years ago I started building this two tube superhet. It uses a 6K8 and 6C8. I never finished it and now I want to complete the build. The problem is I still have the schematic diagram but I lost the notes on the build, and I am no longer a member of ARRL, so I have lost access to the QST archive. Does anyone know of the circuit I am referring to, or have access to QST?

Tnx,

Robert


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 3:06 am 
Member
User avatar

Joined: Sep Mon 16, 2013 2:42 am
Posts: 3285
Location: Tucson, Arizona U.S.A.
In my very incomplete index I have the following entries:

The Novice Special (two tubes), QST, June 1956 page 34

Selectivity With the 2-Tube Regenerative Receiver (use a short antenna), QST, January 1939 p 36. As I remember, this one used 2.5 V tubes but I might be wrong.

Here is a web site that has older QSTs: http://www.rsp-italy.it/Electronics/Magazines/QST/

Good luck. If you find it tell us where.

_________________
Jim Mueller


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 3:47 am 
Member

Joined: Nov Thu 16, 2017 12:30 pm
Posts: 37
Location: Forest Acres, S.C.
Jim,

Thank you very much. I found it in the February 1941 issue, page 12.


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 5:19 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2284
Location: Saskatoon
It also appeared in the ARRL Handbook for several years.


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 3:26 pm 
Member

Joined: Nov Thu 16, 2017 12:30 pm
Posts: 37
Location: Forest Acres, S.C.
I have another question. On my website http://www.kg4kgl.net, is a pair of circuit diagrams. I started building the first one. The second is from the Feb 1941 QST article. It has been two years and I am not sure where I got the first article. They are different. The QST article uses the triode of the 6K8 as an LO. Would the first circuit even work?


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 3:51 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 27707
Location: Detroit, MI USA
Yes, it appears to just be a different way of drawing the 6K8, in reality what they are showing as G2 on the tube is the triode plate.

That tube drawing more closely resembles a 6A8 or 6A7 than it does a 6K8 but if you understand the internal construction of the 6K8, it seems the circuit would oscillate.

_________________
Dennis

Experience is what you gain when the results aren't what you were expecting.


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 5:45 pm 
Member

Joined: Nov Thu 16, 2017 12:30 pm
Posts: 37
Location: Forest Acres, S.C.
Well I am comparing the two diagrams and the work that I have done so far, and it seems I do not need to undo anything. So I will just continue building it with the QST supplied schematic diagram.


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Tue 14, 2019 11:16 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13796
Location: S. Dartmouth MA 02748-1225 USA
Robert,

This sounds like a really fun project.

Would you mind posting with images along the way?

Minimalist radios fascinate me.

Chas

_________________
Smith's Ale Gives Strength, Smith Bros. Brewers, New Bedford MA


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Wed 15, 2019 2:03 am 
Member

Joined: Nov Thu 16, 2017 12:30 pm
Posts: 37
Location: Forest Acres, S.C.
Will do, but don’t expect much in the way of metal work. That is not my strong suit. :roll:


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Wed 15, 2019 7:41 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2284
Location: Saskatoon
Here's a link to the one that Exray built:
http://www.sparkbench.com/homebrew/grammar/grammar.html


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Fri 17, 2019 7:59 pm 
Member
User avatar

Joined: Aug Wed 25, 2010 3:23 pm
Posts: 1281
Location: WA 98407
I built it about a decade ago. A worthwhile project. Later, after finding an on-line article by W0VLZ about adding a third tube, I did that, too. Made it even better! In fact, he posted two articles: https://www.prismnet.com/~nielw/3tubrcvr/3tubrcvr.htm and https://www.prismnet.com/~nielw/3tube_xtal/3tube_xtal.htm. Pictures, schematics and parts list included.
If you find the metalworking a challenge, you could build it on a simple sheet of stout aluminum about 6 x 8", say 0.08" or 0.09" thick, and use wood for side supports. Here's mine:

Attachment:
P1080473.jpg
P1080473.jpg [ 99.58 KiB | Viewed 583 times ]

Tom


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Fri 24, 2019 12:07 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4607
Location: Eschew Obfuscation Virginia 23005
allthumbs wrote:
I built it about a decade ago. A worthwhile project. Later, after finding an on-line article by W0VLZ about adding a third tube, I did that, too. Made it even better! In fact, he posted two articles: https://www.prismnet.com/~nielw/3tubrcvr/3tubrcvr.htm and https://www.prismnet.com/~nielw/3tube_xtal/3tube_xtal.htm. Pictures, schematics and parts list included.
If you find the metalworking a challenge, you could build it on a simple sheet of stout aluminum about 6 x 8", say 0.08" or 0.09" thick, and use wood for side supports. Here's mine:

Attachment:
P1080473.jpg

Tom

Very nice!

BR,

Terry


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: May Wed 29, 2019 10:52 pm 
Member

Joined: May Fri 01, 2015 2:33 am
Posts: 1322
Location: Roslyn,Pa 19001
The 1/39 QST article does use the old skool 2.5v standard base tubes. The direct replacement would be 6D6 for the 58 and a 76 or 37 for the 56. The more modern self centering tubes would be the 6SK7 and 6J5 or 6C5. Fred Sutter the author was the guy that designed the famous QSL 40 transmitter series.

GL
The other Terry


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: Jun Thu 06, 2019 1:14 pm 
Member
User avatar

Joined: Jun Wed 08, 2011 2:33 am
Posts: 8695
Location: Ohio 45177
I have pored thru alot of old QST mags and drooled over some of the cool vintage projects. Then, flipping thru the magazine for a couple months later, read "In such and such article, resistor R12 should be 1000 Ohms, not 1 meg Ohm, and C11 is missing...".
I therefore consider maybe the handbook projects might be more trustworthy, as presumably they were debugged before being added. Having a sampling, not every issue, of old ARRL handbooks is nicer than the tons of magazines. Then having access to the online archives is nice if you know where to look.

_________________
Reddy Kilowatt says; You smell smoke? Sorry about that!


Top
 Profile  
 
 Post subject: Re: QST two tube superhet
PostPosted: Jun Sat 08, 2019 1:22 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1050
Location: St. Louis, MO, USA
I don’t know if it’s still in print, but QST published a collection of receiver projects from previous magazine articles. Worth a look.

Dennis


Top
 Profile  
 
Post New Topic Post Reply  [ 15 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 5 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB