There is very limited information about the summer 1920 broadcasting activities of the Western Radio Electric Company's experimental station 6XD, Arno A. Kluge's experimental station 6XN, and Fred Christian's amateur station 6ADZ, although Christian, who was an Electric Lighting Supply Company employee, has been traditionally been said to have begun on September 10, 1920.

These three efforts eventually evolved into the first three formally licensed Los Angeles broadcasting stations: KQL for Arno A. Kluge (October 13, 1921-June 9, 1922), KGC for the Electric Lighting Supply Company (first licensed December 8, 1921, now KNX), and KZC (later KOG) for the Western Radio Electric Company (December 9, 1921-March 9, 1923).
 
Radio, November 1921, page 149:

DEVELOPMENT  OF  RADIO  TELEPHONE  AND  C.W.  IN  SOUTHERN  CALIFORNIA

    The usual crowd, gathered in Wesrad's store the other day, began swapping reminiscences, and it was amusing to reflect on the rapid development of the radiotelephone and C.W. during the past year. Such tremendous strides have been made that contemplating the future -- yea, even the near future, is a thing of only the wildest conjecture.
    A little more than a year ago, Western radio burst forth on the ether with the first vacuum tube telephone transmitter in this locality. The effect was startling, although the phonograph concerts were much worse than the worst concerts you hear nowadays. On one particularly good night, a conversation was carried on with 6NY, in Whittier, about 20 miles distant. This was stimulating and experiments were "carried on" with renewed vigor. The transmitter, at that time, employed four De Forest tubes, little better than amplifiers, and using the De Forest system of grid modulation. The four tubes were all used as oscillators and the radiation meter ambled up to one-half an amp on state occasions. Those were the happy days!
    Then Arno Kluge began juggling the intricate parts of a telephone transmitter and tests were carried on over the intervening blocks with beautiful regularity. Very shortly after Lex B. Benjamin, 6MK, and president of the Southern California Radio Association; and C. E. Blalack, 6JE, entered the C.W. field and from thenon new radiofones appeared at frequent intervals.
    At the present writing there are about 20 telephone transmitting stations operating in Los Angeles. Some of these stations are concert sets operated by the various dealers on scheduled evenings and the foremost transmitter is Wesrad's 50-watt set, which entertains all the surrounding countryside on Tuesday and Friday evenings.
    It is interesting to compare the present 6XD transmitter with the original described above. The circuit has recently been changed and improvements are made almost every week. A great deal of experimentation is necessary to bring this size of transmitter to the point of perfection which it is desired to obtain. The present circuit is a great improvement over previous circuits used and in a coming issue the complete diagrams and data will be shown in these columns.
    The Western Radio Electric Company has been foremost in their activities in introducing radiofone and C.W., as it has been their policy to remain abreast of radio advancement for the benefit of the trade. The Oakland store of this company will carry the same policy of sales and service into the San Francisco bay district.
Radio, March 1922, page 33:
Obituary
    Died, in Los Angeles, on New Year's Eve, 1921, Arno A. Kluge, at the age of 23 years. It is with deep regret that we chronicle the passing of so promising a young man at such an early age. Born at Ravenna, Neb., where he had his early schooling, finishing high school in 1916, when he removed to Lincoln in the same state for the purpose of attending the university. He had two years of that work, during which he also served as instructor in the Signal Corps of the U. S. for drafted men from Nov., 1917, to July, 1918. In Jan. of the latter year he had his first break-down, and came on to Los Angeles in Sept., disabled by paralysis. In March, 1919, after a stay of five weeks in the hospital, he came home in a helpless condition and was always thereafter confined to his chair when about the house.
    Wanting to do something for himself, he engaged in the sale of radio apparatus, often assembling sets for his customers, and built up quite a trade. He also did typewriting and wrote articles for the magazines. He had a wireless telephone, and his concerts, under the call 6XN, which had become a regular thing, will be missed greatly by his many friends. 		Arno A. Kluge
Los Angeles Evening Express, September 3, 1925, The Radio Weekly Supplement, page 21:
 
Pioneer  Radio  Days  Here
         Recalled  by  Local  Dealer
Fred Christian
    In the early part of 1920 there came to Los Angeles a very ardent radio enthusiast. He had been a ship's radio operator on the Atlantic coast for some time and had engaged in a small, limited radio business in Norfolk, Va., previous to his arrival in California. His intentions on coming to the Pacific coast were to ship out and have a look at the Orient. Instead of this, he connected with a prominent Los Angeles electrical house which had been doing business for many years in the electrical appliance line. This house was the Electric Lighting Supply Company owned by C. F. Baker and located at 216 West Third street. The new arrival was Fred Christian.
    The radio department of the Electric Lighting Supply Company began in a very small way. There were not very many people interested in radio and a few hundred dollars a month was considered good for this department. At that time there was but one other radio store, the Western Radio Company, owned by Les Taufenbach, and a small manufacturing plant in the city of Los Angeles. Now, in September 1925, there are 230.

SHIPPERS MAIN PATRONS
    The class of trade catered to in those days consisted of a few ship operators who drifted into town and needed vacuum tubes or batteries and parts to operate these tubes. There were also a few amateur transmitting men who occasionally needed apparatus and who came to look to the Electric Lighting Supply Company as a source both for information and apparatus. These men formerly purchased their apparatus through mail-order houses in the East.
    The Electric Lighting Supply Company had established an amateur station at Christian's home, using the call letters 6ADZ. Through this station this company kept in touch with its potential customers, the amateurs.
    With the advent of the Avalon radiophone a great increase in business was felt. People purchased sets for the sole reason of listening to the interesting conversations between husband and wife, youth and sweetheart, or the Avalon grocer and his wholesale store! Radio was going ahead very rapidly even in these days.
    Christian, together with the late Arno Kluge, established the first two broadcast stations of Los Angeles. These stations were the first to be licensed under regular broadcast call letters. They were KQL and KGC. Five watt haywire transmitters, designed by Kluge and Christian, were used. Phonograph records were the sole source of entertainment.
    These broadcasting stations served to greatly increase radio business and many other stores took up the sale of radio apparatus. Other broadcasting stations, mostly of 5 and 10 watt power, sprang up over night, and in 1922 there were 19 stations in Los Angeles and vicinity, all wanting to broadcast at the same time and having to use one wave length, 360 meters. KGC was transferred from Christian's home to the California Theater and began the first radio KNX. Varli Elinor's 50-piece orchestra was broadcast nightly.

BOOM DAYS OF RADIO
    These were the boom days of radio. Everyone from cigar and drug stores to music houses installed radio departments. The country had gone completely radio mad. Manufacturers, not expecting this boom, were caught unprepared and were unable to meet the demand. They finally got going full force and accumulated big reserve stocks. Then the unexpected happened. During the latter part of June the slump came. Dealers were caught with their shelves full and manufacturers with their warehouses full. As many as 60-odd dealers in Los Angeles "went broke" in less than one week's time!
    Much of the material manufactured for the boom was junk and made by people who had no idea of radio or its theories. This merchandise was thrust upon the people by many unscrupulous dealers even as late as the fall of 1923.
    The Electric Lighting Supply Company was one of the few firms which had not stocked this junk apparatus. Christian, who had been in the radio field for some time and who had had enough merchandising experience to cause him to buy cautiously, kept his shelves clean of unstaple merchandise.