weatherman i have made a few small dummyloads over the years,
the last 2 i built i used 100 x.6w 1% none inductive metal film resistors and 100 x 2w because they were cheap and i needed a load larger than the average cbshop dummyloads,
they can work ok at cb frequencies providing the resistors are none inductive types and you keep the leads as short as possible when you assemble it,
i gave my ham buddy the 200w version and he claims it works fine for him at hf frequencies,
the 100 x .6 would be rated at 60w but i have used it at 300w for short bursts long enough to take a reading,
the resistors i used are rated at 10x their continuous rating for 10 seconds so a 4 second burst wont hurt them or get them hot enough to change resistance enough to matter,
to construct it i soldered 3 pieces of pcb into a u shaped channel with a c0pper wire running down the middle to the so239 which was in turn mounted onto the lid of a large treacle tin,
next i soldered 3 rows of resistors between the wire and bottom and sides of the u channel keeping leads as short as possible about 1/16",
after checking with a multimeter i had to add a few more resistors to get exactly 50ohms then tested the vswr to see if the setup was reactive at cb frequencies,
luck or not they both worked ok for general testing of cb's and amps with a very low vwsr and much better than my earlier efforts,
if you do happen to get it too hot and the resistance goes up you can add easily extra resistors to get it back to 50ohms,
i tried filling the tin with different oils but they all screwed the vswr up so i cleaned them off and drilled holes in the top and around the bottom to allow some airflow,
its not the best way by any means but if youre bored and need a cheap load that will do a reasonable job on lower frequencies then this would give you something to do for a hour or two,
good luck with whatever way you decide to do it
