[Elecraft] XV Series Transverter to TS-850

[Martin]

Hello elecrafters,

a guy from the topband-reflector asked me to post this to the
elecraft-list.

--- Duane Grotophorst <n9dg at yahoo.com wrote:
 
 
 Or another approach is to build an external
 attenuator that can handle 20W or so for the TX side. Then use
 a separate RX IF line to the typical RX antenna of the
 HF radio. I have been doing this with good success
 with my Ten Tec Pegasus/Corsair radios for some time
 now. I use DEMI transverters for 50-432Mhz at the
 ~100mw drive level. The attenuators that I'm using I
 built myself from Vectronics 300W dry dummy loads. I
 drilled a hole below the SO239 connector and then
 added a BNC connector. Internally I built a "PI"
 section attenuator with the 50 load as the input
 leg, the other two resistors were 1/2W, I don't remember
 the R-values of them off the top of my head but they
 were from the ARRL Handbook. I started with 300W
 dummy loads to accommodate high duty cycle modes like WSJT
 to hopefully avoid having my attenuation value
 change during long transmissions.
 
 I build these attenuators to provide ~20dB of
 attenuation, the exact value wasn't critical since
 the DEMI transverters have 25-dB adjustment range of
 their own. In the case of the Elecraft XV transverters
 they can accommodate a few watts of input drive so the
 level of attenuation could be some less (would
 probably need higher wattage resistors for the other
 2 sections of the PI in this case). I decided to go
 this route because it allowed me to avoid having to dig
 around inside the radio for low level TX signals it
 also offered more versatility if I ever want use a
 different radio as the IF without having to modify
 it first. Another advantage is that the worst case
 overdrive with a 100W radio would only be about
 6-7dB, it may sound like garbage but the transverter should
 survive such a mishap. I never liked depending on
 ALC schemes or panel settings alone to keep me from
 blasting the transverter with 100W of drive. Also by
 using ~20W drive level the broadband TX noise of the
 100W PA is also attenuated by the attenuator, with
 an ALC based scheme that would not be the case, so I
 believe this approach provides cleaner drive.
 Obviously a low-level IF output from the IF radio is
 the best if it's readily available, but that isn't
 always the case.
 
 Duane
 N9DG
 
 Grid EN53bj


-- 
Best regards,
 Martin
K2 #2706                          mailto:dl1iaq at gdxf.de