Tag: 0dbm

How far does 1mW go ?

Do you remember playing as a kid with the short range 49 MHz walkie-talkies ?

49MHZ_1_Walkie_Talkies

49 MHz Walkie – Talkies

We used to play with these often as a kid, and the range was shorter than your voice ! With an output between 5 and 50 mW these could often struggle to communicate more than a few meters.

Still the fun we had trying to extend the range.

The Elad FDM-DUO has a 0 dBm o/p on the rear that will provide 1mW out from 100 khz to 156 MHz

 

The Elad uses a SMA female connector on its rear, and using a ebay special connector I routed this into my ATU and doublet antenna matched for 7 MHz. I wanted to run WSPR at 1mW and see what decodes I could achieve.

Over the course of the next couple of days I ran the Elad both at night and during the day. It was hard to achieve any decodes at night, but in the day I was decoded on many occasions from stations in the range of 50 to 770 KM.

Best DX was 2 spots by Denmark based station 5P1B at 770 KM.

The following statistics provided by WSPR.net database

 

 Stations who decoded M0TAZ v Signal @ 1mWsignal m0taz

Stations who decoded M0TAZ v Distance @ 1mW

decoded m0taz

 

You can download the free WSPR software provided by K1JT online. WSPR reports are uploaded and databased online.

73 Dave M0TAZ

0dBm 1mw input – Wideband Amplifier

Adventures of a broadband amplifier.

Updated product 1 to 930 MHz amplifier 2w

These products often change, you can view a similar one here

Some radios are equipped with a 0dBm (1mW) output that can be used to drive an amplifier. The advantage of this output is it usually works over the entire transceiver range. So you can often obtain 1mw from 10 kHz to 60 MHz.

I recently read an article in Radcom from Dave Pick G3YXM and he had purchased an amplifier from eBay. Dave confirmed it was this model with an operating frequency range from 1 to 500 MHz.

Like this one using the search term ” 1MHz – 500MHZ New HF FM VHF UHF RF Power Amplifier For Ham Radio + Heatsink”. If you wanted to use this below 1 MHz that’s possible but you will need to swap the inductors for larger values.

Tests without any changes showed 1mW in @ 1.9 Mhz = 1.6w out. The power out seems to drop to 100 mw below about 500 Khz. I also tested the amplifier at 144 Mhz and the o/p was around 1w.

Hopefully, with a few changes, this will allow me to run a small amount of power on 472 Khz WSPR.

1mw amp 1mw amp 2