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Convert Two 813 Tube SSB Amp To "AM"

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Author Topic: Convert Two 813 Tube SSB Amp To "AM"  (Read 15684 times)
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Posts: 104

« Reply #50 on: June 09, 2015, 06:35:32 AM »

Hi Ken,
For the panel labels....  perhaps the best idea is to get some clear plastic adhesive 8 X 11" sheets. They can be found on the web or at stationery stores.  Then use your computer and printer to print custom lettering.   Maybe the guys have other ideas.   I do like the ability to create any words, colors or font size myself vs: buying canned labels.  The clear material is transparent and makes the lettering look like it was professionally paint stenciled on.
That gray box in the power supply may be a filter choke. If it has two terminals on top, it probably is. Where is it in the schematic?
BTW, if you like looking over homebrew rigs, here's a project of mine from 2 years ago.  It's a plate modulated 4-1000A rig. It is finished and currently works very FB after getting the last of any bugs out...  
Stick with your 813 linear project. It is a good level to start at and then maybe tackle a plate modulated rig next.  

Hello Tom,
I haven't tried those transparent sheets yet.  I think when it is time I will give those a try.  I have another project from some time ago that needs labels too, so maybe this will be the way go.

There was not any schematics given for this amp, but the gentleman did give me a book that had amp projects in it and he did say this amp project came from this book.....Now where did I put that book!

Thanks for the link to your "AM" project.  You do some nice work there. 
To do nice work, one has to have some patience's! 
I had taken a look at your link before this site went down.  I was able to enlarge your pics, but now I cannot. 
There must be some more site issues here.  But I am sure we are all glad the site is back!

But anyway Tom, very nice work.  I really enjoy looking at other people's projects and learning new ideas from them.
In another post I mentioned I am basically an appliance operator, but I am comparing myself to everyone here.  I have built some small devices and such and I am not scared to jump in at anytime to learn. 

This is a great site to come and learn from that is for sure!

Thank you Tom.


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Posts: 4

« Reply #51 on: January 31, 2017, 03:38:40 PM »

Good inputs here! Appreciated the advice about derating a SSB GG linear for AM drive/service! Tubes really do take a beating just doing a carrier in this application. The idea of plate modulating an tube in RF Class C service drives me to the data sheets which of course consider the plate dissipation of the tube. I plan to do a 304TH/TL Class C plate modulated by a pair of 4-125A's in Class AB2. I hope to realize 750W carrier and 100% modulation. Plate on the mod will be 3KV and on the deck will be 2500VDC. Transformer is Signal Corp 7700VCT at 1 AMP!! Will do FW ...not bridge...and use variac to bring down the mod voltage. I can't do same 3KV on the deck as the mod sec Z is 8000 ohms. Need lower vdc and higher current to get that Z...and still have a carrier that can be 100% by the mod. You can see the need to 'jiggle' the RF deck to properly load the mod transformer. It is true the mod transformer can likely do margins of maybe 2:1 but I don't want to deal with possible distortion or clipping low/high end audio response due to improper loading of mod xfrm. Love the triodes in Class C for AM plate mod service! No screen. Maybe neutralization...but that screen supply is more parts that I can't well find these days. BTW: I even think I will do no choke input on the ps...using solid state. Just do high cap filtering. An even bigger AM rig will be a pair of 833A's modulating a pair. Now we are talking baby!!
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