The earliest radio amateurs were often in their teens, and they also had to build most of their transmitting and receiving equipment themselves. The reference to "bits of arc-light carbons, with ordinary sewing needles laid across them" is a description of a "loose-contact" receiver, while the "acid receiver" refers to a recently introduced, and more sensitive, receiver which had been developed by Reginald Fessenden. But both would soon be supplanted by introduction of crystal detectors, which were more sensitive and reliable.
Technical World Magazine, September, 1906, pages 62-63:

Wireless  Station  in  Henhouse
By  M.  W.  Hall
Lloyd Manual WHILE, to the layman, deep mystery surrounds wireless telegraphy a dozen Newport, R. I., lads are running practical plants of their own manufacture. Some of the boys are high school students, but the more ingenious electricians do not boast such extensive learning. The two showing the best working plants, in fact, are but sixteen years of age and belong to families that can ill afford to spend money for whims. Hence equipment that had to be purchased at market prices is a rarity with them.
    Still, with this difficulty facing them, their plants have been developed and proved to be of such practical value that the attention of the Navy Department has been attracted to them, because of their ability to cause serious interference with the powerful plant at the U. S. Torpedo Station, which has cost thousands of dollars to install and is costing hundreds of dollars each month to operate.
    The boys are not inventors, perhaps, but they show inventive genius in manipulating such defective equipment as they are able to secure, either by manufacture or purchase.
    Their crude plants have been inspected and reported upon by Commander Albert C. Gleaves, U. S, N., of the Torpedo station. His report to Washington speaks of the boys as most ingenious in their work. They have proved conclusively that fairly effective wireless outfits may be made to sell for not more than $50, with good profit to manufacturers; that small, as well as larger vessels may have wireless outfits, if they can afford operators; that, on shore, the army and civilians may make use of the wireless means of communication, where the cost of the construction of pole lines has been considered too great for the service desired. Charles Fielding, Jr.
    Aside from the fact that the boys have set up plants which send, as well as receive, the ingenuity which they have shown is, perhaps, the most interesting part of their work.
    For tuning coils, glass jars, mailing tubes or even curtain rollers, wound with wire, with a sliding contact, have been made to serve.
    For receivers, bits of arc-light carbons, with ordinary sewing needles laid across them, have rendered effective service, though a more sensitive one and one less troublesome when constructed is the acid receiver, which they have now introduced.
    They take an incandescent electric lamp socket, fix it to a table and connect with the outer pole, then take a lamp, preferably of the long finger type, cut off the upper end and remove the carbon, but leave the platinum wires. Then they pour in nitric acid, adjust another platinum wire from the top, and seal up the tube. This done, they have only to make their connections, listen at their telephone receiver and catch the wireless talk, provided that the wave detector is properly adjusted and the rest of the apparatus in proper order.
    While most of the boys are obliged to hold the instrument to their ears while receiving, one of them has arrived at the stage where his receiver is audible in all parts of the room.
    An old telegraph key connected with a spark coil, sometimes with a spark thrown between two nails driven into a board, serves as a sending apparatus in lieu of something more elaborate. apparatus
    This far the boys have not been able to send more than two or three miles, but they have received messages sent at a distance of forty miles. They are increasing their sending powers and hope, at no distant day, to have plants as powerful as those operated on the Fall River steamers.
    The two boys who lead the others in the eyes of the professional operators are Charles Fielding, Jr., a Postal Telegraph messenger boy, and Lloyd Manuel, who spends most of his time in his station, which was, until recently, a hen house. It is to these two that the other boys go, when in need of technical advice. They read all the wireless literature that they can lay their hands on and are well versed in the history and construction of the several systems.
    For some time the families of the young experimenters looked askance at the work they were doing. But when the attention of the government experts was attracted, their elder relatives decided that possibly, after all, the boys were not entirely wasting their time. Both young Fielding and Manuel are devoting their best energies to the attempt to discover improvements on the present apparatus. Neither of them has any desire to work as a wireless operator for more than a few months. Their ambition is more soaring than that. By making some invention of importance to the art, each of them expects, to reach not only fame, but wealth. Their future careers will be watched with great interest by many people who like to see boys display energy, enthusiasm and ingenuity.