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
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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
From: [email protected] <[email protected]> on behalf of Raj vu2zap <rajendrakumargg@...>
Sent: Thursday, October 25, 2018 12:59 AM
To: [email protected]
Subject: Re: [BITX20] Harmonics and Relay Replacement
?
The before relay pic has slightly degraded performance due to the relays being mounted on
sockets. This add a few mm extra length to the leads to the contact and increases coupling!
The second is Axicom soldered directly on PCB.
With Axicom my boards are perfect on 40 and 80.
Raj
At 24-10-18, you wrote:
That's pretty impressive, Raj.
Jack, W8TEE
On Wednesday, October 24, 2018, 1:06:11 AM EDT, Raj vu2zap <rajendrakumargg@...> wrote:
Jim,
I did? not get much improvement with Axicom in a socket.. soldering directly to board made a big difference.
The harmonic rejection on lower bands was amazing!
On one board only 20M is a bit off.
Raj
Example: the first is stock and 2nd is Axicom. The second needs to be referenced to -1db to compare to
first!
?
?
At 23-10-18, you wrote:
No, I just used the relays.? I was looking for the simplest approach.? I have several other projects that were on hold, giving me time to try the relay swap Mike Doty originally discovered with limited but encouraging
results.?
I've done all I plan on doing regarding the harmonic reduction.? I shared what I found with the group, got unjustly accused of being a "phoney" and I now wash my hands of this part of the project.
Back to improving the available firmware, displays and controller hardware.?
Jim
