Show tho electrical schematic diagram of horold RP three tub bet using crystal detector by LEWIS WINNER in radio world A very simple three tube set using a costal as a detector la shown in the illustration the receiver employs one step of tuned RF with regeneration a crystal detector and two steps of transformer coupled quency amplification on most receivers no matter how many stages of tuned RF you add the signals of the local stations do not in crease much this was found to be true on man tests with such receivers the RF steps were so arranged that they could be snapped in and out of the circuit A station was tuned in the RF tubes were put in and then out of the circuit the difference was so small that only with in the output circuit could the effect be noticed there are only about a dozen leads to make no soldering Is necessary the orbit horold coils were used in the set also air gap sockets list of parts two tuned radio frequency trans formers tor olds 1112 1415 one 13 one crystal detector CD two audio frequency transformers afta afta acme one 1 ampere ballast resistors rl oliree sockets air gap two mad vernier variable con den sers with dials U S tool one single circuit jack or two phone tips jl one 3 inch dial for one A battery switch one 7 by 21 inch panel one cable cord one baseboard 6 by 19 by accessories bus bar mounting for crystal detector batteries phones an tenna ground and lead in wire etc the shaft of the variable condenser cl that shunts the secondary of the antenna coupler 12 passes through a hole 3 ag inch in diameter which Is 51 inches from the left hand edge of the panel and 3 inches from the top and the bottom lay the template over this hole and then drill the hold ing holes according to those laid out upon the template the same policy Is followed with the other variable condenser the hole through which the shaft of the 13 passes Is 10 inches from both the right and the left hand edges it Is also 3 inches from the top and the bottom of the panel the hole for the shaft of the last variable condenser Is 5 inches from the right hand edge and 3 inches from the top and the bottom of the panel the hole for the filament control switch S Is 10 inches from the right and the lefthand edges of the panel it Is s inch from the bottom of the panel this necessitates cutting away a small bit of the baseboard the holes for the screws which hold the baseboard are best located bv the builder as these depend upon the thickness of the baseboard etc I 1 used a comparatively thin board aad therefore had to place ahe screws very near the bottom of lie panel e hae now automatically placed the variable condensers baird and switch angle irons are used to mount the colls onto the condensers these condensers have special provisions for mounting the colls which are placed at right angles to each other the set of plates of one variable condenser runs in the opposite direction to the other set of plates that Is one condenser Is mounted upside down this was done 80 that the colls could conveniently be mounted if the condensers are mounted in the regular fashion it will be difficult to mount the colls the transformers are mounted at right angles to each other the crystal detector which Is of the fixed type has a special type of mounting you cannot fit it into a grid leak holder as it Is too small therefore take a calr of mountings and bolt them together seeing when doing so that the crystal fits into the holders you then have a perfect holder this Is then screwed down to the baseboard sand the crystal la fitted into the clips there was no jack used when this set was constructed although on Is hown in the diagram A pair of phone claps mounted at the extreme right of ithe act were used no large binding host strip Is used A battery cable waa used anstead and attached points to the proper wiring the set the beginning of the primary wind LI goes to the antenna post on the small terminal strip the end of the same winding ll 11 goes to the and binding post the end of the second an 12 winding goes to the G euclet 1 post on and to the pentes condenser CL the be of this same winding to the rotary plates of this varla bli condenser cl and to one terminal ol 01 the resistance rl now with the vari ometer you may have some difficult wiring up most have pots but some such as the one thai was employed la this set have noni at all if the latter case prevails scrutinize the very care fully see where the beginning 0 stationary winding goes fo and al where the end of the rotary winding goes to in most cases the stator wind ing terminal goes to one frame aej the rotary end to the other tram neither of these frames of course I 1 electrically connected after findan these connections place small tags oj them the rotary winding will tei malnate at the front of the varlo mete while the stationary winding will ter malnate at the back the rotary aln ing terminal goes to the P post 0 socket 1 the stationary winding goe to the beginning of the primary 13 the second the end goes to th B 45 1 of the cable the bagli nang of the secondary winding L goes to the variable plate of the var able condenser ca and to the B pos on the audio frequency tran stonne am the end of this winding goe to the stationary plates of the sam variable condenser and also to one tei manal of the crystal detector high p marked A on the the other crystal goes to the P pos of the audio frequency afta the F post on socket 3 goes to the other terminal of the r sl stance ill the G post on AFT goes to the G post on socket 2 th F post on the transformer goes t the same terminal that the of 12 went to or to one terminal 0 the resistance rl alie F post 0 this socket goes to the F post 0 socket 1 and also 3 this commo lead goes to one them sl stance this means that the resist ance Is in the negative lead of the fila ment the P post on the socket 2 goe to the P post on afta the B post on this socket goes to the bj B j 07 volt cable lead 2 the G pos on afta goes to the G post on 3 the plate post on the same goes to either the top terminal of th single circuit jack or to one tormina of the phone tips the F of socket goes to one terminal of the flit mant control switch S the other tei manal of this switch goes to the AB cable lead all the F leads aroi the sockets are common all the gri returns are placed in the negative lea of the A battery no 0 battery 1 employed although the same may b used if you desire to use a 0 bai tery break the two leads that corn from the F post of the two AFT an bring the same to the 0 lead of th 0 battery the 0 lead goes to th A lead gumplo to operate this receiver Is very simple to 01 erate the only trouble that you ma come up against Is the difficult coi trolling of the oscillatory flow of th RF tube tills Is due to the fact aba many vario meters will not over the complete broadcast band small 20 turn coll placed in series wit the plate circuit of this same tube wl cure this the two condenser dial should tune in step don t forget t reverse the leads of the crystal dete tor in case the signals are not lou enough also reverse the A batter leads A foot antenna should b used the ground should be made t the old faithful water pipe it yo find that the RF tube Is difficult t control the insertion of a 10 ohm rhe icat may help I 1 cay may because wit come tubes it helps and with other it Is of no use that Is you bring tb filament temperature up to a bertal point and the tube starts to oscillate oscil lat in the same manner if you turn 1 dow n it stops all together turn it ui it howls too much the li this set do all the controlling i the regeneration by increasing am decreasing the voltage better or results will be obtained try the tubes around for louder signals this receiver Is selective and if on finds the results vice versa they reverse the of the radio frequency transformers simple tube repair A tube with a loose base can be r paired by wrapping a strip of adhe alve tape around the joint three 01 four throes carefully stretching thi tape at each turn so as to fit over the top of the metal base and tl folasa after wrapping hold the rulx in alie closed hand pressing tightly 01 the tape for a few moments to hea the tape and make the support this will save the tub IM future asa |