New 160 meter GS-35B shack amplifier..

[VK3ZL]

Well, I started on this new amplifier last Monday..I will take progress pics of this project as it takes shape..I had all the components on hand so I am able to get right into it...These first four pictures are the partial assembled case and most of the major RF output components..I have a metal work plumbing shop in Hamilton 30 miles East of here..Run by a couple of tradesmen they make air condition ducting, plumbing and water tanks and most metal work fabrications...I get them to cut all my panels from aluminum these days as they have the right machinery to do a professional job..Each case costs me about $50 all up..

I bring all the panels home and assemble an amplifier case using 12mm aluminum angle, copious pop rivets and heaps of patience..I cut all major holes for fans, meters, capacitors etc before final assembly...I etch all the internal panels in a caustic soda bath which gives them a neat silky finish which looks good and is easy to clean of finger marks etc..One must be careful not to scratch the surface..I don't have a large enough container to etch the main U shaped case frame..

The rest of the pics show the Pi network components for the RF deck..I hand make the coil using 12 gauge hardened copper wire which is polished then given a few coats of clear lacquer to prevent tarnish..This inductor is 23 micro henries and I will have to take off 2 or 3 turns once I set the network up..The vacuum variable capacitor is a new one purchased from Ukraine, $105..This is 250pf-5kv..The yellow doorknob is a 330pf 20kv shunt..I am using a salvaged 800pf air variable loading cap from an old Heathkit and this is shunted with a Russian 2200pf 6kv doorknob..The coaxial relay for the output is a 75 ohm Russian unit...These relays cost $25 from Ukraine and will withstand over 2kw at VHF..

Last two pics are the GS-35B Russian triode..This weighs 6 pounds, has a 1500 watt anode dissipation and 26 watt grid dissipation...I milled the grid mounting socket from a block of 1/2 inch aluminum plate and turned the hole for the tube on my lathe.Note the step in the socket where the tube grid fits...The tube grid is a fine fit into the socket and held in place with two "keepers"..

That's all to date...I will post another few progress pics tomorrow evening...As usual I am enjoying this job even though I do occasionally issue a few profanities when something isn't right...

Bob..VK3ZL..

[KK4AMI]

Well, I started on this new amplifier last Monday..I will take progress pics of this project as it takes shape..I had all the components on hand so I am able to get right into it...These first four pictures are the partial assembled case and most of the major RF output components..I have a metal work plumbing shop in Hamilton 30 miles East of here..Run by a couple of tradesmen they make air condition ducting, plumbing and water tanks and most metal work fabrications...I get them to cut all my panels from aluminum these days as they have the right machinery to do a professional job..Each case costs me about $50 all up..

Between all the metal work and rose gardening, you must not have an open patch of skin on your hands that isn't scars.

I bring all the panels home and assemble an amplifier case using 12mm aluminum angle, copious pop rivets and heaps of patience..I cut all major holes for fans, meters, capacitors etc before final assembly...I etch all the internal panels in a caustic soda bath which gives them a neat silky finish which looks good and is easy to clean of finger marks etc..One must be careful not to scratch the surface..I don't have a large enough container to etch the main U shaped case frame..

The rest of the pics show the Pi network components for the RF deck..I hand make the coil using 12 gauge hardened copper wire which is polished then given a few coats of clear lacquer to prevent tarnish..This inductor is 23 micro henries and I will have to take off 2 or 3 turns once I set the network up..The vacuum variable capacitor is a new one purchased from Ukraine, $105..This is 250pf-5kv..The yellow doorknob is a 330pf 20kv shunt..I am using a salvaged 800pf air variable loading cap from an old Heathkit and this is shunted with a Russian 2200pf 6kv doorknob..The coaxial relay for the output is a 75 ohm Russian unit...These relays cost $25 from Ukraine and will withstand over 2kw at VHF..

Last two pics are the GS-35B Russian triode..This weighs 6 pounds, has a 1500 watt anode dissipation and 26 watt grid dissipation...I milled the grid mounting socket from a block of 1/2 inch aluminum plate and turned the hole for the tube on my lathe.Note the step in the socket where the tube grid fits...The tube grid is a fine fit into the socket and held in place with two "keepers"..

That's all to date...I will post another few progress pics tomorrow evening...As usual I am enjoying this job even though I do occasionally issue a few profanities when something isn't right...

Bob..VK3ZL..

Between all the high voltage, metal work and rose gardening, you must not have an open patch of skin on your hands that isn't scars.

[K7SGJ]

I'm anxious to see the finished unit. If you ever want to hear how it sounds on the air, just send it to me.

[kb2vxa]

Nice driver stage, I can't wait to see the final.

[VK3ZL]

Well, got a little more done today..I etched up some simple circuit boards for the Bias cut off and Bias board protection..Also a simple Glitch resistor board that goes into the HT line and a Step Start resistor board..Pics show the finished boards..

I also completed the installation of the Pi output network..It all fits snuggly and is resonant through the band..I am just making the amplifier front panel..This takes time and patience..The layout has to be functional and presentable to look at..Also the top and bottom aluminum trims, 12mm square, has to be attached with a 2mm spacing at the top and bottom to accommodate the flush fitting covers..

I have had a few emails asking how I fit the 12mm aluminum angle..I took a pic of one corner while I was working..In this case the angle has to fit 2mm below the sides of the box so that the top cover is flush when fitted..I pre drill the box then cut the angle to size and using small clamps drill and fasten the angle to the inside..I cut all the angle with a hacksaw in the vice and trim it to an exact fit using a file..Works every time, or nearly..:chin:

BTW the fan is a 240 volt all metal 6 inch Papst rated at 290cfm..I like these particular fans as the metal blades are heavy and don't lose speed under load.. This produces more than enough air to cool this tube even at 1800 watts output..I must measure the back pressure..I have a manometer in a drawer somewhere..

Bob..VK3ZL..

[mw0uzo]

Looks great, keep up the updates :)

[K7SGJ]

Well, got a little more done today..I etched up some simple circuit boards for the Bias cut off and Bias board protection..Also a simple Glitch resistor board that goes into the HT line and a Step Start resistor board..Pics show the finished boards..

I also completed the installation of the Pi output network..It all fits snuggly and is resonant through the band..I am just making the amplifier front panel..This takes time and patience..The layout has to be functional and presentable to look at..Also the top and bottom aluminum trims, 12mm square, has to be attached with a 2mm spacing at the top and bottom to accommodate the flush fitting covers..

I have had a few emails asking how I fit the 12mm aluminum angle..I took a pic of one corner while I was working..In this case the angle has to fit 2mm below the sides of the box so that the top cover is flush when fitted..I pre drill the box then cut the angle to size and using small clamps drill and fasten the angle to the inside..I cut all the angle with a hacksaw in the vice and trim it to an exact fit using a file..Works every time, or nearly..:chin:

BTW the fan is a 240 volt all metal 6 inch Papst rated at 290cfm..I like these particular fans as the metal blades are heavy and don't lose speed under load.. This produces more than enough air to cool this tube even at 1800 watts output..I must measure the back pressure..I have a manometer in a drawer somewhere..

Bob..VK3ZL..

Looks great, keep up the updates :)

You two made me feel so guilty with all this home brew, design, building, and ham radio stuff in general, that I got inspired to build something. So, today, I built a fuse tester that runs on 110 volts. The problem is I can't seem to get the fuses out of the test circuit fast enough. I guess it really doesn't matter much as I can't see shit from all the bright flashes, anyway.

[mw0uzo]

You two made me feel so guilty with all this home brew, design, building, and ham radio stuff in general, that I got inspired to build something. So, today, I built a fuse tester that runs on 110 volts. The problem is I can't seem to get the fuses out of the test circuit fast enough. I guess it really doesn't matter much as I can't see shit from all the bright flashes, anyway.

Heh.

I can recommend this should you want to build something
http://www.radio-kits.co.uk/mkars80page.html
Great kit, good price, works very well. The huff-puff VFO stabiliser works properly too, so no drifting around. I do all my 80m stuff on it either barefoot or connected to the amp. Get the case and knob options for a complete kit and also this hand mic, rewiring the inside to suit. :)
http://www.ebay.co.uk/itm/Hand-Shoul...item3f16fb8025

Don't connect 110V to it though ;)

[VK3ZL]

Saturday..I have been on this job for 6 days now..I did my calculations for the tank output circuit yesterday and made up a new coil...Plate resistance will be in the vicinity of 1500-1800 ohms...This requires a coil around 14uh to 17uh for a circuit Q of 12..I always find that the calculated formula to actual operating conditions varies and proper adjustment of the Pi network can be finalised under power...However it will be within the ballpark..I spent most of yesterday fabricating the amplifier front panel and gave it the final coats of paint last night...I used Metallic Charcoal on this job..It has a fine mica fleck and looks quite good...I lettered up the panel this morning and gave it two coats of finishing lacquer then placed the meters and switches etc..

I am now working on the Cathode compartment and will have it completed tomorrow...Then I will be able to start on the wiring up..

Only 3 pics today..My photography isn't all that good...Two of the completed front panel and the completed Pi network with 17uh coil..

Bob..VK3ZL..

[VK3ZL]

Sunday....I worked on the Cathode compartment today..This has a Pi input network, filament choke and Bias feed choke..The Pi input has a Q of 2 and is adjustable with a slug tuned coil for 1-1 drive vswr..I use a simple 24 volt cradle relay for changeover directly connected to the input coax connector...The toroidal filament transformer delivers 12.6 volts...It is a bit large for the job, 8 amps where I only need 4 amps but it's one I had on hand...The HT passes through the Cathode compartment via ceramic and Delrin feedthrough's...The WW resistor is a 30 watt 22 ohm Glitch resistor in the HT line to protect the HT supply in case of tube flash over..

I am now to the wiring up stage and will work on this over the next couple of days..I have the rectifier stack for the HT completed ready to install.. So not much more to do...

Pics are the Cathode compartment..

Bob''VK3ZL..