GS-35's with Chimney's

[W1IA]

http://home.comcast.net/~w1ia/new_page_8.htm
Power supply finished!

Linear chassis with GS-35's with the Chimney's installed.
Tomorrow we fabricate clips to hold chimney's.

Brent
W1IA

[KX5JT]

Brett... that is a work of art!  Is your idea to use the Flex radio w/ it?  I can't wait to hear that signal.  It's sure going have some authority!

[W1IA]

Brett... that is a work of art!  Is your idea to use the Flex radio w/ it?  I can't wait to hear that signal.  It's sure going have some authority!

It will see service in the DX window on 75...I plan on using it for AM if I can muster up a decent driver. Flex is too pricey, might have a lead on a TS-440 that I can hot rod.
I need to do a rebuild on the 20 fet E-rig so this will fill the void. It will run about the same power as the E-rig AM service...that is if the plate iron holds up? I got 5KV at 1.5 amps available so it should do the job; otherwise I'll roll in a bigger chunk of iron....2 amps ccs would be more fitting for those beasts. Each pupe can pull 1.4 amps plate current. My bottle neck is the driver circuit...100 watts rms or 200 watts pep.
Just as well. Will keep me from temptation.

Brent
W1IA

[KX5JT]

Well Brent, not sure why I typed Brett, sorry about that.  I thought you HAD a flex already, but I was obviously thinking of someone else.  Whatever you use to drive it will certainly be fantastic. 

I wish I had some machine shop skills.... I'm thinking of taking a course at the local tech college just to gain some knowledge and access to the shop.  I'll have to see if they have morning classes that I could squeeze in after my night shifts.   

[WA1GFZ]

Ah just hot rod a viking 2 as a driver.
Man I hope you are out there raking Mark's lawn.

[W1IA]

Ah just hot rod a viking 2 as a driver.
Man I hope you are out there raking Mark's lawn.

He has taught me well Grasshopper! Much fun to work with.
Were still a month and a half away from testing minus paint. Thinking about throwing together a 2 fet e-rig to drive it? I have the H modulator collecting dust now days.
Mine as well put it to use.

[W9GT]

Cool amplifier, in the making, there Brent!  I thought about building up a three holer using GU-74b/ 4CX800A Russian tubes, but decided to just rebuild my existing 4CX1000A with some G3SEK "tetrode" boards for the control and screen supply chores.  I would still like to play with some GS-35s.  I understand that they put on a light show when you feed them lots-o-power.  Sounds neat!  Have fun!

73,  Jack, W9GT

[K1JJ]

The sheep here in CT are even more scared than before, Brentina.  

BTW, where's the beef?  (C1)  Are you gonna add a vacuum variable?     I take it C2 is the air variable?  Or is that C1 and C2 is below the chassis?

I can't see the roller inductor well enuff to molest it, but hope it will be strapping enuff to handle that load at full power. I've had several linears I've built that started out as hi-hi FB roller inductor tanks - but alas - a smokey month later there was a big 3/8 inch copper tubing coil and bandswitch in there...  

You guys are doing a nice job. Keep at it slow and steady.

T

[W1IA]

The sheep here in CT are even more scared than before, Brentina.  

BTW, where's the beef?  (C1)  Are you gonna add a vacuum variable?     I take it C2 is the air variable?  Or is that C1 and C2 is below the chassis?

I can't see the roller inductor well enuff to molest it, but hope it will be strapping enuff to handle that load at full power. I've had several linears I've built that started out as hi-hi FB roller inductor tanks - but alas - a smokey month later there was a big 3/8 inch copper tubing coil and bandswitch in there...  

You guys are doing a nice job. Keep at it slow and steady.

T

The big Jennings cap is not shown. Will be mounted above the loading cap. Plan on using ball drive reduction and chain or belt to allow for centering the turns counters.
As far as the roller-ducter...were not sure if will hold up? As long as not tweaking under full load should survive...its fairly heavy duty. I may have to consider band switch if we have a melt-down.

I assembled the blower and tube assembly to run back pressure test on the sockets.
Mark checked with manometer and measured only .5 inches water column. We calculate aprox. 160 plus cfm for the pair. It had a very acceptable noise level. No whistling or rattle...just a subtle rush of high volume air.

 Also resonated the plate choke and found it resonant at 28.044 mhz...bummer. Need to wrap my own or find a better choke.

[K1JJ]

"Also resonated the plate choke and found it resonant at 28.044 mhz...bummer. Need to wrap my own or find a better choke."

I always wind my own...  But did you check its resonace IN circuit with all the external influences like the tube, bypass cap, pi network and stray coupling?  As I understand it, out of circuit tests can be off.  So after the extra capacitance is added in, maybe it's series resonant way down in the good buddy band?  But that may be a problem too, depending on your interests...

How much C is the C2 loading cap?  Use the power formula at 50 ohms  X2 to give you a reasonable plate spacing.   Maybe consider a look on eBay for a $125 5KV  2,000 pf vac variable for C2 instead.

Every roller inductor I've used for QRO eventually developed hot spots. I even tuned them with RF power off. So hope the contact area is huge on that one.

Chuck always used to work me over about my proposed amps and it helped me save lots of time. Hopefully I can do the same for you if you like the heat...      But hopefully everything will fire up and perform flawlessly.

A few CT sheep jumped off the cliff here today. It must be getting close to show time.

T

[WA1GFZ]

I sold Gary INR the same inductor that he used in his dual 4-400 rig that was exported. The good thing is you have way too much inductance so a switch and coil should fit when you cook it. You are going to need a good 2000 pf of loading cap for entry level QRO on 75 and only 7 or 8 uh inductance plate tune will be 300 to 400 pf. L goes up and C down as you QRP.

[W1IA]

I sold Gary INR the same inductor that he used in his dual 4-400 rig that was exported. The good thing is you have way too much inductance so a switch and coil should fit when you cook it. You are going to need a good 2000 pf of loading cap for entry level QRO on 75 and only 7 or 8 uh inductance plate tune will be 300 to 400 pf. L goes up and C down as you QRP.

I have to agree (Frank and Tom); Mark and I discussed the roller...maybe will change to tapped tank and be safe. I got 5-1000 pf 10kv jennings for C1, C2 is 2000 volts spacing but need to double check value.

[W1IA]

"Also resonated the plate choke and found it resonant at 28.044 mhz...bummer. Need to wrap my own or find a better choke."

I always wind my own...  But did you check its resonace IN circuit with all the external influences like the tube, bypass cap, pi network and stray coupling?  As I understand it, out of circuit tests can be off.  So after the extra capacitance is added in, maybe it's series resonant way down in the good buddy band?  But that may be a problem too, depending on your interests...

How much C is the C2 loading cap?  Use the power formula at 50 ohms  X2 to give you a reasonable plate spacing.   Maybe consider a look on eBay for a $125 5KV  2,000 pf vac variable for C2 instead.

Every roller inductor I've used for QRO eventually developed hot spots. I even tuned them with RF power off. So hope the contact area is huge on that one.

Chuck always used to work me over about my proposed amps and it helped me save lots of time. Hopefully I can do the same for you if you like the heat...      But hopefully everything will fire up and perform flawlessly.

A few CT sheep jumped off the cliff here today. It must be getting close to show time.

T

Baaaa! Here little SHEEP!

I may take your advice and switch to vac cap for C2 Mr. Vu
I will look for a band switch to do the job and bail on the roller....funny part is there is a roll of copper tubing ready to go for zee tank. 

[K1JJ]

Good going, Tina. You've probably saved yourself as a lot of time and trouble already.  At least the C2 and tank coil will not be the weak points to be your limiting factor anymore.

You want an amp that just keeps going and going as you increase drive - until you run into saturation... the filaments just can't supply any more emission power...   You will get to that point more quickly with a vac var C2 and big band switched tank coil. (BIG bandswitch with WIDE spacing between contacts)   Heck, Chuck once told me, "A World Class Amplifier uses plug-in coils."  I did that for a few years then went back to the bandswitch. The plug-ins are definately better, but more work to row around the bands.

You will also need to wind your own plate choke. Start with a  16" long, 1" Lexan or Teflon core and wind on #26 or #28 insulated wire.  Don't worry about resonances. It's like hitting the lottery to actually have a problem in the narrow ham bands. I haven't had one occur since 1972.   If you are unlucky and it fries, big deal - just wind another one with more or less wire. Really a simple deal.

T

[W2VW]

Resonant plate chokes have a way of automatically making themselves non-resonant.

[WA1GFZ]

I use model 85 switch with 4 contacts in parallel.
I homebrewed one with dual contacts on each wafer and dual wipers.
4CX3000A never hurt it to 10 meters. Tank coil 3/8 copper with 10 mils of silver.