LNK Receiver Preamp

You can hear the weak ones, too, and without spending a fortune!

No need to spend $110 or more for a good, low-noise FET preamp! Our LNK-( ) Preamp is only $79,wired/tested. Unlike other FET preamps on the market, this one uses one of the new-generation, very-low-noise, dual-gate MOS FET's which are designed exclusively for use in the vhf & uhf bands. They have built-in diode protection and very low feedback capacitance, resulting in good stability and rugged performance under a wide range of voltage, signal, and load impedance conditions. Note that there is a recent trend to use silicon rather than gallium arsenide at vhf and uhf frequencies. New techniques provide better noise figure than we got with comparable GaAs FET's only a few years ago.

Some units you may see on the market use triode fet's designed for microwave, and they are not always stable when operating at vhf and uhf frequencies. Most don't have any built in diode protection; so they must be handled very carefully. Some companies even use bipolor transistors, which are cheap but notorious for intermod. The FET's used here are designed exclusively for use at these frequencies; so they don't easily oscillate. And replacement fet's are relatively inexpensive.

Surface mount technology is used to obtain minimum noise figure and best stability.

The preamp is connected in series between the antenna and the receiver to effectively lower the noise figure of the receiver front end, allowing weaker signals to be received. The LNK series was designed for operation in 50 ohm systems; however, they will operate satisfactorily on 75 ohms as well.

FEATURES:

Small Size: only 1-1/2 x 3-1/2 x 1-1/8 in. high (plus connectors)
Easily mounts inside shack or up on tower (receive only applications).
Low noise figure to hear weak signals.
Rugged, diode-protected, new-generation dual-gate silicon FET's.
Wide dynamic range for overload resistance. (1dB compression @ +5dBm)
Easy to tune
Operates on +12 to +15Vdc @ 10mA; no special power supply required.
BNC input/output connectors for easy connection. (sorry, cannot change to N connectors)
Power on hookup wire (24" supplied), using coax shield for ground.
Shipping weight 1 lb

MODEL	TUNES RANGE	FACTORY PEAKED	TYP. NOISE FIGURE	GAIN	MIN. 3DB BANDWIDTH
LNK-50	35-63 MHz	52 MHz	0.6 dB	24 dB	±3 MHz
LNK-100	88-108 MHz	100 MHz	0.6 dB	22 dB	±5 MHz
LNK-120	108-140 MHz	120 MHz	0.6 dB	22 dB	±4 MHz
LNK-137	130-160 MHz *	137.5 MHz	0.6 dB	18 dB	±4 MHz
LNK-146	130-160 MHz *	146 MHz	0.6 dB	18 dB	±4 MHz
LNK-166	150-180 MHz	166 MHz	0.6 dB	16 dB	±5 MHz
LNK-220	195-240 MHz	224 MHz	0.7 dB	18 dB	±5 MHz
LNK-400	360-440 MHz	400 MHz	0.8 dB	19 dB	±5 MHz
LNK-450	400-470 MHz	448 MHz	0.8 dB	18 dB	±5 MHz
Note: Units are easily repeaked at your operating frequency after installation. They are stocked tuned to center frequency indicated above. If you prefer, we can custom tune to your frequency at an additional charge of $10. However, if your operating frequency is within 2-3 MHz of the center frequency specified, special tuning is unnecessary. * LNK-137 and LNK-146 are same unit, just tuned differently.

PRICES:

LNK-( ) Preamp, wired/tested ...$79.00 (specify model from chart above)

Tuning charge if you want it tuned to custom frequency ...$10

A40 AC adapter ...$9.50

PF-1 Phantom Power Kit option ...$5.00
Often, we are asked if the +12Vdc power for the preamp can be fed up the coax cable from the receiver for installations where the preamp is mounted at the antenna. We have long resisted the temptation to try to save a few cents on some light-weight hookup wire by using this trick, feeling that chances of messing up the rf performance are too great.
We now offer a kit for those who want to try this anyway. It consists of the rf chokes and dc-blocking capacitors needed for both ends of the cable, at the receiver and the preamp, along with general instructions. It may be used on any frequency from 130-500 MHz.

WHEN IS A PREAMP BENEFICIAL?

It is tempting to hope that a preamp can make any receiver more sensitive, in any situation. But, it is important to understand what happens when you add a preamp before a receiver.

A preamp can help overcome a deficiency in receiver sensitivity only if the noise figure is poor, either due to the design or because a lossy filter or cable adds to the noise figure. For instance, a preamp up at the antenna can overcome the effects of coax cable loss.

However, adding gain in the front end raises all signal levels; so, in effect, every dB of gain added overrides one dB of if selectivity or dynamic range. Therefore, adding a preamp can result in intermod or desense. The only way to know is to try it.

See what customers have to say...

Wow, I purchased the 166 MHz preamp and am totally thrilled with its performance! I set up a 'T' connector with the antenna so that amplified signal would go into one radio and non-amplified signals go into the other. It was crystal clear how much improvement the amp makes! ... Josh O.