Finished up assembling the coil contact slider.  Disassembled the initial screwdriver build and used componets from that on the build.  Used the 12v gearmotor, 400mm screw, one of the Keystone 209 contacts & wire on the new build.  The switch & wiring are also reused.  

The screw is now gear driven & the contact carrier has an M6 nut that rides up and down.  The allthread screw is constrained by 608 bearings at the top & bottom of the guide. A cap on the screw keeps it from passing through the top bearing.  The gears were built in OpenSCAD, then imported & modified in Fusion 360.

A tripod base will be attached, but is not in the pictures below.

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Mute or turn audio down to avoid listening to the motor whine.

Damn...that makes some noise.

Cool as can be though!

Got digital modes going on the Windows machine for the Yaesu 710……. But not the linux machine. Might need to do some updates or something.

Portable Zero rails came in the mail, so I am ready to throw it in a backpack and head out somewhere.

After playing wth the slider build, went back & genned up a more optimal layout.  All components can print on a 300mm capacity machine including a shorter but larger diameter coil form. Still provides a bit over 100uH.   Would use a 300mm allthread M6 instead of 400mm.    Markers on the slider guide tower & a pointer on the slider to help mapping to the bands.  Tripod leg connections printed directly on the base  Would wire the sliding contact to the top coil termination point for easier/neater cable run.  

Overall size (without legs) is roughly 12.75" tall, 8.5" long.  May print/build this one, may not ...

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components colorized

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@Shootindave
I run FLDIGI and FLRIG on Linux Mint, they're both in the repository so no worries about setup.
73,
Rob

10 students through a rainy tower auth class.  Mostly 911/OEM techs, fire rescue, LMR, and telecom/network guys.  Couple hams in the group too.


Gearsplosion in the hotel room, dry out as much as I can, then out to dinner.


Go through powerpoints and course objectives for day 2.  It's been a while since I've taught a tower class, and even longer since I've done an advanced rescue day.  Worked through some knots I don't work with regularly, and setting up a retrieveable anchor before I do it in front of students.


In the classroom we talk about ropes, and identification/serialization of ropes with a rope log and recordkeeping.  Inside most ropes is a tracer printed with manufacturer, lot number, date, specs, etc.  I didn't have a good photo of that.  Other instructor had a rope with a frayed end, and that tracer stickin out the tail.  Now I have a photo of the tracer.


Much nicer weather today, still had a few light rainshowers.  Climbed up one leg to do some housekeeping/rope management and safety watch during one student's traverse across the tower face.


Advanced day is a lot more fun.  I throw a scenario at the students and let them figure out how to set it up.  Start with "Lift this heavy thing up the tower.  Basic safety protocols apply - no hoisting from under the load, maintain progress capture, and use mechanical advantage where justified."


Road next to the tower was pretty busy.  About every 3rd car would slow down and gawk at us.  Sheriff even drove by and gave us a thumbs-up.


Last exercise of the day, rig up a skate block and bring someone off of and away from the tower.
One student mentioned "I can't think of a time where i'd ever use this.  It seems complicated."  My response to questions like that is a "toolbox approach" - You might be able to spin a filter off your truck with a pair of channelocks you already have, but is it the right tool for the job?  Is there something else that's safer, easier, or faster?  We're adding this setup as a tool in your toolbox to do your job safer, faster, or easier.  Then a quick story about the time I was tower crew on an AM broadcast tower, where the tower's electrically hot and there's a lot of equipment at the base of the tower.  How do I maintain electrical isolation between my patient and ground?  How do I avoid having to shoot the tiny window around the equipment at the base, or the fence at the bottom?  The answer is a skate block like this.  You might not need it often, but there's places where it's justified.
Off the tower and over the fence we go!


As we were packing up equipment and discussing course-close, one of the students told me "I wasn't looking forward to this training, but you guys made it awesome."  
Dry out gear overnight, pack up in the morning and head home.

Good Lord man. That is amazing. I can't imagine what it costs.

Linux works fine on my Yaesu 891. Just was giving me troubles with the new 710 for some reason. I will have time later next week to make sure everything is updated and then go from there,

That is pretty cool. I am an avid deer hunter and I hunt more public land now than I do private. I converted to a saddle some years back and never climbed before.  In fact I do not like heights. Took me a while to get comfortable.  I climb with tree sticks and use a 40’ line of Sterling 8mm rope.  I use a mad rock safe guard on my bridge and it stays on the rest of the hunt. When I am done I drop the rope out of the tree and zip down the line pulling my sticks on the way down. Good equipment is not cheap. How often would you recommend replacing ropes? We use a girth hitch and delta ring around the tree. I inspect it before every hunt. Any signs of anything abnormal I usually replace it.

Getting ready to set a tower to 30-40 feet or so. I am may use my saddle for that with a 2 rope system to climb and come down          .

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Picked these up from a friend. Going to give 222 a shot. Plan is to use these rover as well with the X6100. Going to have to build a beam for the 222.

I have the AM-6154 that is pretty much ready to go for 222. I ordered a 2kw low pass filter for the Harris 2m amp and the beam is up.

Will have to get a TXCO PLL board from Demi to get the transverter GPS locked.

In the short term I have to build the new 2x22el antennas for 432 and a 12 el for 222. Not sure if they will be done before the June contest so I have a dual band Squalo coming.

I have been battling isssues on my 1296 station. Antenna has been up a long time and was never able to make contacts. Recently I changed the coax  from 1-1/4 to 1/2 super flex directly to the antenna. I was not able to hear anyone on the moon with my 55el and the local beacon I cannot hear. Got someone about 90 miles away this morning to jump on FT8 and they were +2 and I was -11 on their end. So the station is working well. All 4.5 watts to the 55el did the job. Bow time to find some really large helix to limit loss and get a low power amp until I can build an LDMOS pallet. Should have the DEMI preamp soon for it. Its amazing that a 40’ run of 1/2 hardline has 3.6db of loss. That is microwave for you.

I will post some updates when the Harris is online. The new LFA SWR is a bit high for now until I can get it tuned.

Right at $9k for 80 cells and 10 BMS.   Most of the other parts like cables and bus bars I was reusing so no additional expense but they were pricy the first time.  

I just finished the install and put several pics in the homestead forum if anyone is interested.

So I still have my SB220 project to complete.  I've got the final pieces of the puzzle, a series glitch resistor and a high voltage fuse.  I will install these soon.  

But for now, I have spent the last 3 days doing a huge overhaul of my ham shack room.  The way it was set up before, I didn't have a proper desk.  But the room is also used for storage.  I've been going through and prioritizing which things I can move to the attic, and which need to stay available for easier access.  

I've got some monitor risers on the way that should help organize the desk/table and help stack equipment while keeping it cool.

The plan is to have the amp, radios,  tuner and computer all on one desk, with some room for taking notes and charging HTs, etc while not being cluttered.

A gentleman in town is getting his tech license. I got him an older Kenwood 2m setup and we stole a 12V power supply from a scrapped piece of machinery. Tested everything last weekend, working great.

He wants to build a 2m antenna that will attach to an old arm on his roof that used to have a satellite dish.

I made myself a copper J pole for this exact application that I still use…….  But am wondering if there is something “better” like a copper slim jim we should make instead.

Any input?

@Shootindave
"J" poles and the like have skewed radiation patterns. Go with a regular ground plane or one of the higher gain verticals.
73,
Rob

Here is a jpole calculator, if that helps.
https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/american-version/

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Little qrp amp project

What you're doing is a lot different from what I do.  
8mm rope is fine, as long as it's rated (usually 22kN for that stuff, at least in the industrial/rescue world).  Rock climbing gear doesn't usually have the integrated safeties that industrial stuff has (Petzl ID has anti-panic, if you pull the descend lever past a certain point it locks out and stops you, and also has features for preventing falls if the rope is loaded incorrectly).  Also pay attention to the rope sizes the device can take, some will bite on 8mm but won't safely arrest a fall on it.  Rig everything high and tight to limit your fall factor.  

Rope inspection... feel the length of it for any hourglassing (hard-soft-hard spots), abrasion or fraying of the mantle/sheath, discoloration/uv-fading.  
Ropes have a natual D/d ratio, the radius the rope wants to bend at.  I'd roll through the rope looking at that D/d diameter and see if there's anywhere it's fucked up.
Wash the rope periodically... warm water and woolite's what I use.  Rope brush if you want to get fancy.

Might look into "retrieveable anchors".  

"Ah, there you are."


Ground crew was totally new, got the camera candycane assembled, mounts assembled, helped the ground guys out when they needed it.  Spent some time with them going through rigging, knots, what's going to happen once we're on the tower, etc.  First climber got started up the tower while I finished rigging everything and getting ethernet tools ready so I could climb with that cable.  Once the camera started moving up, I hooked the ether cable to my side and started climbing.


Got teh camera up and dogged off, assembled mounts to the tower and got the candycane hung.  The way we rigged it, made it easy to do some tricks to get the level damn near spot on.  Made that job easy.


Got the transtector installed, other climber cleaned up and connected that cable while I anchored, terminated, and snapped the test load onto the ether cable I brought up.  Radio'd down to the ground team to test the cable and once we got a pass, we'd finish up and start snapping cable mounts down the ladder.
About 10 min later... "Just hang out for a minute, we're having a connector class down here."


They had to reterm a few times to get a pass, but once they did it was back to work.  Wrap everything up tower-top, then send my bag down and have the crew swap out some tools.  Worked my way down the cable ladder securing the ether I brought up.  Other climber hung out where my anchor point was, and when I got to a good stopping point I'd have him break down the line and come down the step bolts, reset my anchor and continue working down the ladder.
Tower was busy, lots of obstructions to work around on the climb up, and a few areas were spicy with RF (Trunking control channels always TX, even with no traffic).  


Clean up the site, double-check everything in the shack, pile gear into my pickup, close doors/lock gates... finally outta here.

Man, every time you post images like this, I have to go take Acetazolamide.

I'm just way too acrophobic for a job like that. The view is fantastic, though.

@NAM

catching up on this thread... one thought might be that UHMWPE rope is slippery-er so might hold up for longer? Might be worth a try.

What the ham world needs is something like phillystran in very small sizes for antenna wire supports.  Phillystran for those who aren't familiar with it is aramid (kevlar) fiber rope with a polyethelene jacket as if it was coax.

Another idea if you can get to the area of the tree that's giving you trouble is to run your rope through a couple feet of polyethelene hose/tubing and position the hose against the tree, so that the rope moves within the tubing instead of directly on the tree.


Are those the ones from the Ukranian guy? I've thought about getting a 222 transverter to get on the band.

Yes unfortunately he is out of the game since his city is under Russian occupation. They are drifty tough. Going to have to use a PLL circuit with a 10mhz local oscillator with a reference in.

I've built one of these but never finished it because I didn't have time to sit down and make the circuit that handles band data for switching the LPF.  I still have the parts and info, just need the time and motivation.  But my 817 is so close to obsolete that it might jot be worth the bother.

I would just grab one of the ceramic band switches off amazon and use that for switching bands. Then you can get one of the decoder kits online and wire it to one of the band switch contacts. That way you have an auto switch position, and if you have any issue you can switch manually.

I have considered building one of the low power amps, but it is easier to just buy a micro pa50+ with auto band switching, filters installed, swr and thermal protection built in. It can also be used as a power/swr meter.

Ah that's a good idea, thanks!  Having a manual option would make it useful with other radios as well.

There might be a reason I post those "looking-down" pics in every post
Some recent jobs.

Big TV in the radio shop, we'd rotate through camera feeds, NMS/system status, weather radar, whatever we needed/wanted up.  In NMS, one of the sites microwave was highlighted bright red for a few months.  It's a failover path, sites are all connected via fiber, but still nice to have the redundancy.
I installed that camera we're watching last fall.


Was going to fix that radio with the camera install last week, but between the late start and on-the-job training we had to do, we ran outta time before that got done.  I stopped by the shop to pick up one of the kids who needs more experience around towers, and met two other coworkers out there at the site.  Quick run-down of the steps I'm going to do to troubleshoot and repair this problem, and what I need done on the ground to facilitate that.  
The dish in question is one on the bottom of the pipe-to-pipe.
Notice that:
   - Step bolts stop at the first flange, and don't continue up the tower on that leg
   - The pipe-to-pipe stands those dishes off the tower leg about 3ft
   - If I crack that mount loose, there's nothing stopping that dish from dropping off the tower and crashing into the ground
   - Face width of the tower is about 20 feet, the X-braces are about 7ft apart
   - There is jack shit to stand on to access this dish, and
   - There is no bucket truck in sight.
So yeah, accessing this is going to be the most difficult part of the job.


Ended up climbing the leg with the cable climb, overclimbing the dish, traversing across the face of the tower (sketchy, btw, but still maintained 100% tie-off and <1 fall factors ), setting a rope and descending down the leg without step bolts to the level of the dish.  Was able to use positioning to pull me away from the tower towards the dish for easier access.  It's shit like this where I really appreciate having a rope access harness vs. something more tower oriented.
Yoinked the cable out of the dish (fuck you, ubiquiti, for not tethering the cover to the radio ) and snapped my PoE tester on the end... nothing.
Cut the ziptie holding the transtector shut, and immediately located the fault.  I'm glad I didn't have to swap the dish+radio, but I was kind of hoping I'd get the kid some experience with rigging.
Fixed the problem and got good PoE to my tester.


Drop down on my descender a little bit, hook my ankles around the tower leg, and do some yoga to get to where I could see the connectors and status LEDs.  Shoved the connector into the radio, and watch the status LEDs do their thing.


Link came up, looked good... got pulled into the shack to troubleshoot some connectivity issues to the camera I installed last week.  Our ground team needs more practice terminating cat5's... couple pins weren't making good contact.  Cut their end off, trimmed/prepped/crimped an end and everything came up nicely.  Troubleshot that to a routing issue - which means I don't have to climb to the top.  Climbed the 30ft or so and traversed the face again to retrieve my ropes/anchors.
Cleaned up all my gear, threw it back into gear bags, locked doors/gates and "Sayonara, shitnuts."  Nice to see this job in the rearview.


"Hey, you're pretty good with this microwave thing.  We've been having a problem with another link at the police station, see if you can fix that too."
Also fix'd.


Another tower install/microwave build out in the plains.  60ft tower.  Plan out the hardware, build mounts on the ground, climb to the top and set a vertical lifeline and haul line for parts.
First time i'd met one of the other climbers.  Small damn world, he used to be an instructor for the company I teach tower rescue with now.  


Get the horizontal mounts installed and level (5ft wide centered on the face of the tower), haul up the vertical pipes (10ft long) and plumb those, get dishes up the tower and mounted to verticals, while I worked on pulling ether cables and testing/securing those.


Got more done that I expected to, glad all the dishes are up and secured, now it's just installing radios and peaking the shots.


"All set?" "All set."  Ran up the tower to drop haul line and lifeline.  Shots look good from here...


2ft and 3ft dishes, parallel paths.  I'll probably be back here in the next few weeks to get these dishes peaked and links online at full capacity.

Indeed, i am going to do this for my 2kw LDMOS build. The idea is to have a band decoder to operate it, but in case of failure to have a manual band switch. Any cheap switch would work really especially with relays. I used this switch:




This is being used with my Bird Line sections. It comes into my control box and I switch the different line sections into a bird 43 peak kit with a 2x-5x switch. I can have up to 6 line sections on 1 meter. The quality seems decent for the cost.

ETA I may also plan to have the second pole act as a standby transmit switch for my LDMOS amps or to power on the supply mosfet to power on the amp. But I am not sure how I want to do it yet.

Interesting approach - I may give some thought to doing something similar in the future.

I've been using individual meters with my Bird thruline couplers, and that gets very expensive very quickly, even with aftermarket meters (not to mention my eye-wateringly-expensive collection of Bird 43 elements).

What I have been considering doing is using much cheaper generic meters with a homemade normal/peak-reading, 1x/2x/5x multiplier circuit - and then replacing the normal scale (0 - 50 ua or 100 ua or whatever) with a DIY printed wattmeter scale. I don't have to stick to a 30 ua fullscale meter movement due to having an op amp or an instrumentation amplifier driving the meter.

But for now, here is yesterday's project, a quickly-thrown-together, work-in-progress-but-almost-finished dual line section wattmeter, with the parts mounted on a 1/4-inch thick heavy card/paper board - so for lack of a better name I'm calling it my "Cardbird 43" wattmeter...

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I picked up a 30ma meter from Ebay. Its seems accurate enough. I made the mistake of buying a different preak kit though and its not perfect like the one in my bird meter. Attached File


This is FT8 on 6m. Its a 500w bird slug on 2x so right about 800 watts. Currently I have 2 line sections on it. The 6m one and one for 2m that has a 1kw slug for my other harris amp. Works well and for 39 bucks with an LED back light. You could do the same with a 2 slug line section and have reflect as well. Or have a SPDT switch and use the second pole of the band switch for reflect. The 2 com leads going into the switch for measuring reflect on either band. The possibilities are endless. I put 6 BNC ports and used RG-174 for the leads to the band switch and ganged the shield together at the BNC and switch that goes to the common ground as well.

ETA: the switches under the band switch is the peak kit. The left switch is peak on or off and the LED lights in peak reading. The right switch is center 1x up is 2x and down is 5x. Got rid of the 9v battery and run a dc-dc converter dropping 12v to 9v from the 12v 100a supply that is in the case. May give you some ideas to play with.

Having a common control center like that is a good idea.

I have not yet fully mapped out the ultimate configuration for my envisioned “DC to light” station of the future as I’m still assembling parts and pieces, of equipment and antennas and transverters and amps and SDRs and PCs. I expect that I will go through a bit of chaos first, as I still have much to learn and think about. But seeing how you have organized your setup is indeed helpful.

I did also get a pair of those rectangular aftermarket meters from eBay - I will probably use them with my dual-element line section with a 2500-watt 2-30 MHz slug (ouch - expensive) and a lower power one, for a dedicated HF unit for simultaneous forward and reverse monitoring.

Yes, the peak-reading circuitry needing a 9V battery has always been a weak point - so your solution of combining the rf metering with the power supply monitoring makes a lot of sense.

BTW, wonder if someone has designed a 3D print for a powerpole locking mechanism - I accidentally yanked my power cable out this afternoon, and would prefer to avoid that possibility in the future. Maybe wrapping with black tape will be good enough, though…

Yeah back when I was contemplating different ways to handle input band switching, it occurred to me that an extra switch position on a rotary switch could be used to put the amp in standby mode without cutting a new hole in the front panel.  In the case of my SB220 amp, I'd probably use the meter switch for this purpose.  

I'd have to find a switch with the same angle between the first three positions so it would line up with the markings on the face plate.  And just leave the 4th standby position blank or make an adhesive label.  And if I really felt like tinkering I could add a provision to change the meter backlight color to indicate standby rather than drilling for a lamp or LED.

I think originally power poles were intended to be locked together with a roll pin in the hole to keep them from sliding apart.  I bet if you can find a narrow enough zip tie you could thread it through both holes and snug it up.

Weed eater string?

The usual retention clip or zip tie approaches that I've seen work well for inline powerpole connections, but will not work in my situation.

I have an Astron power supply that I use with my Anan 8000DLE. The powerpole connectors on the front panel of the Astron do not expose the hole that would be used to tie together a pair of inline connectors.

Perhaps I could rig something up using the mounting screw visible in the photo.

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Comparing that with retention clips or with the zip tie method shown (for example) at https://www.nj2x.com/2012/10/how-to-lock-together-ander-powerpole.html?m=1 you can see that only the cable-side hole is accessible - the hole in the connectors mounted to the Astron front panel is not.

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So earlier this week I was working a huge opening on 6m. Running for about 2 hours @800w with the Harris. Herd a thump and the amp kicked into protection mode and a disticnt smell started. Kicked the amp off and cranked the radio from 15w of drive to 100w and kept working stations.

Tore the amp down and noticed some dark marks around a resistor for the bias feed on the amp control board. Pulled the board and the resistor values were good. Ended up pulling the power supply apart and nothing. Got around the low pass filter and caught the smell. Pulled the LPf out, it was mounted on its side and has perforated board for the PCB capacitors with a couple of SMD caps. Apparently it got so hot the solder began to flow through the board and bridge close enough to ground to arc over!  

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If you notice I forgot to clean the flux off the board. Also intended to reflow the solder on the RF pads but did not get to it. So I did clean the board up, and reflowed everything. Can see where it began to erode the board near the input. I now have 14.5k ohms from the RF path to ground. Needless to say amp works fine with it out of line. 3rd harmonics are a concern here, but built a coaxial stub for the VHF contest. Ordered a new filter board that is also rated for 2KW like the first board and the board I have for the 2m harris. This time I will be adding Fans to the enclosure to help cool the boards down. If you want to test equipment just run high power. You will find the weak link quick.

I have all my power cables secured with a zip tie that has a built in eyelet for a screw. Then I attach the eyelet to something to create a strain relief point.

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That is interesting - I've never encountered those "in the wild" - I will have to do some searching online...

Ah, yeah that's different.  I think you are on the right track with the screw.  Maybe a tiny "L" bracket that extends out far enough to put a hole above the hole in the connected plug, then drop a pin through both holes.

So after melting down the 6m LPF I decided to make some changes to the 2m LPF. This one is rated at 2kw + and uses teflon board and teflon coaxial capacitors. This picture was before cleaning it up. I used copper strips for the RF connection but may go back and use a section of RG400. But the heat was the biggest concern for me.

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Hoping the 24v fan will keep the LPF cool enough. I have a new LPF coming for the 6m amp and a second fan as well. I also picked up LDMOS 1.8-54mhz 1200w board. This will be the first of 2. I want to get the first pallet built and tested. Then add a second one for a 2500w HF amp that can limp along at legal limit.

This will have the Auto and manual band switching, touch screen controls and built in auto tuner. I will be building the heat spreaders and will be a combination of different parts with built in antenna switch as well controlled by a 7” touch screen.


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So that DX World board, I can't remember from when I was searching these a few weeks back, but is that the one made by the company in Greece?

I really wish there was a "one stop shop" for all the necessary components to build a complete amp, but it seemed like even the places that stocked the boards, transistors, LPF kits, etc were missing some components here or there.

I'd love to build a kit, but I don't want to have to plan out my own cabinet and work out details of where to locate things like the fans you're dealing with, etc.

For the LDMOS hf amplifier, I take it from the photo that it is this board (minus the LDMOS part)?

https://www.dxworld-e.com/product-page/ldmos-1-2kw-hf-linear-amplifier-board-1-8-54mhz

As for the melted low-pass filters, some musing out loud, about which I could be totally misguided.

I'm guessing from the photo that the low-pass filter topology is four inline sections of a series inductor each with a shunt capacitor, with the input at the left and the output at the right. But I'm not sure, both because I can't see everything in the photo, but also because I don't have a lot of experience with filter theory.

If that is indeed the case then, at the fundamental frequency (that is, at the 6-meter transmitter frequency), I'm thinking that the filter may look like a series inductor rather than a tuned circuit (or, perhaps better, as a set of tuned circuits with resonant frequencies far away from the fundamental frequency) - but maybe I'm misinterpreting something.

I've been wondering whether the internal heating is a direct result of the 'insertion loss' of the filter when handling high rf currents at the fundamental frequency (that is, due primarily to i-squared-R heating related to the Q factor of the inductors. But I'm also thinking that if my interpretation above is correct, then the inductive reactance of the series combination of those coils should have been chosen to be 'low' at the fundamental frequency, even though the series combination of those inductive reactances is additive - because you'd want the effect on the energy at the fundamental frequency to be minimized (and, ideally nil). So, if the inductive reactance of those coils is truly low at the fundamental frequency, then the Q factor Q=2 pi f L/R of those coils would likely be low at that frequency (after all, a straight-through thick copper strap would likely have a low inductive reactance even at 6 meters, and since we are not looking for resonance at the fundamental frequency, we don't care about Q or losses from low Q at that frequency (ignoring factors such as stray capacitance and skin effect).

Furthermore, what would be the expected rf current at the fundamental frequency with 2 KW into a 50 ohm resistive load? Less than 7 amps? (maybe it could be significantly higher in case there is a high VSWR?) But, maybe i-squared R heating at the fundamental frequency may not be the culprit here.

The place where the solder melted appears to be at the junction of two coils and a capacitor, at the third resonant circuit out of four, from the input at the left towards the output at the right.

I don't know what frequency each of those resonant circuits may be tuned to - but it leads me to wonder about at what frequency or frequencies the heating may be occurring. For example, I'm wondering whether the heating may be occurring primarily as a result of the energy occurring at some harmonic frequency or frequencies (that the filter is attempting to shunt to ground), and if so, which harmonic(s) that may be.

It has been a long time since I've given it any thought, so I had to look it up - but for a series-resonant LC circuit, the impedance will be minimized and the current will be maximized at the series resonant frequency. I'm wondering what that resonant frequency may be for that third LC section. Yes, there may very well be coupling to the other inductors and to the circuit board and to the case, but I wonder whether it might give a clue as to what harmonic frequency was to blame here.

Anyone who has a better grasp of the fundamentals involved here, feel free to chime in.

Of course, maybe I'm sliding this thread way, way too far away from its original intent.

I do not think so, its where we talk about projects and any insight is good. So the 3rd harmonic on the harris is the big one. At 1kw on a channel 2 harris operating at 50mhz its about 35 watts of power at 150mhz. On top of that I would imagine that the current flowing through also heats it up a bit. Couple that with running digital modes and it adds up.

The LPF above is for my 2m harris and is made by W6PQL. He mentions that at really high power that they need air. Now take the fact that most antenna are not going to be a 1.1:1 SWR and that is going to equate to more heat. My hopes is that the air will help.

The 6m board was made by a russian guy and looked really good. If you notice the lack of a lot of capacitors on the board. The pads and board has a certain capacitance to it and they use the design to keep part counts down. I am not sure if there is a carbon track in the board or a capacitor broke down. I may take the caps off the board and see what the resistance between the RF path does.

As far as the DX world board, he seems to have most of the parts to build a complete amp. My plan is to run his control with touch screen and maybe his LPF. I will be using some parts from W6PQL and some custom parts as well. I really want a 2500w amp with internal tuner, but that part seems to be the hard part. My plan is to build the case and components large enough to handle 2 pallets. Build it out as 1 pallet with internal tuner, then upgrade it later to 2 pallets with external tuner. The reason I got the board without the device, there are a lot of knock offs out there. I would rather purchase the device from Mouser and know I got a legit one. Should be a fun project. At least it will double my current output and get me on the Warc bands as well.

ETA: The insertion loss measurements were low on the VNA originally. But its hard to say. Use to hollow state gear for power. I think when it comes to high power Coaxial stubs might be the ticket. One of the reasons I went with a LPF for 2M that is rated for 2kw+. The 6m filter was also rated for 2KW, so I am suspecting the small metal box just caused far too much heat. So fans are the next step. Also keep in mind I did not clean the flux off. And that may have contributed to an RF path that ultimately caused the failure.

A wise old ham once told me that every station has a weak link. And as the power and frequency goes up you will find it. Lol

Yeah. My weak link was the effn traps in my MA5B trapped 5 band yagi.  1500 watts rated my arse. I would recommend no more than 350 watts of any digital mode. Which would be close to my rule of take a power rating of any RF device and divide by 4.  Things are "rated" by some manufacture BS of x amount of watts ICAS Where they mean using SSB and not being a motormouth. Just make a comment or two and stop transmitting. Sure as hell won't stand up to any key down digital modes. But most rating of most things are highly overrated

Yep for sure. That is one reason I did the Harris for 6m and 2m. It was designed for 1100w continuous duty and will do 1500w without being into saturation. Running EME and Meteor scatter is hard on equipment. The 6m LPF failed at 800w FT8 after about 1.5 hours of an opening. I can say that I do trust w6pql for his ratings. He is a big EME guy so he builds stuff to last high duty cycles. But either way at those kind of power levels anything can happen.

Interesting paper on LDMOS ruggedness and some misconceptions about load impedance mismatches when it comes to LDMOS devices.  

https://cdn.thomasnet.com/ccp/30262309/222137.pdf

Very interesting. There are some videos by BBI where he runs an LDMOS box for around 4 hours with open and shorted coax and even welds with them. Obviously, he is not running the box at full tilt, but averaging around 400w output on a 2 device box.   There have been a lot of hams that have had devices burn up on them for a lot of different reasons. #1 is heat saturation is a big killer. Plus most of these designs are trying to squeeze all the power they can get out of a device. theoretically, you could run the supply voltage down, and double up on the devices in an amp, and run it without a tuner. Not that I would do that but reinforces my thoughts if putting a 2 pallet amp together that is capable of 2500w out and never running over legal limit.

One of the reasons the Harris is a good performer, 16 devices rated at 150w each. Limps along at 1kw

We are nearing peak ham radio. (Actually testing out business band antennas.)

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Oh my....that it the bomb.

Trying out the new mast for the 2m simplex net. Working well with the Slim Jim.

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That spiderbeam mast looks like it is pretty heavy duty.

I would not want to go any bigger and still want to carry it places in a backpack. If a person was shopping for one that would always be used at home or next to a vehicle……. A more sturdy one near the top would help with dipoles where you are supporting a balun up top capable of a full 100W.

I might try to run my 40m dipole wires from a cobra head connector next tuesday, as it weighs nothing compared to my 1:1 balun.