Topics

Harmonics and Relay Replacement

Ripley
 

Here are snapshots for 20 and 10 meters after the relays were replaced with the Axicom components. Sorry, I didn’t capture the harmonics profile at 14.2 and 28.8 Mhz before the relay change but there nothing exceeding the -43 dB threshold for FCC compliance. Once again Yellow = SSB and magenta is CW

 

 

Picture 1 is of harmonics and spurs on 28.8 Mhz

Picture 2 is the harmonic profile at 14.2 Mhz

 

A couple of other notes: using a 12 volt 50 watt power supply my power out is 10 watts on 80, 40, and 20 meters, dropping down to 8 watts on 15 meters and 6 watts at 10 meters.

 

Ripley

 

 

Sent from Mail for Windows 10

 

From: Ripley
Sent: Sunday, October 14, 2018 7:52 PM
To: BITX20@groups.io
Subject: RE: [BITX20] Harmonics and Relay Replacement

 

Hello All,

 

I installed the Axicom relays in my uBITX (ver 4) test bed this afternoon and ran tests 3.8, 7.2, and 14.2 Mhz. Here are the before and after snapshots. Yellow is SSB and magenta CW.

 

Pic #1 is 7.2 MHz before relay change

Pic #2; 7.2 Mhz after relay change. Note that the CW third order harmonic was brought down by about 7 dBs but still exceeds the -43 dBs threshold for FCC compliance

Pic #3; 3.8Mhz before relay change

Pic #4; 3.8 Mhz after relay change

 

The biggest drops were in SSB mode as others have pointed out already.

 

So you know the base line of my build. The 45 Mhz crystal for spur reduction has been installed but only the crystal itself. Driver transistors Q92, Q93, Q96, Q97 were replaced with metal can 2N2222A and the emitter resistor changed to 11 ohms. AGC was added along with a manual RF gain control.

 

Ripley

KD8UYQ

 

 

Sent from Mail for Windows 10

 

From: Joe Puma
Sent: Sunday, October 14, 2018 5:57 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics and Relay Replacement

 

Yea but changing the relays looks like the real winner here. 

 

 

Joe

 

 


On Oct 14, 2018, at 5:31 PM, iz oos <and2oosiz2@...> wrote:

Looking at pic #2 seems to me that adding a 47nF capacitor to ground at each coil terminal as Arv hypothesized would make the uBitx a leap close to be legal compliant with respect to the harmonics.

Il 14/ott/2018 20:31, "Kees T" <windy10605@...> ha scritto:
>
> Plots of the coupling between N/C contacts on either side of the relay (which will include the armature) and what they look like with the addition of a 47nF capacitor to ground at each coil terminal.  You can see the dB of isolation improvement.
>
> #1 HK16F-SHG "16 pin" relay (like the original uBITX relays)
> #2  same as #1 but with the 2 capacitors added (see less coupling ....a good thing).
> #3 NAIS TQ2-H "10 pin" smaller relay which does not have the long armature
> #4 same as #3 but with the 2 capacitors added (less coupling .....a good thing)
> #5 Axicom .....TBD waiting for the relays.
> #6 same as #5 but with the 2 capacitors added (less coupling .....a good thing)
>
> 73 Kees K5BCQ
>
>
>
>

 

 

iz oos
 

Would be there at significant advantage to replace all the 5 relays, or is enough to replace only the three at the PA LPFs?


Il 15/ott/2018 02:20, "Ripley" <bob.ripley@...> ha scritto:

Here are snapshots for 20 and 10 meters after the relays were replaced with the Axicom components. Sorry, I didn’t capture the harmonics profile at 14.2 and 28.8 Mhz before the relay change but there nothing exceeding the -43 dB threshold for FCC compliance. Once again Yellow = SSB and magenta is CW

 

 

Picture 1 is of harmonics and spurs on 28.8 Mhz

Picture 2 is the harmonic profile at 14.2 Mhz

 

A couple of other notes: using a 12 volt 50 watt power supply my power out is 10 watts on 80, 40, and 20 meters, dropping down to 8 watts on 15 meters and 6 watts at 10 meters.

 

Ripley

 

 

Sent from Mail for Windows 10

 

From: Ripley
Sent: Sunday, October 14, 2018 7:52 PM
To: BITX20@groups.io
Subject: RE: [BITX20] Harmonics and Relay Replacement

 

Hello All,

 

I installed the Axicom relays in my uBITX (ver 4) test bed this afternoon and ran tests 3.8, 7.2, and 14.2 Mhz. Here are the before and after snapshots. Yellow is SSB and magenta CW.

 

Pic #1 is 7.2 MHz before relay change

Pic #2; 7.2 Mhz after relay change. Note that the CW third order harmonic was brought down by about 7 dBs but still exceeds the -43 dBs threshold for FCC compliance

Pic #3; 3.8Mhz before relay change

Pic #4; 3.8 Mhz after relay change

 

The biggest drops were in SSB mode as others have pointed out already.

 

So you know the base line of my build. The 45 Mhz crystal for spur reduction has been installed but only the crystal itself. Driver transistors Q92, Q93, Q96, Q97 were replaced with metal can 2N2222A and the emitter resistor changed to 11 ohms. AGC was added along with a manual RF gain control.

 

Ripley

KD8UYQ

 

 

Sent from Mail for Windows 10

 

From: Joe Puma
Sent: Sunday, October 14, 2018 5:57 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics and Relay Replacement

 

Yea but changing the relays looks like the real winner here. 

 

 

Joe

 

 


On Oct 14, 2018, at 5:31 PM, iz oos <and2oosiz2@...> wrote:

Looking at pic #2 seems to me that adding a 47nF capacitor to ground at each coil terminal as Arv hypothesized would make the uBitx a leap close to be legal compliant with respect to the harmonics.

Il 14/ott/2018 20:31, "Kees T" <windy10605@...> ha scritto:
>
> Plots of the coupling between N/C contacts on either side of the relay (which will include the armature) and what they look like with the addition of a 47nF capacitor to ground at each coil terminal.  You can see the dB of isolation improvement.
>
> #1 HK16F-SHG "16 pin" relay (like the original uBITX relays)
> #2  same as #1 but with the 2 capacitors added (see less coupling ....a good thing).
> #3 NAIS TQ2-H "10 pin" smaller relay which does not have the long armature
> #4 same as #3 but with the 2 capacitors added (less coupling .....a good thing)
> #5 Axicom .....TBD waiting for the relays.
> #6 same as #5 but with the 2 capacitors added (less coupling .....a good thing)
>
> 73 Kees K5BCQ
>
>
>
>

 

 

Matthias Zwoch
 

Am 14.10.2018 um 23:57 schrieb Joe Puma:
Yea but changing the relays looks like the real winner here.
Hello Joe,

It is not a big problem to get the HFD27 desoldered. A good desolder litz (I used 2,5mm from Felder) and a bit judding and pulling an they will come out without any damages at the PCB and the relais. Desoldered all 5. They will go in the scrapbox and this evenig the AXICOMs will take their places.

73, Matthias DD7NT

Nigel G4ZAL
 

With reference to the article, where the AXICOM type D2n V23105-A5476-A201 is described as the best relay
http://www.i1wqrlinkradio.com/antype/ch97/chiave50.htm

I have located some of these in the UK as they are British Telecom specified relays with coil resistance of 280 ohms and power consumption of 515mW and operating current of 27mA
I paid  just under 1GBP each, (US$1.30) delivered.
Relay spec (scroll down to find the BT spec)
https://www.qsl.net/on7eq/pdf/axicom_dil_hf_relays.pdf

I have no means of testing the harmonic difference before and after installation, but hope they will not upset anything with the extra power demand?

Nigel - G4ZAL

a.vision
 


Hi Nigel do you have a link for your UK supplier Thanks Graham


Sent from my Samsung Galaxy smartphone.

-------- Original message --------
From: Nigel G4ZAL <nigel@...>
Date: 15/10/2018 12:45 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics and Relay Replacement

With reference to the article, where the AXICOM type D2n V23105-A5476-A201 is described as the best relay
http://www.i1wqrlinkradio.com/antype/ch97/chiave50.htm

I have located some of these in the UK as they are British Telecom specified relays with coil resistance of 280 ohms and power consumption of 515mW and operating current of 27mA
I paid  just under 1GBP each, (US$1.30) delivered.
Relay spec (scroll down to find the BT spec)
https://www.qsl.net/on7eq/pdf/axicom_dil_hf_relays.pdf

I have no means of testing the harmonic difference before and after installation, but hope they will not upset anything with the extra power demand?

Nigel - G4ZAL

Nigel G4ZAL
 

This seller on ebay UK is selling packs of 2 or 4 - I grabbed some 4's ;-)

https://www.ebay.co.uk/itm/331766915816

Nigel

MVS Sarma
 

Even RS componenets have them
 I had ordered on in.rsdelivers.com


On Mon, Oct 15, 2018 at 9:33 PM Nigel G4ZAL <nigel@...> wrote:
This seller on ebay UK is selling packs of 2 or 4 - I grabbed some 4's ;-)

https://www.ebay.co.uk/itm/331766915816

Nigel

a.vision
 

Thanks Nigel appreciated



Sent from my Samsung Galaxy smartphone.

-------- Original message --------
From: Nigel G4ZAL <nigel@...>
Date: 15/10/2018 17:03 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics and Relay Replacement

This seller on ebay UK is selling packs of 2 or 4 - I grabbed some 4's ;-)

https://www.ebay.co.uk/itm/331766915816

Nigel

Matthias Zwoch
 

Mounted the AXICOM V23105-A5303-A201 this evening. Replaced all HFD27. And bingo - the harmonics on 3,5 / 7 /10.5 meet the german RegTP requirements (-40 dB). Would also meet the -43 FCC limit. For the higher bands I will test later. Need the HP boatanchors at our local club for that. Bought the relais from the ebay seller "breconjess" UK.
So the first problem is solved. Next are the spur fixes, then AGC...

73 Matthias, DD7NT

Joe Puma
 

I plan on doing the same. I already safely removed the 8 pin Op amp very clean too. So I shouldn’t have any issue with the relays, hopefully. Waiting to order mine.


Joe

On Oct 15, 2018, at 4:24 AM, Matthias Zwoch <zwoch@...> wrote:

Am 14.10.2018 um 23:57 schrieb Joe Puma:
Yea but changing the relays looks like the real winner here.
Hello Joe,

It is not a big problem to get the HFD27 desoldered. A good desolder litz (I used 2,5mm from Felder) and a bit judding and pulling an they will come out without any damages at the PCB and the relais. Desoldered all 5. They will go in the scrapbox and this evenig the AXICOMs will take their places.

73, Matthias DD7NT



Lawrence Galea
 

How easy is it to try to shield the coil and earth the shield?
Regards
Lawrence

On Tue, Oct 16, 2018 at 9:38 PM Kees T <windy10605@...> wrote:
Received the AXICOM V23105-A5303-A201 relays from mouser this morning and tested them. The results were NOT as expected (not low enough). Dissected one to make sure it had the AXICOM internal structure .....it does.

What would you consider the proper way of testing the relay for coupling ? I connected the two relay N/C contacts (which are also connected to the relay armature) ....one side to the TG and one side to the SA with/without a 50 ohm resistor across the TG output at the relay. Also attached a small wire from Ground to Ground. Then I added 47nF caps to ground at the coil leads to see the effect. The AXICOM relay had a 4dB reduction, the uBITX relay had a 9dB reduction indicating to me more had signal coupled to that coil.

73 Kees K5BCQ

Kees T
 

It's very difficult (impossible) to do anything inside the relay. Those 47nF capacitors from both ends of the coil to the nearest ground definitely help reduce the coupling with ALL the relays tried so far. I believe Arv suggested doing that.

I'm at a loss for the proper way to test coupling through the relay from one side to the other and/or through the N/O contact.

The AXICOM spec says the RF isolation at 100MHz is -39dB.

73 Kees K5BCQ

MVS Sarma
 

I suppose that the prescribed relay was 23105 5403 A201. i see that your relay has 5303 instead.
was it a typo?
regards
sarma vu3zmv



On Wed, 17 Oct 2018 03:22 Kees T, <windy10605@...> wrote:
It's very difficult (impossible) to do anything inside the relay. Those 47nF capacitors from both ends of the coil to the nearest ground definitely help reduce the coupling with ALL the relays tried so far. I believe Arv suggested doing that.

I'm at a loss for the proper way to test coupling through the relay from one side to the other and/or through the N/O contact.

The AXICOM spec says the RF isolation at 100MHz is -39dB.

73 Kees K5BCQ

Kees T
 

Received the AXICOM V23105-A5403-A201 relays from mouser this morning and tested them. The results were NOT as expected (not low enough). Dissected one to make sure it had the AXICOM internal structure .....it does.

What would you consider the proper way of testing the relay for coupling ? I connected the two relay N/C contacts (which are also connected to the relay armature) ....one side to the TG and one side to the SA with/without a 50 ohm resistor across the TG output at the relay. Also attached a small wire from Ground to Ground. Then I added 47nF caps to ground at the coil leads to see the effect. The AXICOM relay had a 4dB reduction, the uBITX relay had a 9dB reduction indicating to me more had signal coupled to that coil. 

73 Kees K5BCQ

Kees T
 

You may have seen all the discussion on using AXICOM relays. Until that is flattened and I understand the "why" I am refunding your money for the K5BCQ LPF board kits which were ordered as I continue to investigate further.

Attached is a picture of the AXICOM V23105-A5403-A201 relays just received from Mouser. You can see that there are some physical differences between them and the previous AXICOM relay pictures posted (coil spacing to contacts, and ?). 

A good friend of mine, Glen, has donated an unmodified uBITX board for my future testing. Thank you Glen.

 
73 Kees K5BCQ

Arv Evans
 

Kees

Some possible areas to look into:
  • Are there resonances in the relay activation path when (activated, or inactive)?
    Thinking about permeability change in relay coils when current is flowing?

  • What is the self-resonant frequency of the relay coils when activated and when
    inactive?

  • Is there any RF on the relay coils during transmit mode (RF Detector or O-scope)?
    Seems there should be none...?

  • How much RF, and at what frequency, is there on the toroids, other than the ones
    that have been activated for a particular band?

  • What happens to the harmonics and spurs when all but the active filter is removed
    from the PCB?

  • L-31 is very close to an RF PA heat sink.  Is it picking up unwanted RF?  Is it picking
    up "unbalanced RF" because it is coupling to only one side of the RF PA output?

  • Is imbalance between RF PA MOSFETs causing harmonic or spurious output?

  • If input to the RF PA is clean, is it still clean if the RF PA output is terminated in a
    purely resistive dummy load (without any LPFs connected)?

  • If an LPF is connected by short jumpers instead of via the relay, is output clean
    or unclean?  Is it clean if the relay activation lead is at ground instead of active?

  • There are some who are building their own modular and non-modular versions
    of the uBITX.  I wonder how they are doing with respect to harmonics and spurs?
Looking back over some of the suggested improvements it seems that there may have
been some eureka moments that might have been published before they were well
thought out.  Some of Allison's posts might indicate that we have been focusing on and
treating the symptoms instead of the source problem. 

It is probably unfair that I comment when I do not have the test equipment, skills, or
available time to perform in-depth tests.  But given the situation, talk is about all I
can do.      8-(  

Arv
_._


On Wed, Oct 17, 2018 at 1:38 PM Kees T <windy10605@...> wrote:
You may have seen all the discussion on using AXICOM relays. Until that is flattened and I understand the "why" I am refunding your money for the K5BCQ LPF board kits which were ordered as I continue to investigate further.

Attached is a picture of the AXICOM V23105-A5403-A201 relays just received from Mouser. You can see that there are some physical differences between them and the previous AXICOM relay pictures posted (coil spacing to contacts, and ?). 

A good friend of mine, Glen, has donated an unmodified uBITX board for my future testing. Thank you Glen.

 
73 Kees K5BCQ

F1BFU - Fr - 79
 

Hello Kees, Arv

I am attentive to your discussions on relays. I am not a professional technician so I will definitely ask a silly question. But too bad I start.

Could the relays be replaced by other components (PIN diode, transistor, etc.)?
Can current relays be replaced by AXICOM MT2 relays?

Again, my apologies for disturbing your conversations with naive questions.

73 QRO
Gilles - F1BFU /FR

Le mer. 17 oct. 2018 à 22:27, Arv Evans <arvid.evans@...> a écrit :
Kees

Some possible areas to look into:
  • Are there resonances in the relay activation path when (activated, or inactive)?
    Thinking about permeability change in relay coils when current is flowing?

  • What is the self-resonant frequency of the relay coils when activated and when
    inactive?

  • Is there any RF on the relay coils during transmit mode (RF Detector or O-scope)?
    Seems there should be none...?

  • How much RF, and at what frequency, is there on the toroids, other than the ones
    that have been activated for a particular band?

  • What happens to the harmonics and spurs when all but the active filter is removed
    from the PCB?

  • L-31 is very close to an RF PA heat sink.  Is it picking up unwanted RF?  Is it picking
    up "unbalanced RF" because it is coupling to only one side of the RF PA output?

  • Is imbalance between RF PA MOSFETs causing harmonic or spurious output?

  • If input to the RF PA is clean, is it still clean if the RF PA output is terminated in a
    purely resistive dummy load (without any LPFs connected)?

  • If an LPF is connected by short jumpers instead of via the relay, is output clean
    or unclean?  Is it clean if the relay activation lead is at ground instead of active?

  • There are some who are building their own modular and non-modular versions
    of the uBITX.  I wonder how they are doing with respect to harmonics and spurs?
Looking back over some of the suggested improvements it seems that there may have
been some eureka moments that might have been published before they were well
thought out.  Some of Allison's posts might indicate that we have been focusing on and
treating the symptoms instead of the source problem. 

It is probably unfair that I comment when I do not have the test equipment, skills, or
available time to perform in-depth tests.  But given the situation, talk is about all I
can do.      8-(  

Arv
_._


On Wed, Oct 17, 2018 at 1:38 PM Kees T <windy10605@...> wrote:
You may have seen all the discussion on using AXICOM relays. Until that is flattened and I understand the "why" I am refunding your money for the K5BCQ LPF board kits which were ordered as I continue to investigate further.

Attached is a picture of the AXICOM V23105-A5403-A201 relays just received from Mouser. You can see that there are some physical differences between them and the previous AXICOM relay pictures posted (coil spacing to contacts, and ?). 

A good friend of mine, Glen, has donated an unmodified uBITX board for my future testing. Thank you Glen.

 
73 Kees K5BCQ



--
Gilles - F1BFU/FR

Kees T
 

Gilles, the only naive questions are the ones not asked .....or something like that ;o)

Arv, we (AQRP Wed lunch guys) were speculating that the Constant K filter design used on the uBITX was suspect in that it has terrible out of band matching and the resultant reflections due to poor VSWR might be the cause of the problem .....and that the AXICOM relays "happen to correct" some of that problem. One of the guys checked the Smith Chart results using the original uBITX relays against the AXICOM relays I had purchased for a given uBITX filter design. To his (and my) surprise they are nearly identical. Now, this is using a separate single LPF test fixture board with relays.

We're trying to find an industry standard test fixture for testing relay RF isolation.

73 Kees K5BCQ

Arv Evans
 

Giles

I'm not sure yet that the relays are the source of the problem.  They are probably contributors,
but there may be other culprits as well.  I noted your earlier suggestion that we might try
solid-state switching.  That is a valid approach if the relays are proven to be a major source
of problems.  Problem with solid-state switching for RF is that it is a bit complicated if the
RF voltages exceed reverse-bias on the switching elements.  Now I am wondering if the idle
lines to inactive DC relays could or should be grounded with MOSFET switches?  This might
be more effective than just bypassing the relay operating lines for RF.

As Allison has said, part of the problem is overall board layout.  In trying to keep it compact
some decisions may have been made that compromise the situation regarding spurs and
harmonics. 

Arv
_._


On Wed, Oct 17, 2018 at 3:06 PM F1BFU - Fr - 79 <gilles.f1bfu@...> wrote:
Hello Kees, Arv

I am attentive to your discussions on relays. I am not a professional technician so I will definitely ask a silly question. But too bad I start.

Could the relays be replaced by other components (PIN diode, transistor, etc.)?
Can current relays be replaced by AXICOM MT2 relays?

Again, my apologies for disturbing your conversations with naive questions.

73 QRO
Gilles - F1BFU /FR

Le mer. 17 oct. 2018 à 22:27, Arv Evans <arvid.evans@...> a écrit :
Kees

Some possible areas to look into:
  • Are there resonances in the relay activation path when (activated, or inactive)?
    Thinking about permeability change in relay coils when current is flowing?

  • What is the self-resonant frequency of the relay coils when activated and when
    inactive?

  • Is there any RF on the relay coils during transmit mode (RF Detector or O-scope)?
    Seems there should be none...?

  • How much RF, and at what frequency, is there on the toroids, other than the ones
    that have been activated for a particular band?

  • What happens to the harmonics and spurs when all but the active filter is removed
    from the PCB?

  • L-31 is very close to an RF PA heat sink.  Is it picking up unwanted RF?  Is it picking
    up "unbalanced RF" because it is coupling to only one side of the RF PA output?

  • Is imbalance between RF PA MOSFETs causing harmonic or spurious output?

  • If input to the RF PA is clean, is it still clean if the RF PA output is terminated in a
    purely resistive dummy load (without any LPFs connected)?

  • If an LPF is connected by short jumpers instead of via the relay, is output clean
    or unclean?  Is it clean if the relay activation lead is at ground instead of active?

  • There are some who are building their own modular and non-modular versions
    of the uBITX.  I wonder how they are doing with respect to harmonics and spurs?
Looking back over some of the suggested improvements it seems that there may have
been some eureka moments that might have been published before they were well
thought out.  Some of Allison's posts might indicate that we have been focusing on and
treating the symptoms instead of the source problem. 

It is probably unfair that I comment when I do not have the test equipment, skills, or
available time to perform in-depth tests.  But given the situation, talk is about all I
can do.      8-(  

Arv
_._


On Wed, Oct 17, 2018 at 1:38 PM Kees T <windy10605@...> wrote:
You may have seen all the discussion on using AXICOM relays. Until that is flattened and I understand the "why" I am refunding your money for the K5BCQ LPF board kits which were ordered as I continue to investigate further.

Attached is a picture of the AXICOM V23105-A5403-A201 relays just received from Mouser. You can see that there are some physical differences between them and the previous AXICOM relay pictures posted (coil spacing to contacts, and ?). 

A good friend of mine, Glen, has donated an unmodified uBITX board for my future testing. Thank you Glen.

 
73 Kees K5BCQ


--
Gilles - F1BFU/FR

Gary Anderson
 

I have noticed different capacitance datasheet 'specs' for the AXICOM White D2n and the Black D2n*, although the same part number.
The RF characteristics are the same.

Capacitance                                                 D2n (white)                         D2n* (black)

between coil and contacts                            max. 2 pF                           max. 4pF (between contact and coil)

between adjacent contact sets                     max. 1.5 pF                        max. 2pF (between adjacent contacts)

between open contacts                                max. 1 pF                           max. 2pF

RF Characteristics

Isolation at 100 / 900 MHz                          -39.0 dB / -20.7 dB              same

Insertion loss at 100 / 900 MHz                  -0.02 dB / -0.27 dB              same

V.S.W.R. at 100 / 900 MHz                          1.04 / 1.40                          same

Gilles, the MT2 relays spec less Isolation (- 31.8 dB / - 14.2 dB), I assume this is still true at  HF frequencies too.

Rgds,
Gary
AG5TX