Gene,
Change the relays for sure. 3 axicom will do for KT1,2,3
With relay change the spurs decrease with lower 3rd 5th harmonics. You
can change L5/7... they are same as
original values or close to. You have to replace them exactly to what was
shown earlier.
The one I used is 1210 680nH a yellow one from EPCOS / TDK shielded.
Others wont work..
The mod is to reduce spurs. L5/7 is optional, relays you MUST
change.
Raj
At 02-11-18, you wrote:
toggle quoted message
Show quoted text
HI Raj,
Thanks for the info, I have the relays on order.
Should I also change L5/7 at the same time?? (Exactly what is the
L5/7 Change?, Is it a value change or just convert to SMT?)
Gene N2IJF
From: [email protected]
<[email protected]> on behalf of Raj vu2zap
<rajendrakumargg@...>
Sent: Thursday, November 1, 2018 1:25 AM
To: [email protected]
Subject: Re: [BITX20] Harmonics and Relay Replacement
?
Hi Gene,
There is no final solution.
So far my conclusions... the harmonics floating around the board is the
cause of the spurs.
Changing the L5/7 reduced the spurs but not the cause which is
harmonics.
Changing 3 relays KT1/2/3 reduces the harmonics dramatically specially on
lower bands.
Lower bands 40/80 can be driven higher without crossing the red
line!
Keep the drive/mic level at where you get 10W on 40M and you should be
kosher
without SMD coils on higher bands.
If you over drive the uBitx on higher bands then you will be in the
red!
Some boards behave a bit different, relays are a good simple mod bet for
now.
Raj
At 01-11-18, you wrote:
Sorry to ask but I been offline
for a few weeks and the subject seems to have died out (after reading
past posts).? So is there a final solution for the spurs/harmonics
for the V3 uBitX?
- Axicom replacements (soldered directly to PWB)?
- Axicom replacements with SMD inductors?
- K5BCQ uBITX Relay Switched LPF/BPF board?
I have an unbuilt V3 that I am not sure if I should even
complete.? I want to be legal but do not have a lot of test
equipment so verification will be difficult.
Thanks,
Gene N2IJF
Raj vu2zap