Fm / Am Modulation Meter Tf2300b Marconi Instruments

US $660

Springville, Tennessee, United States
Jun 5th

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The Marconi FM / AM Modulation Meter TF 2300B is an excellent modulation meter. It measures amplitude modulation (AM) for carrier frequencies between 4 MHz and 400 MHz and frequency modulation (FM) for carrier frequencies between 4 MHz and 1.2 GHz. Outputs are available for IF and 600 Ohm demodulated output. External oscillators can be used in place of the internal one. I bought this unit not long ago for a project and have upgraded. It is now surplus and time to go to a new home. Note the overall quality construction and that the extender card is still inside. Interior is clean. The exterior has normal ware and scratches. The exterior pictures I took make it look better than it does to me. There are what I would call homemade rack mount ears not installed but included. The wafer switches were given several shots of Deoxit. There is one case screw missing on the left side. I took good quality pictures. Look at the quality of the wafer switches! Will be HAPPY to send more pictures on request! Printed copy of op manual, PDF of what I think is the complete OP & SM on a CD, pictures used in this listing are also on the CD. home made rack ears and cord are included. AC line 110 / 220 VAC 45 to 500 Hz. 2 position switch on back. Ratings From the IB FM Accuracy +-3% FSD for deviations up to 500KHz and modulation frequencies between 30Hz and 150kHz +- 5% FSD on 1.5kHz range +- 10% FSD for deviations up to 500 kHz and for modulating frequencies 150 kHz to 200 kHz AM Accuracy +- 3% FSD for modulating frequencies between 30 Hz and 50 kHz up to 80% +- 5% FSD for modulation frequencies between 30 Hz and 50 kHz up to 95% TESTING Limited testing was conducted on the TF2300B using a HP 8648 Signal Generator. Result OK implies as close as I could read the analog Marconi meter. The frequency appeared where it is supposed to on the Marconi band dial. Setup call for setting frequency to the higher of 2 peaks. They are VARY close and not much difference in height. I couldn't tell much difference on this unit. On the AM 30% scale peak (P) & trough (T) 5%. 10%, 20%, 25% & 30% read OK. On the 100% AM scale 20% is about a needle width high P/T, 30% reads about 31% P/T, 40% about 42% P/T, 50% about 52% P/T, 60% reads 62% P/T, 70% about 72P 70T, 80% about 81P 79T, 90% about 90P 88T, 95% about 96P 95T, 100% Over scale P and 99% T AM setup pg 15 P(6) says it doesn't matter if modulation is on or off when setting "set AM" unless appreciable even harmonic distortion is present. Readings are within spec. either way however, they are closer if set AM is done with modulation on and rechecked when % modulation on input signal is changed. FM deviation 5KHz scale +/- 5 KHz is OK. 15K scale checked at +/- 5,10 & 15Khz OK. 50KHz scale +/- at 10, 20,30, 40 & 50KHz OK repeatable about 2Khz. 150KHz scale +/- 50, 100KHz OK. HP stops at 100KHz so was not tested higher. Book says recheck "Set Cal FM". It needed to be touched up or at least checked regularly. Compare my test results to the stated specs. For the record the HP signal generator was set RF frequency was constants at 100 MHz, Modulation frequency was constant at 1 kHz The operation / setup for measurement using the TF-2300B is not intuitive for me. I have to follow the OP manual procedure to get accurate readings. This Marconi TF2300B appears to be working properly, but it has not fully been tested. Therefore, it is sold as is. If it is not in a picture it is not included. Ask if you think I missed something in a picture BEFORE you bid. AND NO the HP signal generator is not included!!! Pickup is free as always. If you are a ham in a foreign country I will consider shipping to you after checking your call on QRZ. I expect the shipping cost to be prohibitive I have listed 3 shipping options. Note: Parcel Select may cost more than Priority. If you can figure a cheaper way to ship with with tracking I will use it. If you have a commercial UPS account I can use it to ship to only you at your address of UPS record and save you$$ I lean towards UPS for large heavy shipments