In article ,
Gerald Rego wrote:

Hey everyone!

I was hoping someone has encountered one of these radios and can explain so
mething to me.

I am working on a transmit problem on a HR2510. The first step that is req
uired is to check the idle current on the MRF477. At present I am getting
O MA DC on the test points (removing the thin conductive board that slips b
etween them).

The sites I have been visiting says I should be getting 50 ma and to adj th
e pot till I get the 50 ma current.

Looking at the manual the MRF447 is suppose to have 13 volts on the collect
or.. which is there and zero volts on the emitter and base.

I am not understanding how I can get 50ma when I have zero volts on the Bas
e of the transistor? I do get a little bit of current when I push in the t
ransmit button but the instructions are pretty explicit that I should be in
the receive mode, AM and at 30MHZ.

I have already replaced the MRF447 as well as the driver to the MRF447.

Could someone explain the theory behind the circuit and how I am suppose to
get the 50ma on the test points?

Any help would be GREATLY APPRECIATED.


THANKS SO MUCH IN ADVANCE.

If you need to look at the schematic it is available

http://www.cbtricks.com/radios/uniden/hr_2510/

the procedure for aligning the radios transmit section is there as well.

Gerald-

Several years ago I attempted to do an alignment on a Uniden HR2600. I
found similar problems in the documentation, including a miswire in the
schematic!

Looking at your schematic Sheet 1, I see that DC bias for Q132 and
others, is supplied by the collector of Q125. It is possible that the
radio's logic switches this bias on in transmit mode, and off in receive
mode. If so, it may only be possible to adjust transmit bias in
transmit mode.

Q125 emitter is fed from the output of IC107. Judging by its part
number, this IC may be an 8 Volt DC regulator. I would measure voltage
on Q125 collector and see if it is low on receive and around 8 Volts on
transmit.

Fred
K4DII