Grappling with RF modulator and HDHomeRun

itm · 14-10-2023, 10:53

I use a HDHomeRun to make my Freeview channels available for viewing on Android devices around the house. It's been working well, but I've just thrown a spanner into the works by introducing an RF modulator into the loop (to allow me to watch an additional HDMI-connected device using the same method).
The RF modulator is interfering with the main TV signal, so that the HDHomeRun is now only able to detect around 20% of the available channels (and none of the HD channels). This is the model that I have:
https://tdigroup.co.uk/product/technoma ... modulator/

The guys at HDHomeRun support have told me that "something is generating an extremely strong signal at 48MHz to the point that spikes from the harmonics are visible at every multiple of 48 up to 768MHz".
That sounds like the RF modulator, as I currently have it set to operate on channel 21 (474MHz). I have tried switching the RF modulator to other channels (27, 43, 69), and also tried reducing its output by -5db, but it doesn't seem to help.
I was wondering whether any RF signal gurus could advise on how best to fix this?

My terrestrial TV signal is currently delivered from Crystal Palace, over these channels I believe:
22 482MHz
23 490MHz
25 506MHz
26 514MHz
28 530MHz
30 546MHz

itm · 15-10-2023, 13:03

Answering my own question...I found an old attenuator lying around in a drawer, and fitted it between the RF modulator and the HDHomeRun. Problem solved!

**Paul** · 15-10-2023, 16:21

Well its good to hear you fixed it.

**Chris** · 15-10-2023, 18:43

Who just has an old attenuator sitting around in a drawer?

. I’ve been DIY’ing my own home for getting on 25 years and I have tons of random crud in drawers and boxes all over the place, but so far I’ve never collected (or used) an attenuator…

**Paul** · 15-10-2023, 18:55

I had one for many years, from my NTL broadband, after it was determined as no longer being needed. I finally threw it away earlier this year.

**Chris** · 15-10-2023, 19:28

Quote:

Originally Posted by Paul

I had one for many years, from my NTL broadband, after it was determined as no longer being needed. I finally threw it away earlier this year.

Which means you can absolutely guarantee you’re going to need it in the next 6 months

Jaymoss · 15-10-2023, 19:52

I have a few of them lying about somewhere. Finding them would not be so easy haha

itm · 15-10-2023, 20:56

Believe it or not, there were 2 attenuators in the same drawer. It's knowing where these things are that's the challenge LOL