Birdie repeating every 100kHz

[JJ4SDR]

I am not sure if this is hardware or software related (perhaps this has nothing to do with the ANAN 7000 DLE MKII at all), but on 17,15,10 and 6 meter bands I see a "birdie" that repeats every 100 kHz. Any suggestions on where to look? Running Thetis 2.8.11 (10/20/20).

Best!
Juha
NI2M

[w9mdb]

Can you post a snapshot?

[JJ4SDR]

See 3 images (6/10/12 meters) to give some idea. Yes, the 12 meter images shows birdies out of band, but they repeat every 100kHz.

Juha

[w-u-2-o]

Not a Thetis issue (moving the topic).

Have you tried a different power supply? Run the ANAN off of a battery? Run around the house turning off circuit breakers?

[w9mdb]

I'm seeing similar birdies on my 7000DLE MKII.
Have to hook my ANAN100 again and see if it sees them.

It's a CW signal with a quickly varying amplitude. Wonder if it's some internal oscillator?

Mike

[PD3LK]

Try disable 6m LNA RX and TX : Setup, General, Ant Filters, tab BPF1/LPF
(for SDR-Console users: do the same)
73 PD3LK

[w9mdb]

6m LNA enabled or disabled makes no difference.

[PD3LK]

Is it still there when you disconnect/shorten antenna inputs?

[w9mdb]

Yes...still there.

But that did help to identify what appears to be the source at 4.953MHz
It's -85dBm but reduces a lot when enabling the 60M antenna connection.

[PD3LK]

nasty : ( i suspect it's coming from your (switching?) PSU.
Try another one or a battery as Scott advised.

[JJ4SDR]

Not a Thetis issue (moving the topic).

Have you tried a different power supply? Run the ANAN off of a battery? Run around the house turning off circuit breakers?

Scott!

Will try it. Right now I am using (my preference) a linear PSU by Astron. I have a SPS too.

Juha

[w9mdb]

I identified my problem...it is my 2nd Bodnar GPS sitting at 4.593 but it's creating harmonics like crazy which it seems should not happen.

Mike W9MDB

[w-u-2-o]

That's interesting, Mike. I have a mini-Bodnar, but it lives two stories above the main radio rack, and if it's throwing off any RFI it's not been apparent here. Is yours the full size or mini? And it's programmed to 4.593 MHz? That's kind of an odd freq?

[w9mdb]

MIne's plugged into the rig on Ant2....I use a programmable attenuator
I have 3 of them for doing different frequency testing across rigs and such.

That just happened to be the last frequency I was testing.
With 48dB attenuation it clears up a lot. Much less than that and the noise floor on the wideband display goes up dramatically.
So any signal over about -90dB is causing bad effects.


Mike

[w-u-2-o]

MIne's plugged into the rig on Ant2....I use a programmable attenuator. I have 3 of them for doing different frequency testing across rigs and such.

That just happened to be the last frequency I was testing. With 48dB attenuation it clears up a lot. Much less than that and the noise floor on the wideband display goes up dramatically. So any signal over about -90dB is causing bad effects.

The Bodnar units are not very good for such purposes if you are worried about harmonics. The output of the Bodnar units are square waves. So of course you are going to get odd-integer harmonic frequencies of the form 2π(2k − 1)f.

If you are concerned about harmonics in your experiments you should probably get a real signal generator that you can lock to the GPS reference. Or you could build low pass filters for the Bodnar for each frequency you want to use.

[JJ4SDR]

Not a Thetis issue (moving the topic).

Have you tried a different power supply? Run the ANAN off of a battery? Run around the house turning off circuit breakers?

Tried unplugging a few wall-warts but no difference. Then I looked at my YETI emergency power supply (I am supposed to keep in plugged in at all times) and decided to switch it off. All birdies or "spurs" gone.

Thanks!
Juha

[w-u-2-o]