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 Post subject: replacement for 6F7M
PostPosted: Jan Wed 20, 2010 7:02 am 
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Joined: Feb Mon 19, 2007 7:18 am
Posts: 353
Location: Jonquiere,Saguenay,Quebec CA
HELLO TO ALL

What can replace 6F7M ,TUBE .i am willing to change the socket and use another tube but what typt would be best.

Thanks for the inf.

bob


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 Post subject:
PostPosted: Jan Wed 20, 2010 7:15 am 
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Location: Aurora Colorado
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Hi Bob, have you tried posting in the classifieds for one. The M just means it's a metal shielded tube, you could sub a glass one, and use a shield with it. My book does not show a sub. David

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 Post subject:
PostPosted: Jan Wed 20, 2010 7:48 am 
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Location: Jonquiere,Saguenay,Quebec CA
hi

Can even find the data spec, these were made by rogers majestic ,forgot to mention it has 8 pin, its the second IF and AVC DIODE

I found the data for a 6f7 but it has 7 pins did they make 2 different typt 1= 8 pin and 1 = 7 pin.

thanks

bob


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 Post subject:
PostPosted: Jan Wed 20, 2010 8:15 am 
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Joined: Feb Mon 19, 2007 7:18 am
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Location: Jonquiere,Saguenay,Quebec CA
hi

LOOK IN MY OLD STOCK AND FOUND A 6f7m WITH 7 PINS AND IN THE SET THERES A 6f7M 8 pins .

WHAT A WORLD I ALWAYS TEND TO GET THESE KIND OF PROBLEMS.

BOB


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 Post subject:
PostPosted: Jan Wed 20, 2010 8:21 am 
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Oh, I did not know it was a Rogers tube.Someone posted a substitution booklet for the Rogers tubes here, may be in the photo gallery, I did download it, just have to find it on this computer. David

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 Post subject:
PostPosted: Jan Wed 20, 2010 9:17 am 
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Joined: Feb Mon 19, 2007 7:18 am
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Location: Jonquiere,Saguenay,Quebec CA
Hi


If you want to see the tube i have mention , go to nostalgia look up , roger majestic canadain model 10- 10 and have a look at the 6F7M, someone might be able to give me another tube number with 8 pins all i would have to do is change the wiring on the socket.

thanks for your help.

bob


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 Post subject:
PostPosted: Jan Wed 20, 2010 10:31 am 
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Location: Haledon, NJ, usa
Here's your 8 pin tube:
Image
According to this cross ref list there is NO American reference for it:
http://www.justradios.com/typeM.html

Seems like the American tube will work with a socket change. Maybe? I don't have the specs on the Rogers tube though.

But...The regular 7pin American version:
6F7 is Available here for $4 new and $2 used:
http://www.findatube.com/
Image Image

You may be able to use a 6P7G if you want to stick with 8 pins.
This tube is also available at http://www.findatube.com/ for $7.50 new and $3.50 used.


6P7G
Image

Hope this helps.

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 Post subject:
PostPosted: Jan Wed 20, 2010 2:31 pm 
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Location: Wangaratta, Victoria, Australia
Location: Wangaratta Victoria, Australia
That wiring diagram does not appear consistent with the standard 6F7 tube data. pin 1 &7 heaters looks like 2 & 7 which is the common pinout for octal heaters.

NB the non standard pin outs of 6P7. These tubes are similar to 6BL8 in there application, as they are also used for converters (frequency changers)

Data sheets on "Frank's electron tube pages"

Someone could have changed the base on the tube? It have seen it done. I have salvaged tube bases, without breaking anything. Normally they put a minature in a big socket.

Tubes like 6A7 & 6A8; 6D6 & 6U7; 80 & 5Y3 and others are the same tube with a different base & number. Check the pinouts of the 8 pin socket in that radio, against that of the 6P7.

I suspect some "customising" here? The original socket may have been broken and this was the fix?

Marc


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 Post subject:
PostPosted: Jan Wed 20, 2010 2:51 pm 
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It's not a custom job, that's a factory tube. In the Tube Lore #3 supplement 6F7M is listed along with the other Rogers M type tubes. You should be able to find one in Canada. A 6P7 may work but would requie rewiring.


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 Post subject:
PostPosted: Jan Wed 20, 2010 3:29 pm 
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Location: No. Hollywood, CA
Since the triode section of the 6F7M is being used as a simple diode, a relatively easy substitution would be metal type 6B8. Basing is the same as the 6F7M except that connections to pins 4 and 6 would have to be swapped.

Doug


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 Post subject:
PostPosted: Jan Wed 20, 2010 11:48 pm 
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Joined: Feb Mon 19, 2007 7:18 am
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Location: Jonquiere,Saguenay,Quebec CA
HELLO TO ALL

Thanks for all who answered my call for help , theres so many problem in this radio , that there are times that i feel like quitting after a day or so i am back at it.

I think i will go with DOUG opinion and used the 6B8, but to really be sure i do the right thing and see if i really understand DOUG explanation .

I disconnect both wires from pin 4 and 6 and switch them 6 becomes 4 and 4 becomes 6 am i right


many thanks to all


bob


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 Post subject:
PostPosted: Jan Thu 21, 2010 12:04 am 
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Joined: Apr Thu 02, 2009 6:32 pm
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Location: South Western Ontario Canada
Hi!
Peter is correct. According to the Rogers tube substitution guide that I have the 6P7G is a direct substitute for a Rogers 6F7M (metal spray) tube with no special notes for any rewiring or shielding needing to be added.
Bob Masse


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 Post subject:
PostPosted: Jan Thu 21, 2010 12:18 am 
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Joined: Apr Thu 02, 2009 6:32 pm
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Location: South Western Ontario Canada
Hi! Please disregard above info on the Rogers 6F7M tube. After some research my info was in error on that tube. The 6P7G will require a rewire to work. If you google "Pacific TV - Technical Data" and click on that link,then scroll down to "Rogers Tube Characteristics Chart " , you will find the tube info and pin locations you are looking for. Sorry about that previous info but that is what my chart said.
Bob Masse


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 Post subject:
PostPosted: Jan Thu 21, 2010 12:26 am 
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Joined: Feb Mon 19, 2007 7:18 am
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Location: Jonquiere,Saguenay,Quebec CA
THANKS BOB

Iwill certainly look into that this saturday ,i check just radio site , mention no replacement for 6F7M.

I would be very happy , if you were right ,not that i doubt your information not one minutes, i would be very happy.

bob and many thanks


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 Post subject:
PostPosted: Jan Thu 21, 2010 1:25 am 
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Location: No. Hollywood, CA
bobb12 wrote:
I think i will go with DOUG opinion and used the 6B8, but to really be sure i do the right thing and see if i really understand DOUG explanation .

I disconnect both wires from pin 4 and 6 and switch them 6 becomes 4 and 4 becomes 6 am i right?


Yes, you're right. To be more explicit for the 6B8 substitution:

1. Disconnect any and all wires or component leads on Pin 4 and move aside for future transfer to Pin 6.
2. Disconnect any and all wires or component leads on Pin 6 and reconnect them to Pin 4.
3. Reconnect all wires and/or component leads previously removed from Pin 4 to Pin 6.

Conversion for 6P7 is similar except requires moving wires and leads on pins 3 to 4, 4 to 5, 5 to 6, 6 to 7, and 7 to 3, in accordance with the diagrams previously posted by Peter.

Bob Masse -- thanks for the location of the Rogers tube characteristics table. It helped to be sure that the pin numbers I was reading from the Rogers schematic were correct.

http://members.shaw.ca/pacifictv2/rogerstubedata.jpg

Doug


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 Post subject:
PostPosted: Jan Thu 21, 2010 3:21 am 
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Location: South Western Ontario Canada
Just glad that got resolved without any electrical parts getting fried.
Bob Masse


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 Post subject: Re: replacement for 6F7M
PostPosted: May Sun 21, 2017 2:57 am 
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Joined: Oct Sun 05, 2008 5:47 am
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Location: Bothell, WA
I know this is an old thread, but I never did find any posts on how the 6B8G or 6P7G performed. I have a Rogers 6R1331 and it uses 3 6F7M tubes.

I used an octal socket converter so I didn't change the radio wiring. Should someone come along after me and try to put in a 6F7M they won't have any surprises.

I tested out the 6B8G and it worked fine for the 1st IF Amp/Aux AVC Diode and the Suppressor IF Amp. It didn't work on the 2nd IF Amp and AVC Diode. So it's close, but isn't a universal swap.

I tested out the 6P7G and it worked just fine in all positions. I'm comfortable that the 6P7G with proper wiring changes is a good replacement.

I want to thank everyone who participated in this thread for their help. It made things really straightforward for me.

Thanks again!

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 Post subject: Re: replacement for 6F7M
PostPosted: Feb Mon 15, 2021 7:57 am 
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Joined: Apr Sun 08, 2007 5:47 am
Posts: 5788
Location: British Columbia
cwysong wrote:
I know this is an old thread, but I never did find any posts on how the 6B8G or 6P7G performed. I have a Rogers 6R1331 and it uses 3 6F7M tubes.

I used an octal socket converter so I didn't change the radio wiring. Should someone come along after me and try to put in a 6F7M they won't have any surprises.

I tested out the 6B8G and it worked fine for the 1st IF Amp/Aux AVC Diode and the Suppressor IF Amp. It didn't work on the 2nd IF Amp and AVC Diode. So it's close, but isn't a universal swap.

I tested out the 6P7G and it worked just fine in all positions. I'm comfortable that the 6P7G with proper wiring changes is a good replacement.

I want to thank everyone who participated in this thread for their help. It made things really straightforward for me.

Thanks again!


Another Old Thread;
The 6P7/6P7G can work as a substitute for a 6F7M but they are also an uncommon tube, whilst a 6F7 is a much more common type, but with an old style base. The seven pin 6F7 was fairly popular, but the dual section idea fell out of favor when the octals arrived, in spite of their being octal versions offered, maybe because of the cost, who knows. For some reason RCA came up with the 6P7, as an octal replacement for a 6F7, but went with a non standard base, whereas Rogers went the standard route, but since Rogers Tubes LTD only operated in Canada the 6F7M became the oddball. The 6F7M, like a 6F7 is a pentode-triode, but in most cases they wired up the triode section as a diode. In such cases you can usually get away with using a 6B8, but apparently not always. In one set I have they used both 6F7Ms as If amplifiers, and used the triodes as detectors, so one could conceivably use a 6B8 in one hole, and a 6K7 in the other, by rewiring, somebody already messed around under the chassis so it isn't original now.
Regards
Arran


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 Post subject: Re: replacement for 6F7M
PostPosted: Feb Mon 15, 2021 4:51 pm 
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Posts: 936
Location: Ontario, Canada
Location: London Ontario Canada
Hi Bob
PM sent

John


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 Post subject: Re: replacement for 6F7M
PostPosted: Feb Tue 16, 2021 2:16 pm 
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Location: Latham NY 12110
Location: Latham NY 12110
Looks like both Bob's haven't been here in a long time.


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