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


It is currently Nov Wed 13, 2019 3:56 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 32 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: A 1947 Magnavox
PostPosted: Dec Mon 14, 2015 10:02 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
It's also my first console. It's a 153b Hepplewhite. It doesn't have it's turntable but I intend on using my music files for play with it. It has an optional FM tuner in a freestanding album case. I found it here on Craigslist and it has Chicago area preset labeling.


Attachments:
20151212_115530.jpg
20151212_115530.jpg [ 163.34 KiB | Viewed 6260 times ]

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke
Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Dec Mon 14, 2015 10:08 pm 
Member
User avatar

Joined: Mar Tue 04, 2014 3:29 am
Posts: 2073
Location: Long Beach, CA 90808
That freestanding FM Tuner with the vertical tuner is a SUPER rare find!!

_________________
Aloha, Ken

No Console Left Behind!
Come join us @ http://vintagehifi.net/


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Dec Mon 14, 2015 10:14 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I just got a technical bulletin for it on Ebay. It is a CR192.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Dec Mon 14, 2015 11:02 pm 
Member
User avatar

Joined: Dec Wed 25, 2013 7:57 am
Posts: 3871
Location: USA
Wow! Nice. Too bad we can't accumulate them like some of us do with small AA5's. My Magnavox was rescued from a guy who couldn't find the time to rip out the electronics and make it into a wine cabinet. Not only you have the rare dual tuner set up, looks like you have a perfect space there for a TV too.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Dec Tue 15, 2015 2:03 pm 
Member

Joined: May Tue 01, 2007 4:01 am
Posts: 1712
Location: Hamilton Square, New Jersey
I believe that's the Hepplewhite model. You can score the Webster record changer on EBay. They are there all the time. This console will definitely need recapping.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Dec Tue 15, 2015 2:14 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
With my laptop library, I can take my time on finding a turntable for it. I have the receiver out now and giving it a clean and have checked the tubes. It has a failed 6SK7 IF amp. I have caps to order to start the recap. It looks to have mighty accessible components as opposed to some of the ship in a bottle style layouts I have seen. :D

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Sat 09, 2016 1:10 am 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I finished the recap on the receiver in time for new years. I had to perform a small repair on one speaker cone. It appeared to have had a loose wire or some other object rubbing against it wearing about a 1.5 inch hole in it. it was easy to get to and is sound now. I replaced the resistors for the tuning indicator tube also and it functions nicely as well.

Attachment:
P1000850.JPG
P1000850.JPG [ 53.35 KiB | Viewed 6037 times ]


Attachment:
P1000851.JPG
P1000851.JPG [ 59.42 KiB | Viewed 6037 times ]


It sounds nice so far and I replaced the old multi pin phono connector on the receiver with a RCA jack. It works well with the laptop music library. 'Til I'm able to finish up on the FM converter I found a Sansui PLL digital AM/FM tuner for $7.00 to provide FM input for the time being.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Last edited by 19&41 on Jan Tue 12, 2016 2:37 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Tue 12, 2016 12:47 am 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
The FM converter continues to be difficult. The tuning indicator on it has a decent open indication but will not close when on a station. The unit will provide decent output to the console's receiver until any vibration or the slightest jar of the limiter tube. The schematic calls for a 6SH7 tube, and there is a glass envelope 6SH7GT tube installed. The signal to the receiver is lost when the tube is even touched lightly.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Tue 12, 2016 2:06 am 
Member
User avatar

Joined: Nov Tue 05, 2013 4:38 pm
Posts: 1256
Location: Windsor ,Ontario, Canada
You may need to tighten up the contacts in the socket to hold the tube pins. Also give it a good cleaning along with the tube pins.

_________________
Dwayne


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Tue 12, 2016 1:47 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 20330
Location: Warner Robins, GA
That looks just like a CR-198 console

See if you can find that number on the console or chassis anywhere. There may be a letter after the CR-198 which is important to getting the correct schematic as the CR-198 had several changes done to it through its production run.

Provided this is indeed a CR-198 there's three issues.

1. Lack of lower bass response.
2. No tweeters (only an issue if using the console for HI-FI reproduction)
3. Rolled off upper treble (only an issue when #2 fixed)

1. The lack of bass response can be fixed by doing three things.
A. Replacing the speakers with a pair of better 12" electrodynamic speakers. I used a pair of Capeheart (made by Jensen as I recall) 12" speakers with the 700 ohm field coils wired in parallel and a 150 ohm resistor in series to equal the 500 ohm resistance that is expected.
B. Modifying the bass control circuit which requires also removing the feedback to that control. That will give you a console radio sound with the control full CCW and more of a HI-FI bass sound plus a slight bit of extra audio gain when the bass control is full CW.
C. Replacing the output transformer with a better one.

2. Add a pair of Isophon DP-19 tweeters which match up perfectly to the mouthing holes for the metal cones mounted to the speaker baffle. I'm sure other tweeters will work perhaps even some of the 5" round Magnavox tweeters made by Heppner.

3. Is caused by Miller effect and can be fixed by replacing the 6J5 first audio tube with a pentode. Improvement can also be made without using a pentode as the first audio tube by replacing the audio cables that go from the bandswitch through a spring shield on the chassis to the volume control then to the first audio tube with good quality shielded cable, but won't completely cure the problem.

All three fixes are very important if you plan on using this for true HI-FI listening.

Also if it seems like the console just don't sound like it's putting out 20 watts, the output transformer will have a shorted turn or turns and will require replacement, but if you fixed the bass response issue it will have already been replaced anyways.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Fri 15, 2016 5:33 pm 
Member

Joined: Nov Wed 27, 2013 5:59 am
Posts: 681
Location: Metzger Oregon
I picked up one of these with a delaminated cabinet last year, let me know if you would like the record changer.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Fri 15, 2016 7:26 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
Thanks for the responses, Tube Radio, The receiver is a CR-198C. The console performs as well as I would like, I have a modern stereo system to do the necessary higher fidelity tasks, although I appreciate the advice. And thanks Classicelectronicsguy for the kind offer. Let me see How time and finance bear up for me in the next 2-3 weeks.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Sat 16, 2016 6:28 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I had ordered a metal envelope 6SH7 tube to replace the microphonic 6SH7GT glass envelope tube in the FM converter. I installed it and re aligned the discriminator, then set it up on the antenna. The converter operates just fine now. Now the last problem with it is to get the open eye to indicate.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Sat 16, 2016 9:46 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 20330
Location: Warner Robins, GA
19&41 wrote:
Thanks for the responses, Tube Radio, The receiver is a CR-198C. The console performs as well as I would like, I have a modern stereo system to do the necessary higher fidelity tasks, although I appreciate the advice. And thanks Classicelectronicsguy for the kind offer. Let me see How time and finance bear up for me in the next 2-3 weeks.


You're welcome.

If you need a full copy of the schematic I can email it to you.

The schematic in Riders is split into two pages.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Sat 16, 2016 10:38 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I have a high res schematic dvd, and that worked well for the job. That has been the most value for the dollar of any service items I have gotten.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Jan Sat 16, 2016 11:48 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 20330
Location: Warner Robins, GA
Awesome


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Feb Mon 01, 2016 9:53 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I set up a hidden long wire antenna for the console this last weekend. It has improved the reception immensely. The shortwave receiver is a good performer.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Feb Mon 08, 2016 8:38 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
I had been looking for a MPX stereo era Magnavox console for a long while before this one came along. I'm pleased with this one. It's been fun to work with and plays well. It is even a pretty good shortwave performer. Reading about shortwave traffic here, I thought it was just about dried up. I have been listening to a number of stations' English services and with the antenna they come in better than the clear channel stations 30 miles away. I was surprised to hear RTTY traffic as well. This thing has brought back a little of the magic of radio from my youth.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Feb Mon 08, 2016 10:23 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 20330
Location: Warner Robins, GA
Very nice.

If you want to add BFO capability (provided the oscillator is fairly stable) get an LM series or BC series frequency meter.

You just connect a wire to the frequency meter, loose couple it to the antenna then set the frequency meter to the desired receive frequency.

Other real stable oscillators that can cover the SW frequencies the Magnavox receives such as a good RF generator will work as well.


Top
 Profile  
 
 Post subject: Re: A 1947 Magnavox
PostPosted: Feb Mon 08, 2016 10:29 pm 
Member
User avatar

Joined: Apr Thu 21, 2011 2:00 am
Posts: 4261
Location: Georgia, 30236
Thanks, I appreciate that.

_________________
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke


Top
 Profile  
 
Post New Topic Post Reply  [ 32 posts ]  Go to page 1, 2  Next

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