Subject: OUTPUT POWER MODIFICATIONS FOR THE UNIDEN HR2510 & HR2600

  Uniden's HR2510 & HR2600 10 Meter Amateur radio's are nice
for single band operation, but a little more output power
is desirable for portable use.

CREDITS:
M.T. Stacey KC4HGH in Septembers issue of 73 Amateur Radio (1989)
Published his findings on power modifications to the HR2510.

The modifications that follow are based on his works with some additions:

INTRO:
The factory has the HR2510 & HR2600 output power levels set for
continuous duty. I.E. AM,FM & CW 10 Watts, SSB - 20/25 Watts.
The radio is capable of much more output power for intermittent operation
like SSB.

**************************** POWER MOD ********************************

  PROCEDURE                    HR2510             HR2600
-------------------------------------------------------------------------

Relocate capacitors to         C122,C116          C122,C116
bottom of Board. (This
is to allow spreading of
the tuned/trap output
coils.

Replace Pre-driver Tx
(2SC2086D) w/ ECG-340          Q124                Q34
(Note pinout change)
2510/2600's w/ the
2SC1973 device require
no pinout change.

Replace output Device
MRF477 w/ MRF497               Q132                Q32

Replace Bias current           R158                R158
limiting resistor from
82 ohms to 68 ohms
1/2 watt device.

Pull bias jumper board
out of the circuit.            PB100               PB100
Place a current meter
(100ma) between pins
TP2 and TP4

Adjust Final bias for
80-85 MA, USB position.        VR112               VR13
No Modulation.

Fire radio up with
power meter and 100W
dummy load attached.
Adjust ALC for Maximum.        VR104               VR5
1Khz tone is helpful.

Mode to AM/FM
Spread coils                   L121,L123           L14,L16
for maximum.

AM/FM power adjustment,
20 Watts is easily obtained.
I think 25/30 may be pushing
it in this Mode. (Melt Down.)
Adjust controls for your       VR103,VR107         VR4,VR8
desired levels.

*************************************************************************

 My experience in increased output levels are as follows: "SSB Mode."

HR2510 = 32 Watts RMS (1Khz Tone) / 45.2 Watts PEP

HR2600 = 37 Watts RMS (1Khz Tone) / 52.3 Watts PEP

The above measurements are made with Bird 43 into a 50 ohm load.

PARTS SOURCE:

PF PARTS INC.
1320 Grand Ave.
San Marcos CA. 92069
800-854-1927

73's    Paul   N2FAN