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LP-PAN Preamp Kit

Ordering...

Important note about the Preamp Kit:

This kit is is provided mainly for K3 owners who want to improve the noise flloor of the panadapter display to allow seeing weaker signals. The addition of a low noise preamp ahead of LP-PAN compensates for the relatively lossy IF buffer amplifier in the K3. This problem is compounded when you add a P3 between the K3 and LP-PAN since the hybrid splitter in the P3 adds another 3dB of loss. This is especially important when the K3 preamp is off.  No tests have been run with other brands of radio to determine if the preamp would improve overall noise floor.

Addition of the LP-PAN preamp lowers the displayed noise floor by about 6-8dB over a stock LP-PAN when the K3 preamp is ON and 8-10dB when the K3 preamp is OFF. This assumes that the stock LP-PAN has its gain pot set to maximum gain (the factory default setting).

Lowest noise floor is achieved with the LP-PAN preamp installed and LP-PAN gain pot at maximum, but this will reduce dynamic range by about 10dB. Setting the LP-PAN gain pot to minimum will add a couple dB to the noise floor, but improve dynamic range by 10dB. This is the recommended setting to start with. A front panel attenuator switch was added to prevent possible overload in case the user wants to run LP-PAN at maximum gain. The kit can be installed without drilling a hole in the front panel for the switch if desired. In this case, simply don't install the keycap on the switch. The switch, in the no attenuation position will still fit behind the front panel if the keycap is not installed. Most users will probably find that the attenuation is not needed.



Below is a picture of the assembled preamp board.

To the right is a picture installed in LP-PAN.

  

Installation requires the addition of a standoff, soldering two coax jumpers to existing pads on the main PCB, cutting one PCB trace and addition of a lead for 12V power. Optionally, a hole can be drilled or punched in the front panel if the user wishes to use the attenuator switch. If the keycap is not installed on the switch, it will fit behind the front panel with the attenuator in the OFF position.



The kit includes...

* PCB w/pre-mounted SMT
* DPDT Switch & Keycap
* 3/8" Standoff
* Regulator chip
* (2) 0.1uF caps
* (2) 0.01uF caps
* (4) 96.2 ohm 1/8W resistors
* (2) 71.2 ohm 1/8W resistors

* (1) 56.3 ohm 1/2W resistor
* 1N4148 Diode

Not shown:
RG-316/U Teflon coax
#26 hookup wire
Lockwasher
Attenuator label


Assembly manual...

Manual available here.


Specifications...

(Standalone LP-PAN gain set to minimum, E-MU 0202: 96kHz sampling rate, E-MU gain pot at 10 o'clock)

Preamp gain...................................................... 12-14dB
Preamp NF............................................................. 2.7dB
Reverse Isolation..................................................... 35dB
LP-PAN NF w/preamp.............................................. 7dB

(LP-PAN with K3, gain set to minimum, E-MU 0202: 96kHz sampling rate, E-MU gain pot at 10 o'clock, K3 preamp ON)

Noise floor w/preamp (PowerSDR/IF)...........  -143dBm
Clipping point w/preamp (PowerSDR/IF).......   -28dBm

Noise floor and clipping levels depend on sound card, K3 preamp state, sampling rate, sound card input level setting and LP-PAN gain pot setting. These specs apply only to the conditions noted above
.



Pricing and Ordering for US customers...

The LP-PAN Preamp will be offered as a user installed kit or a factory installed option. Kit assembly and installation time for a typical user is about 1-2 hours, depending on the user's skill and whether he opts to add the front panel hole and label. The Preamp Kit costs $25 plus shipping ($2 for 1st Class, $5 for Priority Mail). The preamp can also be ordered installed in a new LP-PAN. See the LP-PAN page for ordering with LP-PAN.
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LP-PAN Preamp kit with 1st Class shipping to US...


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LP-PAN Preamp kit with Priority Mail shipping to US...

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Pricing and Ordering for overseas customers...

NOTICE: The 1st Class Airmail and Priority Mail shipping of these small packages is NOT insured.

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LP-PAN Preamp kit ($26USD) with 1st Class shipping to Canada or Mexico ($4USD).

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LP-PAN Preamp kit ($26USD) with Priority Mail shipping to Canada or Mexico ($8USD)...

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LP-PAN Preamp kit ($26USD) with 1st Class shipping outside North America ($8USD)...

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LP-PAN Preamp kit ($26USD) with Priority Mail shipping outside North America ($13USD)...

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Email us for questions.


73,
Larry N8LP

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