The original shipping carton is satisfactory, providing the original inserts ore used or sufficient packing material is inserted to keep the instru- ment immovable. A separate bias supply, employing a selinlum rectifier SRI in a half- wave circuit, provides the necessary fixed bias for the output tubes. Anything else is just asking for trouble, either for you or for the modulator. In any case, never leave the mod- ulator in an operative state with the bottom plate removed, especially if children have access to it. This item may be a floor model or an item that has been returned to the seller after a period of use. You can put the on meters with minimum work. The use of feedback greatly reduces distortion and ex- tends the range of uniform frequency response, resulting in increased clarity and pleasantness of speech.

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Bias is obtained with an un-bypassed cathode resistor R6, which also provides negative feedback for reduced dis- tortion in this stage. The Model is moudlator for operation at a line volt- age of 1 17VAC. Remove electrical tape holding black-green lead to black-red lead. Sell one like this. To do this, it will be necessary to remove the bottom plate and connect the black-green lead V power transformer primary tap to the AC switch terminal Sl-1 instead of the black-red lead V primary 7300.

The key is to properly load the output with a resistor which will take the mod power. Transformers, capacitors, EM tube all good See original listing Eico modulator needs tubes.


The out- put of the clipper is fed throughalow pass filter LI, C5, and C6 to suppress high order harmonics generated by peak clipping. The Model should not be operated wi thout a proper load under signal conditions, as the high voltages gener- ated in the modulation transformer may damage it.

Eico modulator needs tubes. Transformers, capacitors, EM tube all good | eBay

Fixed bias is obtained from a sep- arate adjustable bias supplyand a balance potentiometer. You do not need to use any more than that for good conditions. An EM84elec- tron-ray tube V6 provides visual indication of over-mod- ulation when the Model is employed as a plate mod- ulator.

To afford conservative operation of the unit in areas of high line voltage, both IITV and V taps have been provided on the primary of the power trans- former. This item will be sent through the Global Shipping Programme and includes international tracking. You outgrew the DX60 once you upgraded.

The had a multimatch transformer for various impedances, and allowing its use with other transmitters. At the ON position, remote con- trol is disabled. The negative feedback loop makes the audio response very flat and clean. Input for high impedance crystal or dynamic microphone. An item that has been previously used.

The common deficiency noted with the DX60, Ranger, and others plagued the rotary mode switch in the Eico It used commonly available 6CA7 hi-fi tubes used in the great Dynakit Stereo 70 amplifier. Another important value of feedback is the considerably improved regulation of the output, which is useful when the mod- ulator is used to drive a class B load.


See full item description. The high-power modulator will usually have a plate meter which serves this purpose.

Eico 730 modulator/ driver

A negative voltage then appears at the grid of V6, causing the modylator green indicating bars of the tube to overlap. SERVICE If trouble develops in your instrumentwhich you can not remedy yourself, write to our service department listing all possible indications that might be helpful. Eico manufactured a lot of test gear, audio gear, and some ham gear. Moeulator tag to the instrument, giving your home address and the trouble with the unit.

An RF filter Rl, Cl is employed at the input of the first stage to eick any tendency to- wards RF feedback through the modulator. Upland, California, United States. In addition the effec- tive speech level of the signal will be raised db. The Eico modulator was a stellar performer.

Ail resistance values meoiured to chassis with pin 8 of the GZ34 tube grounded except, of course, when the resistance to rico ot pins 2 and 8 of the GZ34 is being checked. Pack very carefully in a rugged container, us- ing sufficient packing material cotton, shredded news- paper, or excelsiorto make the unit completely immov- able within the container.