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KC901V RF/AF Source Output Too Low -35dB on PORT1 and PORT2

By soasystem •  2018-04-29 09:58:18 •  386 clicks
i just noticed the RF Source output for my KC901V is too low at -20dBm to -40dBm on port 1 & 2 when checking with Advantest R3465 Spectrum Analyzer even though the RF AMP setting is at 0dBm. So i did AF & RF Source calibration in SysCAL menu (FUNC, Shift 7). After calibration, the RF AMP showing -20 to -40dBm, i cant increase the setting anymore to 0dBm, and the output is about that setting on Spectrum Analyzer. in AF Source and AF OUT port, i still can set to 3000mVpp maximum, Spectrum Analyzer reading confirmed this. but when changing to port 1 & 2 its -20dB to -40dBm maximum. The specification show RF Source should be able to output -6dBm to 13dBm. I think something broken in port 1 & 2 path. This happens on all frequencies 50 - 7000MHz.

How to deal with this problem? is this easily fixable? or should i ask for warranty repair? I bought this unit on Sept 2017, its only 8 months with very seldom usage and i only use RF Source couple of time and now its broken. If i ask for warranty repair, i'm in Malaysia and sending to China will involve high shipping cost. If Deepace can cover shipping cost, then its ok. but if i have to pay shipping cost, then its problematic. i only notice this because i just bought Advantest R3465 Spectrum Analyzer since KC901V Spectrum mode is not really usefull in full span sweep, so now i have instrument to cross check with KC901V. I'm not sure since when this broken, maybe even from factory?. I've provided proof picture (see attached) Any idea? Waiting your reply thanks.

ps: i will also send this to Deepace email, so i can get urgent reply hopefully.
11 Reply | until2018-09-22 09:19Add a reply
    VK3NH  108 days ago#1 -Reply

    @soasystem
    Shafri,

    That is great news that your KC901V is back repaired - well done.

    You can see signals above 0dBm by going into the level (amplitude) menu and setting the reference level to 20dBm.

    Th R3465 will handle up to 30dBm max but I would keep below 20dBm (100mW)
    The maximum level I have seen out of my unit is 14dBm.

    regards Noel


    charli  108 days ago#2 -Reply

    dear soasystem
    Result
    Thank you.
    Please use the bed without any fault.
    From Charli


    soasystem  108 days ago#3 -Reply

    thanks charli for your kind wish, i got my unit back today from Deepace after warranty repair (my own cost though on sending it out sigh). quickly checking my KC901V's RF Source on both port 1 and 2 with my R3465 SA, the problem is fixed now, the RF Source now outputting the correct 0dB on both port (with minor 1 or 2dB discrepancy which is acceptable to me, maybe also due to my R3465 is not very well calibrated) i didnt try higher level since my R3465 top reading only 0dB, i think i can make it read 10dB but i'm lazy arse and i'm busy with other stuffs, and i will be going abroad for the next 2 weeks. so i'm glad i got my unit back before that. Thanks to Deepace for doing the repair. i noticed when installing batteries, they also replaced the ribbon cable because it was in bad shape due to a number of time opening the unit, so double thumbs up to them.


    charli  128 days ago#4 -Reply

    dear soasystem
    I sincerely wish you a successful repair.
    Fire Radio Molora Engineer charli
    Expect good results.
    Please share your results.


    soasystem  129 days ago#5 -Reply

    and i've used this unit very seldomly within this past 8-9 months, not the 100% everyday use business. so i think something inside is really fragile to damage. i hope the repair will involve making the circuit more immune to damage and more robust, we dont want next time 2-3 months after warranty period, the unit will be damaged again. after warranty, this is difficult and costly for repair.


    soasystem  129 days ago#6 -Reply

    i already sent back my unit for repair under warranty yesterday. from our email, Deepace indicated this is hardware issue and provided me with address to send back my unit. Hope they will repair soon. I got charged $89 by DHL duh.

    For info. I've never connected my unit to any serious active device or any Vdc. I'm aware of the input safety to avoid overloading and damage. and i've tried many settings including system recalibration, but i still cant get back the 0dBm on RF Source output. The only active device connected is a China ADF4355 Signal Generator powered from 5V USB power supply, that i bought separately to learn mixer with KC901V and Advantest R3465. Now my KC901V is broken, i have to wait for repair before i can continue learning and designing RF circuit again.


    charli  132 days ago#7 -Reply

    Improper fine tuning can cause many tolerances.


    charli  132 days ago#8 -Reply

    dear soasystem
    Owned KC-901 V measuring instrument
    Is it not an input RF signal overload damage?
    Or do you want to reset it to the factory?
    Please share your results with the Forum. I'm curious.


    soasystem  140 days ago#9 -Reply

    i tried that. still same.


    charli  143 days ago#10 -Reply

    AF


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