I would suspect one of the relays in the path from the antenna, through the RX ant switching circuitry. Then there are the diodes in the t/r switch. If you have verified that the RX is working, it must have something to do with the path from the antenna. Does it transmit OK? The lowpass filters are in the main RX path, I think.
Vic 4X6GP > On 1 May 2016, at 12:57 AM, Udo Langenohl - DK5YA <dk...@dk5ya.de> wrote: > > Gents, > > I had another test session today with my K3 and here's what I've done and > what happened: > > 1. I've checked all the test points recommended by Elecraft. No issue found, > all stages are working, there's noise increasing on each test point at the > Main RX. > > 2. Fired up my signal generator again and started on the Main RX with a > signal on the following frequencies and with these results: > > Filter settings: 2.7KHz > Preamp off > Att: no > Signal strength: -63 dBm > Mode: USB > > 28.130 = S6 > 21.130 = S6 > 18.130 = S4 > 14.130 = S2 (!!) > 10.130 = S4 > 7.130 = S8 (!!) > 3.513 = S6 > > Same settings at the Sub RX (via AUX IN): > > 28.130 = S9+5 > 21.130 = S9+10 > 18.130 = S9+10 > 14.130 = S9+10 > 10.130 = S9+5 > 7.130 = S9+10 > 3.513 = S9+10 > > You will see that there are dramatic differences at the Main RX from band to > band and from S2 (14 MHz) up to S8 (7 MHz). And of course when comparing Main > RX with Sub RX. Also tried different filter settings (AM, CW), no change. > > I have no idea what is happening here and what to do next. > > 73 Udo, DK5YA > > >> Am 25.04.2016 um 22:02 schrieb Udo Langenohl - DK5YA: >> Gentleman, >> >> thanks for all so many replies. Will try to check all ideas tomorrow, >> XYL permitting ... ;-). >> >> 73 Udo, DK5YA >> >> P.S.: The issue occurs at the RX IN and TVTR IN ports of the KXV3A too. >> >>> Am 25.04.2016 um 17:57 schrieb Jerry: >>> Reseat the internal coax jumpers in the surf signal path. >>> >>> Sent from my iPad >>> >>>> On Apr 25, 2016, at 11:52 AM, Graham g3tct <g3...@g3tct.co.uk> wrote: >>>> >>>> Hi Udo >>>> Before you start tearing the rig apart, two ideas:- >>>> >>>> -is there a big difference for weak signals of say S4? >>>> -if not, it may just be the S meter calibration that needs attention. >>>> -if so, preamp on for either? Att on for main? >>>> >>>> HTH >>>> Graham >>>> >>>>> On 19:59, Udo Langenohl - DK5YA wrote: >>>>> Gentleman, >>>>> >>>>> I'm struggling with a Main RX vs. Sub RX issue. My Main RX is rather >>>>> deaf compared to the Sub RX. I see at least 23.5dB attenuation >>>>> between Main RX and Sub RX when comparing highly stable signals from >>>>> my signal generator (HP8664A). This is only for ANT1/2 vs. AUX-IN! >>>>> Example: >>>>> -33dBm on 28.500 >>>>> into AUX-IN (SUB RX): exactly 59 +40dB >>>>> into ANT 1 (Main RX): 59 +15dB >>>>> into ANT 2 (Main RX): 59 +15dB >>>>> >>>>> I've checked all the usual suspects (pin diodes): >>>>> D1 and D5 on the KXV3A: o.k. >>>>> Each and every pin diode on the SUB IN board: o.k. >>>>> D5 on the Main RX board: o.k. >>>>> >>>>> This is a K3 #59xx with almost everything inside money can buy. >>>>> >>>>> My second K3 (serial #39xx) does not show this strange behavior. >>>>> Main RX and SUB RX show exactly the same values on ANT1/2 and AUX >>>>> IN. -33dBm is 59+40 on MAIN and SUB RX, no matter if Ant1, 2 or AUX IN. >>>>> >>>>> Any idea? I'm searching for weeks now and I'm close to give up. >>>>> >>>>> Udo, DK5YA >>>> ______________________________________________________________ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:Elecraft@mailman.qth.net >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>>> Message delivered to je...@carolinaheli.com > > -- > ****************************************** > Webs by DK5YA: * > http://www.mmmonvhf.de/ [editor]* > http://www.vhfdx.de/ [owner] * > http://www.palekastro.de/ [owner] * > http://www.solweb.de/ [owner] * > http://www.spessartwetter.de/ [owner] * > ****************************************** > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to k2vco....@gmail.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
