Tuesday, February 23, 2016

Baofeng Tech UV-2501: 220 Relay Noise

I was playing with the dual watch/TDR functionality and 220 on the UV-2501+220. I noticed this sound (video):

"Radio is sturdily constructed and amazingly small. Programmed it with the software from the miklor site and tried it out on my comet triband antenna on local repeaters in all 3 bands. Good audio reports although was noted as slightly muffled on highs. Power output is around 20 watts or a few under.
One odd behavior I did notice is TDR enabled or scanning from UHF/VHF to 220 results in relay noise.
Side a/side b noise (TDR on) 
Uhf/uhf no 
Vhf/vhf no 
Uhf/vhf no 
220/220 no 
Uhf/220 yes 
Vhf/220 yes"

"I suspect the 220 MHz band antenna lowpass filter is switched with a relay and the 2 meter lowpass filter and 70 cm highpass filters are switched with PIN diodes. A relay that completely isolated the 220 MHz RF filter is easier to do this than design a more complicated bandpass filter and the relay likely has less insertion loss and won't impact the RF performance of the 2 meter/70 cm bands. Based on that I would say the sound you are hearing is normal."
I e-mailed the Baofeng Tech guys and they confirmed this is normal behavior for the dual watch flipping between 440 or 2M and 220.

1 comment:

  1. Some of the old ham equipment loaned to me when I was a baby Technician had mechanical relays in it for T/R. Makes me kinda nostalgic. ::tears::