Topics

Harmonics and Relay Replacement

Mike Doty
 

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

Jack Purdum
 

Mike:

I'm a software guy and am a bag of hammers when it comes to the EE stuff, but this is very interesting to me, since we have so many people who are worried about the harmonics. Thanks for the post!!

Jack, W8TEE-

On Monday, October 8, 2018, 3:54:16 PM EDT, Mike Doty via Groups.Io <mikedoty@...> wrote:


I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

Mike Doty
 

Thanks Jack.  I wish I could say that I discovered this intentionally but, to be honest, it was completely accidental.  I had removed the original relays from my first uBiTX while looking for a solution to the harmonics issue.  In doing so, I broke a pin on one of the original relays.  I had some of the Axicom relays in the junk box so I ended up sticking those in as replacements for all 5 of the relays.  When I put things back together and looked at the output I saw that the harmonics were all down below -50dB.  I still had 4 of the Axicom relays left in the junk box so I replaced the 4 relays on my second Ver 3 rig, leaving K1 in place.  I saw the same results.  To be sure that there wasn't something else involved before posting to the group, I ordered more relays and replaced the same 4 relays in my Ver 4 uBiTX.  Again, the same results.  I've attached pictures of the spectrum analyzer results for both of my Ver 3 rigs so you can see that it wasn't just coincidental. Unfortunately I didn't take pictures of the other two rigs before replacing the relays but they both originally had harmonics around -35dB before the relay swaps.  All of the spectrum analyzer results for each rig shown are on 40 meters at 10 watts with the SA span from 1 MHz to 100MHz but I cannot see any harmonics above -50dB on any band, 80 - 10. 
--73-- Mike

Clark Martin
 

What fundamental frequency was this for and have you tested other bands?  This is good news, thank you for trying it.

Clark Martin
KK6ISP

On Oct 8, 2018, at 12:53 PM, Mike Doty via Groups.Io <mikedoty@...> wrote:

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.

Gordon Gibby
 

Wow great work Mike!


On Oct 8, 2018, at 15:54, Mike Doty via Groups.Io <mikedoty@...> wrote:

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE
<v4_1 spec.jpg>
<v4_1 axicom spec.jpg>

Jim Sheldon
 

I sent Mike a private email asking if these were pin for pin compatible.  While waiting for an answer I did some more research and find they ARE pin for pin.  They are also available at Digi-Key under the part# PB1055-ND for a couple of pennies less plus a bit cheaper shipping.  They are $2.81 each singly and $2.633 apiece in quantities of 10 each (enough to replace all 5 relays in 2 radios for $26.33 plus shipping.

I ordered 10 of them from Digi-Key and will replace all 5 relays in both of my V4 boards.  I'll run spectrum analysis on mine once I get that done and hopefully will duplicate Mike's indications.  Might be the simplest fix at least for the harmonic problem anyway.  Since I operate only CW, I'm not concerned with the SSB spurs anyway.

BTW, right now, both my V4 boards DO meet FCC spec with all harmonics -45 to -48 dBC on both boards.  I have NOT adjusted the factory set PA bias or the power controls as prior experience showed me that doing so was a great way to get the rig out of spec for sure.  

After changing the relays I'll do a complete bias adjustment on the PA transistors per the HF signals website instructions and check harmonics again.  If they are still in spec after that I'll play around with the power control while watching the spectrum analyzer to see what, if any changes occur.

I was recently given the use of an IFR A-8000 spectrum analyzer that was calibrated less than a month ago so I think the tests will be pretty accurate (after I learn how to use the beast! - LOL)

Jim Sheldon, W0EB

------ Original Message ------
From: "Mike Doty via Groups.Io" <mikedoty@...>
Sent: 10/8/2018 2:53:49 PM
Subject: [BITX20] Harmonics and Relay Replacement

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

iz oos
 

That's unbelievable! Wasn't the bad board layout causing it? Do the new version 4 have different relays and/or a different board layout?


Il 08/ott/2018 23:18, "Jim Sheldon" <w0eb@...> ha scritto:
I sent Mike a private email asking if these were pin for pin compatible.  While waiting for an answer I did some more research and find they ARE pin for pin.  They are also available at Digi-Key under the part# PB1055-ND for a couple of pennies less plus a bit cheaper shipping.  They are $2.81 each singly and $2.633 apiece in quantities of 10 each (enough to replace all 5 relays in 2 radios for $26.33 plus shipping.

I ordered 10 of them from Digi-Key and will replace all 5 relays in both of my V4 boards.  I'll run spectrum analysis on mine once I get that done and hopefully will duplicate Mike's indications.  Might be the simplest fix at least for the harmonic problem anyway.  Since I operate only CW, I'm not concerned with the SSB spurs anyway.

BTW, right now, both my V4 boards DO meet FCC spec with all harmonics -45 to -48 dBC on both boards.  I have NOT adjusted the factory set PA bias or the power controls as prior experience showed me that doing so was a great way to get the rig out of spec for sure.  

After changing the relays I'll do a complete bias adjustment on the PA transistors per the HF signals website instructions and check harmonics again.  If they are still in spec after that I'll play around with the power control while watching the spectrum analyzer to see what, if any changes occur.

I was recently given the use of an IFR A-8000 spectrum analyzer that was calibrated less than a month ago so I think the tests will be pretty accurate (after I learn how to use the beast! - LOL)

Jim Sheldon, W0EB

------ Original Message ------
From: "Mike Doty via Groups.Io" <mikedoty@...>
Sent: 10/8/2018 2:53:49 PM
Subject: [BITX20] Harmonics and Relay Replacement

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE

Joe Puma
 

Mike this sounds promising. Thanks for the work and feedback. 

Joe




On Oct 8, 2018, at 4:51 PM, Gordon Gibby <ggibby@...> wrote:

Wow great work Mike!


On Oct 8, 2018, at 15:54, Mike Doty via Groups.Io <mikedoty@...> wrote:

I thought I would pass this along, for whatever it is worth.  I have two Ver 3 and one Ver 4 uBiTX rigs.  I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.  This may be anecdotal but with 3 rigs showing the same results it may be something to consider.  I purchased the relays from Mouser - part # 655-V23105A5403A201.  Cost was $2.89 per relay plus shipping.  I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--  Mike  --  W0MNE
<v4_1 spec.jpg>
<v4_1 axicom spec.jpg>

Glenn
 

Kees T
 

I measured about 2pF across the N/O and N/C contacts (when open) and about 4-5pF from the relay armature to the coil, just like the datasheet mentions for that relay. The relays I tested were the same type "16 pin" relay of various brands, who knows who actually manufactured them. 

A drop of 15dB is surprisingly high for one brand. Since you measured that LPF on 40m, what do other bands show ?

I would set the RBW to 100KHz or 300KHz

73 Kees K5BCQ 

Howard Fidel
 

Mike:
That is a great find! It means the capacitance is lower on those relays.

Howard

On 10/8/2018 4:22 PM, Mike Doty via Groups.Io wrote:
Thanks Jack.  I wish I could say that I discovered this intentionally but, to be honest, it was completely accidental.  I had removed the original relays from my first uBiTX while looking for a solution to the harmonics issue.  In doing so, I broke a pin on one of the original relays.  I had some of the Axicom relays in the junk box so I ended up sticking those in as replacements for all 5 of the relays.  When I put things back together and looked at the output I saw that the harmonics were all down below -50dB.  I still had 4 of the Axicom relays left in the junk box so I replaced the 4 relays on my second Ver 3 rig, leaving K1 in place.  I saw the same results.  To be sure that there wasn't something else involved before posting to the group, I ordered more relays and replaced the same 4 relays in my Ver 4 uBiTX.  Again, the same results.  I've attached pictures of the spectrum analyzer results for both of my Ver 3 rigs so you can see that it wasn't just coincidental. Unfortunately I didn't take pictures of the other two rigs before replacing the relays but they both originally had harmonics around -35dB before the relay swaps.  All of the spectrum analyzer results for each rig shown are on 40 meters at 10 watts with the SA span from 1 MHz to 100MHz but I cannot see any harmonics above -50dB on any band, 80 - 10. 
--73-- Mike


Mike Doty
 

Good evening Kees,
As I said in an earlier post, with the Axicom relays installed in 3 different rigs, I am not seeing any harmonic greater than -50dBm on any band from 80 thru 10 mtrs.  I have fuzzy pictures of the SA results for each band but I didn't want to take up server space posting them here.  I can make them available to anyone that wants them but the files are large.

Looking at the 3 rigs I have I found two different brands of relays installed, Hongfa and Virtual.  Readingt the datasheets for both brands and the Axicom relays the only difference I can see in the specs presented is a difference in coil resistance.  Notably though, neither datasheet for the installed brands gives a spec for RF isolation which makes me wonder whether they are actually rated for RF usage.  The datasheet for the Axicom indicates -39dB at 100 MHz.  I can't think of any other explanation for the results I'm getting but, as I also said in an earlier post, these are MY results that I have passed along for consideration.  For me, I'm satisfied with what I'm seeing.

--72-- Mike --  W0MNE

Dr. Flywheel
 

Regarding the relay spec differences, can anyone open the case of the "good" and the "bad" and take photos of the innards? It would be instructive to all of us to understand how to choose relays for future applications.

--Ron    N7FTZ

On Mon, Oct 8, 2018 at 9:38 PM Mike Doty via Groups.Io <mikedoty=reagan.com@groups.io> wrote:
Good evening Kees,
As I said in an earlier post, with the Axicom relays installed in 3 different rigs, I am not seeing any harmonic greater than -50dBm on any band from 80 thru 10 mtrs.  I have fuzzy pictures of the SA results for each band but I didn't want to take up server space posting them here.  I can make them available to anyone that wants them but the files are large.

Looking at the 3 rigs I have I found two different brands of relays installed, Hongfa and Virtual.  Readingt the datasheets for both brands and the Axicom relays the only difference I can see in the specs presented is a difference in coil resistance.  Notably though, neither datasheet for the installed brands gives a spec for RF isolation which makes me wonder whether they are actually rated for RF usage.  The datasheet for the Axicom indicates -39dB at 100 MHz.  I can't think of any other explanation for the results I'm getting but, as I also said in an earlier post, these are MY results that I have passed along for consideration.  For me, I'm satisfied with what I'm seeing.

--72-- Mike --  W0MNE

Glenn
 

focus a bit poor for a closeup but this is internals of build 1, uBITX relay. "Virtual" branded.





On Tue, Oct 9, 2018 at 03:43 PM, Dr. Flywheel wrote:
Regarding the relay spec differences, can anyone open the case of the "good" and the "bad" and take photos of the innards? It would be instructive to all of us to understand how to choose relays for future applications.
 
--Ron    N7FTZ

On Mon, Oct 8, 2018 at 9:38 PM Mike Doty via Groups.Io <mikedoty=reagan.com@groups.io> wrote:
Good evening Kees,
As I said in an earlier post, with the Axicom relays installed in 3 different rigs, I am not seeing any harmonic greater than -50dBm on any band from 80 thru 10 mtrs.  I have fuzzy pictures of the SA results for each band but I didn't want to take up server space posting them here.  I can make them available to anyone that wants them but the files are large.

Looking at the 3 rigs I have I found two different brands of relays installed, Hongfa and Virtual.  Readingt the datasheets for both brands and the Axicom relays the only difference I can see in the specs presented is a difference in coil resistance.  Notably though, neither datasheet for the installed brands gives a spec for RF isolation which makes me wonder whether they are actually rated for RF usage.  The datasheet for the Axicom indicates -39dB at 100 MHz.  I can't think of any other explanation for the results I'm getting but, as I also said in an earlier post, these are MY results that I have passed along for consideration.  For me, I'm satisfied with what I'm seeing.

--72-- Mike --  W0MNE

 

Great Mike,

Just what we need! great find!

Raj

At 09-10-18, you wrote:
Thanks Jack. I wish I could say that I discovered this intentionally but, to be honest, it was completely accidental. I had removed the original relays from my first uBiTX while looking for a solution to the harmonics issue. In doing so, I broke a pin on one of the original relays. I had some of the Axicom relays in the junk box so I ended up sticking those in as replacements for all 5 of the relays. When I put things back together and looked at the output I saw that the harmonics were all down below -50dB. I still had 4 of the Axicom relays left in the junk box so I replaced the 4 relays on my second Ver 3 rig, leaving K1 in place. I saw the same results. To be sure that there wasn't something else involved before posting to the group, I ordered more relays and replaced the same 4 relays in my Ver 4 uBiTX. Again, the same results. I've attached pictures of the spectrum analyzer results for both of my Ver 3 rigs so you can see that it wasn't just coincidental. Unfortuna
tely I didn't take pictures of the other two rigs before replacing the relays but they both originally had harmonics around -35dB before the relay swaps. All of the spectrum analyzer results for each rig shown are on 40 meters at 10 watts with the SA span from 1 MHz to 100MHz but I cannot see any harmonics above -50dB on any band, 80 - 10.
--73-- Mike

Nick VK4PP
 

I suppose we are learning the difference between a $5 relay and a $1 relay....

I see the Omron G6 I plan on using with my LPF boards has a 45db isolation at 50mhz!

73 Nick VK4PP.

 

Nick,

I tried the mod with a set of Omron and the harmonics were the same about -36 db

I tried with Panosonic relays, slightly smaller and the harmonic were TERRIBLE at -12db

Not price but internal construction I guess is important!

The SA was at 10K BW and 3K VBW and set for 3-53MHz frequency. I recommend this
to Mike to check properly.

Raj

At 09-10-18, you wrote:
I suppose we are learning the difference between a $5 relay and a $1 relay....

I see the Omron G6 I plan on using with my LPF boards has a 45db isolation at 50mhz!

73 Nick VK4PP.

iz oos
 

Would be interesting for me knowing whether these relays make such a significant improvement to the version 3 as well.


Il 09/ott/2018 08:57, "Raj vu2zap" <rajendrakumargg@...> ha scritto:
Nick,

I tried the mod with a set of Omron and the harmonics were the same about -36 db

I tried with Panosonic relays, slightly smaller and the harmonic were TERRIBLE at -12db

Not price but internal construction I guess is important!

The SA was at 10K BW and 3K VBW and set for 3-53MHz frequency. I recommend this
to Mike to check properly.

Raj

At 09-10-18, you wrote:
>I suppose we are learning the difference between a $5 relay and a $1 relay....
>
>I see the Omron G6 I plan on using with my LPF boards has a 45db isolation at 50mhz!
>
>73 Nick VK4PP.





Clark Martin
 

Per the Axicom and Virtual spec sheets, the Axicom draws about 20% more power.  That could mean a larger gap and thus lower contact to contact capacitance.

Clark Martin
KK6ISP

On Oct 8, 2018, at 9:38 PM, Mike Doty via Groups.Io <mikedoty@...> wrote:

Looking at the 3 rigs I have I found two different brands of relays installed, Hongfa and Virtual.  Readingt the datasheets for both brands and the Axicom relays the only difference I can see in the specs presented is a difference in coil resistance.  Notably though, neither datasheet for the installed brands gives a spec for RF isolation which makes me wonder whether they are actually rated for RF usage.  The datasheet for the Axicom indicates -39dB at 100 MHz.  I can't think of any other explanation for the results I'm getting but, as I also said in an earlier post, these are MY results that I have passed along for consideration.  For me, I'm satisfied with what I'm seeing.

iz oos
 

Can these good relays be bought through ebay? If so could you provide a link to a ebay vendor of the exact type you have?


Il 09/ott/2018 16:19, "Clark Martin" <kk6isp@...> ha scritto:
Per the Axicom and Virtual spec sheets, the Axicom draws about 20% more power.  That could mean a larger gap and thus lower contact to contact capacitance.

Clark Martin
KK6ISP

On Oct 8, 2018, at 9:38 PM, Mike Doty via Groups.Io <mikedoty@...> wrote:

Looking at the 3 rigs I have I found two different brands of relays installed, Hongfa and Virtual.  Readingt the datasheets for both brands and the Axicom relays the only difference I can see in the specs presented is a difference in coil resistance.  Notably though, neither datasheet for the installed brands gives a spec for RF isolation which makes me wonder whether they are actually rated for RF usage.  The datasheet for the Axicom indicates -39dB at 100 MHz.  I can't think of any other explanation for the results I'm getting but, as I also said in an earlier post, these are MY results that I have passed along for consideration.  For me, I'm satisfied with what I'm seeing.