Hi readers.
I have just written TT regarding my Omni V which is FM'ing, and received the
following reply:
Q:
"I have also found that the radio is FM'ing on TX, the problem being worse on
the lower bands 160/80m where it FM's approx 500Hz between min and max RF out.
I don't have a TEN-TEC PSU, but the unit in use is substantial and can supply
25A continuously and is RF hardened..other radios work fine with it.
The PSU exhibits approx 60mV change in output voltage when in tune mode and
varying the RF out from min to max into a dummy load or real antenna.
Any pointers on the problem?"
A:
The FM is probably caused by the high ripple (60 mv) from the power supply. The
supply should have less than 10 mv of ripple.
I have not responded to TT regarding this, thought I'd ask here first.
Has anyone else experienced the same problem?
As stated above, the PSU output voltage does droop by 50-60mV when the radio is
in tune mode and the RF output is wound right up. There is very little
hum/noise/ripple on the PSU output..in the order of 15mV P-P of junk is
observable on the 'scope.
Surely the radio shouldn't be this sensitive to small voltage drops etc? What
about those that use it mobile powered from the car electrical system, not
usually the quietest or most stable supply?
All input appreciated!
And yes, I am going to try a car battery in place of the PSU.
I haven't measured the voltage drop down the TT supplied power cable, but I'd
bet it's more than 10mV at 18+ amps at full power!
73 all.. Paul MW0CDO
--- StripMime Report -- processed MIME parts ---
multipart/alternative
text/plain (text body -- kept)
text/html
---
|