Well that depends on what you really want and how much reliable rms power you feel you need to have.
I would recommend you get an amp from Telstar Electronics. I am not not only the president but I am a client too! LOL I am just a customer. Seriously though I own some of their products including an amp and I love their products.
Keep in mind his has SWR protection, reverse polarity protection, thermal protection and true AB bias that is compensated constantly with temp. so it stays in class AB constantly. Check out the PDF for each amp. Also keep in mind his power rating are done at 14.2 volts not somethign crazy like 18-21 volts. He is not dead keying 40 watt's swinging to 120 to drive these.
I do not generally consider so called "custom" builders because they can not or will not give me true AB biasing, thermal and SWR protection. I also would not buy from anyone using fake or generic no name transistors that do not have published white paper's and OEM accountability. These unit cost too much and you often have too long of a wait time to mess around with no-name Chinese clone parts.
I am not going to lie I wish he had a 4 transistor amp instead of just 1 and 2 transistor amps but it is what it is. I am not aware of anyone else though with the mix of features and low harmonics at 5th and 3rd order. These things are clean and efficient and they are using all name brand components. They are not for everybody. These are more like what you would expect to see in amateur community and not what you would expect to see in the CB world especially the single transistor tuned input model!
I want to add that a lot of custom builders have had to stop doing repairs because they can not keep up with production demands due to all the repairs. I have never seen so many bipolar mobile and base amplifier's failing left right and center in my life! Instead of units lasting a year or more between failures a lot of these units seem to be failing with in months. A lot of them are making a circuit interns of being sent to different shops each time for repairs because they can not make them hold up and they are trying to find someone that can fix them "right". I think the archaic designs combined with low quality parts and unrealistic power outputs has created a "perfect storm"!!
If you can operate them as intended and are not chasing watt's and over driving them I think you would like Telstars amps. If you can not operate that way you are prob. better off with something from your typical CB amp builder.
I was going to try BBi or Tech-Nine and I was going to order an amp that had 2X-3x more rms output than I intended to ever use in (AB) bias and with SSB delay. I was going to get Toshiba, MACOM or Motorola transistors. I was planing to get a 4 transistor amp then under drive it with my old school President Lincoln or a modern RCI 2950DX.
In the past I used a 2xMRF455 amp and had it set to swing to about 65 watts on AM and PEP 100 on SSB and I talked all over the world with that DX'ing and easily talked in the 30-80 mile range on AM to other mobiles and base stations daily. For 8 years I talked on it that way and never had a single part fail in the amp. I had a crystal filter and power regulator fail in the RCI2950 I used with it. I could have gotten that output from a single MRF455 especially back when I built it since you could get inanely high beta transistors back then from Motorola. Occasionally I would turn the unit up but not very often.I had assembled that amp from a kit and had modified it as I learned more and more. One of thing I did early one was pressurize the cabinet like you do on a tube amp. I also regulated the fan so it was not dropping off with load. I had temp. control initially to turn it on and off but went to continuous instead. I had a filter on the air intake that kept the fan blades and the inside of the amp nice and clean. When I started to repair and build tube amps I did the same thing. I run them ridiculously under driven and keep them very cool! The same extends to the radio. Well I have never pressurized a radio cabinet or filtered it but you get the idea. I am a electronic hack at best. I can follow a schematic and mild troubleshooting but I do not understand it well like some guys on this site. Often I have to be reminded of the obvious and ask for help. Even when I know the answer I often am asking the wrong question!
99% of people order too little amp and then they drive it near it's limit 90% of the time with cheap poorly terminated coax. They fail to take into account that most amps are rated at PEP and are over rated or optimistically rated at that. They then dump a dirty signal from a radio poorly aligned or worse modified poorly. This creates a lot of heat in the amp and power reading that do little to nothing for you. They stuff them some place with little to no airflow. Not exactly a recipe for long life and clean signal. On Cb mobile or base they almost never use a balun or ugly choke depending on the situation. Even something as simple a ferrite beads are almost never used.
With smart ordering and attention to details you can easily get an amp even a poorly designed archaic one to last a long long time with clean output and lots of durability.
If you go the custom builder route you can have them put a 4 transistor amp on a heat sink and in a case designed for an 8-12 transistor amp. this gives room for future upgrades and it gives you more space for air flow and it gives you a lot more heat sink than you will need if you never upgrade. In a mobile amp you can never have too much heat sink!!!
Due to my aviation and military background I love durability and long service life. I would rather have too much durability and stability in my electronics if weight is not an issue than not enough. Since I do not carry my radio or amplifier on my back my car does I love lots of heat sink!
I hope I have not insulted you and I know I over simplified things but it pays to think far ahead and to have more amp than you need or plan to need with lots of headroom for future growth. The above is my opinion and other's will have vastly different take on this based on their experience.
