[Elecraft] XV50 on 70MHz

[Allan Duncan]

Hi,

Here are my component values I used to convert my XV50 to 70MHz. 

I have included the Mouser part numbers but, as previously discussed, some
parts now have huge minimum order quantities. Don W3FPR mentioned that could
be because they have been replaced by a ROHS compliant part. I have not been
able to find that replacement part in their PDF catalogue but I suspect Don
is correct.



							Mouser Part No.

C42 & C43  47pF					80-C1206C470J5G

C44  100pF						80-C1206C101J5G

L1  5.5 turn inductor 				434-1012-5.5C

L10 & L11 4.5 turn inductor			434-0712-4.5C

L12, L13 & L14 4.5 turn shld inductor	434-1012-5.5CS

With L1 changed to the value stated, C1 seems to align around its midpoint.

I also changed Q1 to an MPS918 and changed the circuit to be the same as the
LO circuit in the XV144 but with C12 10pF, C14 47pF. This removes the
ability to frequency calibrate the LO but as I use the transverter with my
K2 I can correct any error in the K2 firmware in a similar way to the XV144

I took the view that the filter on the output of the LO is only fitted to
the XV50 as the 2nd harmonic of the 22Mhz is 44MHz and a bit close to 50MHz.
With a 42MHz LO the 84MHz is far enough away not to get through RF bandpass
filter (L12, L13, L14, C45, C46 etc). So I omitted C59, C58 and L3. I will
recheck the TX spurious sometime - it would be easy to retrofit those
components.

I understand that the new XV50 kits contain the RA30H0608M (70MHz) module in
place of the M57735 which simplifies the modifications significantly so I
have not included those details here.

The modifications are really fairly trivial. The only tricky bit is changing
the SMD capacitors C42, C43 and C44. This needs a steady hand.

I guess that if the crew at Aptos had more time it would be possible to
offer an official XV70. If nothing else, it would be nice to have a "XV70"
LED indicator label for the front panel!

I am very pleased with the performance of my XV50 on 70MHz - maybe I need to
consider a getting a K3 to use with it as well?

73

Allan 
GM4ZUK