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Output modification for the HR2510

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Old 07-09-2011, 03:51 PM
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Default Output modification for the HR2510


The idea of this modification is to replace the Final Power transistor, Using Motorola MRF455 -
( Thanks to KB3CBS for the Info)

Please Note:
This is A way to replace the 'hard to get' original MRF477, while it is possible to get a little higher output, unless you have a damaged MRF 477, it is a substantial amount of work for this "slightly higher output",- about 40-50W SSB.


MRF477 and MRF455 is quite different!!!

- MRF477 vs. MRF455 Pinout -
These 'pinout' images illustrates the problem using the MRF455 transistor in replacement of the original MRF477,- You need to mount the MRF455 Transistor to the heat-sink and make connections to the pcb using tree short 'hookup' wires. See the illustration below.


MRF455 Hookup wires and HR2510 Main-PCB connections


HR2510 Heatsink with Final Transistor MRF455 Mounted

The image shows the HR2510 Heatsink with the MRF455 and hookup wires mounted on it,- I de-assembled the Heatsink to be able to drill the screw-holes to be able to mount the MRF455 transistor,- See the drill-diagram below.

- 2SC2086 vs. NTE-340 Pinout -

This mod also require`s that you replace the Pre-driver Transistor Q134, NOTE! the NTE340 use a different pin-out, simply turn the transistor 180 degrees when putting it in place.
Both transistors use the TO92 Case, But the NTE340 is named 'TO92 Giant' because it is a bit longer on the top.

Comparative Transistor data
Transistor Type Descriprion
NTE340 Si-NPN RF-Power/Tr, 86V, 500mA PQ=0,6W
2SC2086 Si-NPN RF-Power/Tr, 75V, 1A, PQ=0,45W(27Mhz)
- PROCEDURE -
Output power mod for the Uniden HR2510 & HR2600

Uniden's HR2510 & HR2600 10 Meter Amateur radio's are nice for single band operation.

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.

************************* 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 Q134 Q34
(Note pinout change)
2510/2600's w/ the
2SC1973 device require
no pinout change.

Replace output Transistor
Q133 the MRF477 w/ MRF455
use short hookup vires as
described above 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 between pins
TP2 and TP4

Adjust Final bias for
80-85 MA, USB position.
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 AVG (1Khz Tone) / 45.2 Watts PEP
HR2600 = 37 Watts AVG (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

Thanks to KB3CBS for the Info for this Mod
Attached Images
File Type: jpg hr2510_pinout477.jpg (3.4 KB, 229 views)
File Type: jpg hr2510_pinout455.jpg (7.1 KB, 224 views)
File Type: jpg hr2510_heatsink.jpg (18.4 KB, 227 views)
File Type: jpg hr2510_nte340.jpg (3.6 KB, 226 views)
File Type: jpg hr2510_2sc2086.jpg (3.3 KB, 227 views)
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  #2  
Old 07-09-2011, 03:53 PM
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Default Hook Up Diagram

The Hook up Diagram for the above Mod
Attached Images
File Type: jpg hr2510_hookup.jpg (37.3 KB, 230 views)
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I turned to look but it was gone
I cannot put my finger on it now
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The dream is gone.
but I have become comfortably numb.

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Old 07-09-2011, 06:19 PM
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Default

I often thought about doing this aswell its a cool mod.
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