It took about 5 hours of work to get it to this point. I was being extra careful with it, taking my time, etc. I won't get to test it for a while. I still need to make some cables for it, but for now I am burned out. It will have to wait for another time.

I do have a heat sink, enclosure, LPF, and the parts needed to build an interface for the band switching function of the LPF. I still need to order a little 12V cooling fan. I will need to drill the heat sink for relief cuts to make room for the SMA connectors on the bottom of the board, and drill and tap it for the transistors and the mounting holes. I suppose I should find a way to install a fuse too. 

I had some teflon tubing left over from a different project so I used it to help insulate the little choke on the power input. I read somewhere online that the insulation on the wire they supply is pretty weak, and it was. 

I'll need to make some SMA terminated cables to connect the LPF and the SO239s on the enclosure too. I could have just hard soldered it in but I figured I might as well make use of the connectors. And it will allow for future changes if needed.

That looks great!

You are much further ahead than I'm. I have not found motivation to work on it yet. The version I bought has no RX/TX switching relay. I'm thinking of using 2 Omron relays, similar to yours, with 1000V contact isolation. One relay will switch the RX/TX and the other will be connected through a diode (coil circuit) and will switch bias. The diode should provide short delay for the bias circuit.
BTW, cool board "holder". I did not know those things even existed. I just put a thick cotton fabric sheet on the desk and go for it. It also helps to spray the chair and the floor around the table with anti-static spray, although static is not an issue during summer time here. I do wear a grounded "bracelet" anyway. It's a single use bracelet that used to come with "Allen Bradley" PLC IO boards. People usually throw them away but I saved them.

Are you ready to try it yet? They should have at least included a spare set of the finals and maybe a driver too. You never know.

The only spares they included were SMD resistors, caps and a spare voltage regulator and a spare bias pot. I didn't use any anti-static protections, but I have been running an evaporative cooler so the air is pretty moist indoors. Hopefully it's all functioning ok. 

I won't be ready to test for a while. I just managed to get some time because the wife went on vacation with our oldest daughter so I had some time I could actually concentrate no something for a change.  I figure i'll just use a cheap CB into a dummy load rather than test using my FT817 until I can be sure it is ok. I did find a blog post from someone who built one that mentions the input SWR goes up as power goes up. So that will be something to keep an eye on. 

The board holder I got from Amazon for like $12 IIRC. It's handy. I got tired of using the alligator clip "helping hands" to hols small boards and this is much easier. You can tilt the board along the long axis too. One end is spring loaded and you can easily clamp and unclamp it to take it out for spot cleaning flux, etc. It adjusts to a pretty big size. I think it would hold a 10" wide board, maybe even bigger. 

Cotton? Anti-static spray?

You can't feel or see the kind of ESD that destroys semiconductors. May I recommend some cheap insurance, OM?

https://www.amazon.com/dp/B00O0Q03KM?tag=vglnk-c102-20



One of these is not a bad idea, either:

https://www.amazon.com/dp/B004K1F2NA?tag=vglnk-c102-20

An ESD safe chair and floor mat is also a good idea, but now we're talking real money. My lab floor at home is concrete so I'm OK there, but I sure do wish my surplus lab stool was ESD safe.

Be sure to ground your soldering iron, too.

ESD war story: joined a new company some years ago. The training division (not mine) did some basic electronics training. I got roped into teaching a few courses because their instructor left suddenly. The training involved soldering together various circuits, some of which that used 555's, PIC's, etc. The staff was used to helping students replace dead chips and just chalked it up to the cost of business, but it wasted tremendous amounts of lab time debugging student's otherwise perfect work. It was no wonder, the training room, while uber modern, trendy and comfortable, was an ESD disaster area. Carpet, vinyl chairs, lots of nylon and cotton clothing, non-ESD benches, etc. I had them provision mats and straps and ground the soldering irons. Next class we didn't lose a single chip. Class went super smooth. All of a sudden the company was glad the old "instructor" had left

P.S. Board holders are cheaper than dirt, btw:

https://www.amazon.com/dp/B00Q2TTQEE?tag=vglnk-c102-20

I'm old school. When I learned about working on electronics, none of the fancy things were available. I learned the simple and inexpensive way. I'm not going to spend money on something I use once every 3 months or less.
Of course I know about anti-static mats and have several at work. I never ruined anything doing it my way and I have worked on many expensive radios and amplifiers. As a matter of fact, i just repaired a friend's ALS-600 amp that required new finals and some caps replaced. The cotton pad is for protecting the desk and it does not melt if heated, like synthetic fibers. Anti-static spray is a cheap insurance although it's not needed at this time of the year. Soldering iron is grounded (Hakko) and i wear a special anti-static wrist band, also grounded through a resistor.

BTW, when I lived in Arizona, ESD was a major issue because of the dry climate. Right after I moved there, the phone rang in my apartment and I ran to pick it up. Right before I touched the phone, I felt a huge jolt in my hand and i fell on the floor. The discharge ark was several inches long. I will never forget this.

BTW, when I worked at a manufacturing plant. I would not allow any of my maintenance guys, especially electricians, to wear any synthetic shirts or pants. All of their clothing had to be 100% cotton. It was a part of the new Arc Flash requirement. It has nothing to do with ESD protection but some of them bitched about it. They also had to put on "monkey suits" when they worked on some electrical panels and motor control centers. The suits were made of 100% cotton too. It was done to protect them from an electrical arc flash. I had to wear all cotton too to set up an example. Ever since then I always try to wear cotton when working on electrical panels.

That's cool. You really need a signal generator and a scope to check the circuit before connecting it to the radio.
BTW, I don't see any variable resistors in there, unless I missed it. How will you adjust and balance idle currents on the finals? It's one of the first things to do when you power it up (in my opinion of course).

BTW, I've been thinking about picking up some testing equipment for my bench.  Obviously I will not spend a lot of money for the high quality stuff but some cheap Chinese units get pretty decent reviews. One thing I would not go cheap on is multimeters. I only use Fluke meters. Another thing is scopes. Digital ones are ok but I also need to find an older analog scope too for testing audio circuits and similar things where instant response is required.
Any suggestions?

I don't know how all those old radio shack spring terminal electronics kits survived without ESD protection, but they seemed to do ok.

There is a tiny little SMD pot on the board, on the input/output end of the board near the smaller transformer. 

You can see the schematic here:

http://pa-11019.blogspot.com/2016/11/diy-kits-70w-ssb-linear-hf-power.html?m=1

Ok. I see it. Good. They probably included a single turn variable resistor. Those can be tricky to adjust. What value is it? I may have a small multi-turn potentiometer in my components drawer.

ESD protection is a lot about common sense. Some components are very sensitive, especially some older microchips. Newer electronics, not so much but common sense should be used when working on them. Some old processors were very sensitive for temperature. 30 years ago, I had a homemade (circuit board and everything) computer based on a Z80 Zilog processor. That sucker would quit working if temperature dropped below about 35 degrees F. LOL

I don't know the value of the little pot. It isn't called out on the schematic and it's so tiny I couldn't read it if I wanted to. 

At the link I posted, the author mentions adjusting the bias higher than the 2.7V specified on the schematic to reduce SSB distortion at lower input power levels.