Flex 5000 bad BC/SW images on 160M, also only 50 watts out problem.

Doug Allen

I think the low power and the image problem started at the same time. On 160M I have BC/SW images almost every 10 KHz (none with my Flex 1500).  I can attenuate them for 30 seconds to a minute or so by applying power, either TUNE or ATU, but they gradually get stronger again within a minute.  Some are over S9.  Maximum power out on all bands is 50 watts.

Ken Akin

It is likely that the database has been corrupted, have you tried restoring a clean copy or rebuilding?

My rig is on the other side of the house (separate PCs) so I will not mislead you with what I may not remember in detail.

73

Ken  AC0HO 

Doug Allen

Thank you ken.  Not sure I understand?  The Power SDR database? I have tried two versions of Power SDR, but not the latest version.   Or is there a software database for the Flex 5000 hardware I can download? 

Ken Akin

Doug -

Sorry I didn't see this earlier. I need to be in PSDR to give you a useful answer, and that will be tomorrow afternoon.  When you install PSDR and define things as you want (tune level and output levels are what I go for, and you can do this for each band). You can/should then save this image, and save a new image anytime you make a change, PSDR attaches the date and time so you can keep a number around.  NOTE - when PSDR is first installed, output is set to 50, that very likely is where your 50 watts out comes from.

Ray, K9DUR has a nice utility for managing these (the DB may be re-formatted between releases), see his web site for details, I think his utility is now included in the most recent PSDR.

Every time you start PSDR it picks up this little DB image that you last used. When things go funny it is likely that something overwrote part of the DB. If you have a stack of the most recent ones, you may elect to load a previously used DB. If you don't have any saved you get to start from scratch (not really that big a deal).

I'll try to follow up tomorrow if someone else hasn't already helped out.

73

Ken  AC0HO'

 

Stu Phillips - K6TU

Doug,

I am guessing especially since I don't know where in the US you are located, but I suspect the protection diodes on your 5000 have been compromised by a high static spike - perhaps from a nearby lightning strike.

The protection diodes although not conducting are acting as low level mixers and that is the cause of the spurious signals you are seeing on 160m.

A cure (and a good one) is to get a transmit capable HPF that has a cut off right above the broadcast band - ICE used to make one and I know there are others.

This will keep the RF energy from the BCB hitting the protection diodes on your 5000 and causing the mixing effect.

Here in the SF bay area where I live,  the hottest AM station is -8 dBm and there are many at -10 dBm...  lots of heavy RF energy here.

When I had my 5000, the BCB HPF filter was a necessity (as it was with several other rigs including a K3 of one of my friends) and nailed the issue once and for all.  A filter in the RX loop was not sufficient as the BCB RF still got to the protection diodes.  That said, the second filter in the RX loop helped further reduce the background noise level on 160m.

For reference, with my 6700, I have dispensed with all external filters and have no intermod/intermixing problems.

Stu K6TU

Ken - NM9P

I saw a posting a month or so ago where someone had lots of intermod problems caused by a defective cartridge in a lightning supressor.

Doug Allen

Thanks Stu,
  The high static spike and the faulty protection diodes are a possibility.  I just interfaced my Flex 1500 to the same computer and Power SDR 2.6.4, and there are no BC or SW images on 160 M using it.  

The strongest local BC stations here are much weaker than yours in San Francisco, - 37dBm on 910 and -28 dBm on 950.  They are also weaker after sunset.  Nothing much stronger than -40 dBm right now on SW with my 160M Inv L, and think the 160M feedthru/images are BC and not SW, but I haven't verified that.  What are my options for testing and fixing protection diode?
Doug K4LY

Doug Allen

Thanks Ken,
   I'm studying the manual.  I know how to set the band power out for transverters, but not for  straight through except on the Power SDR front panel power meter.

  I have been auto saving TX  Profile on Power SDR Close, but not Auto Save TX Profile on Change so I guess I don't have the earlier profiles when I had full power output.   Back to the manual.
Doug K4LY

Stu Phillips - K6TU

Don,

The test using your 1500 eliminates an external source like Ken suggested from a partially hit lightning suppressor.

I believe that all AM stations (except perhaps the ones that have a "clear channel" license) are required to drop power at sunset - I've seen circuits for AM band power scavenging for micro-power applications like the so called Internet of Things devices...

What you see on 160m, particularly if its spaced avery 10 KHz, is intermixing of different AM band stations by the protection diodes.  In my case, the diodes were fine but the level of RF energy from the BC band was enough to generate the intermod.

I eliminated the problem with an ICE 402X filter...

http://www.iceradioproducts.com/filtersrf.html

I would give FlexRadio support a call and discuss the issue with them.  I'm not certain how you can test this as I'm note sure where the protection diodes are located in the antenna switching matrix.

Stu K6TU