The LP-Pan has an AD 8007 input amplifier, the same amplifier I use in the Z10000 buffer amp.
In the LP-Pan, the AD8007's gain is set by a combination of fixed resistors and a potentiometer. Quickly working through the numbers, varying the potentiometer from one end to the other results in gain ranging from +6 dB to +15 dB, net of the 6 dB loss in the series 49.9 ohm resistor. (Measured at the AD8007's output pin, the gain is 6 dB above these values, but in order to drive a capacitive load, a series 49.9 ohm resistor is added between the output pin and the load. This results in 6 dB loss if the load is 50 ohms.) The main reason one might wish to apply the buffer modification to the K3 instead of cranking up the LP-Pan gain or purchasing one of my Z10000 buffer amplifiers is that a somewhat improved noise figure will result if the K3's IF output follower loss is reduced. In practice, the improvement in noise figure is not huge as the overall NF is set mostly by the early gain stages in the K3. Jack K8ZOA On 1/7/2010 12:32 PM, Bill W4ZV wrote: > > > Bill W4ZV wrote: > >> An unmodified K3's IF OUT has 7-17 dB transfer loss that cannot be >> compensated for in ANY panadaptor, so the mod is necessary for the P3. >> >> http://cliftonlaboratories.com/elecraft_k3_and_panadapters.htm#What_then_is_the_transfer_gain_of_the_K3_ >> >> > Jack Smith's comment on the page above "Telepostinc's LP-PAN has a built-in > amplifier to overcome the transfer gain problem." is incorrect. LP-PAN > **DOES** require the mod and N8LP posted a mod similar to Elecraft's back in > July 2008. > > http://groups.yahoo.com/group/LP-PAN/files/K3_Buffer_Mod/ > > 73, Bill > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
