The AM Forum

...HI FROM TIM...I WOULD LIKE TO INCREASE MY OUTPUT ON 160,AND WOULD LIKE SOME INPUT AS TO WHAT AMP I MIGHT BUILD FER 160AM...I WOULD LIKE TO BE IN THE AREA OF 300 WATTS OUTPUT...IDEAS?....SK..

4-1000A in GG would be perfect at 300 watts.

Pair of 3-500's or even a pair of 4-400's triode connected or one of those Russian triodes if you don't mind forcing air past it. What do you have to play with? Got a power supply? What volts & amps can you deliver? Do you like the glow or "Tubes with Handles"?

...I'VE GOT NOTHING GOING AS YET...READ AN ARTICLE FROM '61 QST,PAIR OF 813s IN G-G. THAT'S WHAT GOT ME THINKING ABT THIS PROJECT...I'M TOO PW ON 160....TIM...SK...

I agree. Thats what I use here. Keep in mind the toob cost. New 4x1 can be as much as 800 to 1000 bucks.
Also the toob likes about 4 to 5 KV.

..c'mon..there must be a more reasonable way to build an amp fer 160...if i built a single 813 transmitter,with plate mod that is gonna give me 200-240watts..out..why soooo much fer an amp.?..sk..

An 813 as an amplifier will not give u much poop........plate modulated is a different story. He was asking about an amp I believe.

I assume, as well as the other responders that you are planning on a linear amp and not a class C amp to modulate. If that is the case, the effeciency is quiet low with AM. To get 300 watts output and have some headroom, you will need a larger amp than you would expect. For example, you couldn't really get 300 watts of AM out of a Heathkit SB-220 with it's pair of 3-500Z's and light duty PS.

Drake L4B kicks butt if you want a commerical amp with BAs.

Dave said:
Frank said:
The only problem is neither will do 160M without some extensive modifications.

I would agree that a 4-1000A in linear grounded grid is a great way to start out. Build a linear first, then tackle the plate modulated rig, like 813's modulated by 813's.

 The 4X1 tetrode is a unique tube - such that normally, tetrodes are not good performers in GG. But the 4X1 is.  It really is a 2KW plate dis tube with enuff air, though speced at 1KW..

Read this Eimac engineering letter that talks about the 4X1 in GG with examples at various voltages. A rare letter about special 4X1 applications.  Notice the input impedance is > 100 ohms, needing matching for a 50 ohm 1:1 swr.

Every ham worth his salt should have this letter framed on the wall. Or at least saved to his hard drive... ;D ;D


Copy and paste into your browser, otherwise will not link:

http://wc6w.50webs.com/wc6wamps/popp.html?eimac1K.jpg

...OK... THIS IS THE KIND OF INPUT I WAS LOOKING FOR...THE DEAL IS,160 IS ONE OF MY FAVOURITE BANDS,AND AS OF NOW I'M PW...I'VE  BEEN THINKING OF ALL KINDS OF ROUTES TO TAKES,AND AT PRESENT MY EXCITER IS A VIKING 2...THOUGHT ABOUT CLASS E AMPS,ALL KINDS OF STUFF. BUT,THAT IS WHAT MAKES THIS HOBBY GREAT. GOOD INPUT FROM GUYS,WHO REALLY WANT TO HELP,AND NO INPUT FROM CREDIT CARD,DIPOLE-IN-A-BAG GUYS...REAL HAM RADIO...TIM...SK..

Tim, to really make it simple, start out with making it strickly for 160. Then, add bandswitching as you desire. It would cut down on your tank circuit C, (you could use some fixed C with a smaller variable), and a straight coil. I like the idea of using one of those Russian GS-35B's. Cheap and give you damn near the same amount of power out as an 8877. By the way, did I happen to mention that they are cheap :o

I agree Mike....

I don't want to sound like a salemen for GS-35B's but they sure look like a lot of bang for the buck...

I'm really tempted to build a linear using a pair of them  ::) with a well designed power supply, that would be a real "window washer" caw mawn!!  ;D ;D.. Like Tom, I was going to build a YC-156 amp but the surplus source for those may have dried up.  :'(

Tim, check out this link =http://home.comcast.net/%7Ewb8wju/