Topics

Wanted Tohtsu CX600NC relay


Richard GD8EXI
 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP


Colin Ranson
 

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Richard GD8EXI
Sent: 08 September 2020 23:05
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP

 


Ian White
 

By having the common port pointing the opposite way from the other two, the CX520D saves a lot of space inside a preamp box. I wish there was a wider choice of relays with that connector layout, and at a similar price point (which rules out the big, expensive EME relays) but I have never found even one alternative.

However, the problems with poor isolation and poor power handling are surprising. I used the same CX520D in the 70cm EME preamp for many years, handling 1kW CW and connected directly to the GaAsFET preamp, all with no damage. So does the performance really fall over a cliff between 432MHz and 1296MHz?

A possible explanation for poor isolation is that there have been at least two versions of that relay, sold under the same model number. In the modern ones, the isolated contacts are grounded onto gold-plated contacts that are screwed into the body. The older ones relied on grounding onto the body itself, which is a poorer contact and also less reliable... bearing in mind that the relay will be operated tens or hundreds of thousands of times, but preamp only has to be unlucky once.

Yet another thought is about the settings of the moving arms and the actuator plungers. These settings are quite critical to achieve the correct contact pressures, and the TohTsu relays aren't exactly built like Swiss watches.

As I said, I do wish there were other relays with that highly practical port layout and at a similar price point.

73 from Ian GM3SEK



On 09/09/2020 13:29, Colin Ranson wrote:

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Richard GD8EXI
Sent: 08 September 2020 23:05
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP

 


ian hope (2E0IJH)
 

I always use preamps that have internal bypass relays, even if they are only on the RX line and drop the power to those before switching the mast head relay, we use either cx520's or Cx600's depending on application, But as Ian says the older versions of both the cx600 and the cx520 had a different design.
 
Ian
M5IJH

 
 
Sent: Wednesday, September 09, 2020 at 2:47 PM
From: "Ian White" <gm3sek@...>
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

By having the common port pointing the opposite way from the other two, the CX520D saves a lot of space inside a preamp box. I wish there was a wider choice of relays with that connector layout, and at a similar price point (which rules out the big, expensive EME relays) but I have never found even one alternative.

However, the problems with poor isolation and poor power handling are surprising. I used the same CX520D in the 70cm EME preamp for many years, handling 1kW CW and connected directly to the GaAsFET preamp, all with no damage. So does the performance really fall over a cliff between 432MHz and 1296MHz?

A possible explanation for poor isolation is that there have been at least two versions of that relay, sold under the same model number. In the modern ones, the isolated contacts are grounded onto gold-plated contacts that are screwed into the body. The older ones relied on grounding onto the body itself, which is a poorer contact and also less reliable... bearing in mind that the relay will be operated tens or hundreds of thousands of times, but preamp only has to be unlucky once.

Yet another thought is about the settings of the moving arms and the actuator plungers. These settings are quite critical to achieve the correct contact pressures, and the TohTsu relays aren't exactly built like Swiss watches.

As I said, I do wish there were other relays with that highly practical port layout and at a similar price point.

73 from Ian GM3SEK

 

 

On 09/09/2020 13:29, Colin Ranson wrote:

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Richard GD8EXI
Sent: 08 September 2020 23:05
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP

 


Colin Ranson
 

Same here no matter what I always, under advice from G3XDY/G4DDK and the VHF/UHF DX book, use an isolating relay...... however the tiny SMD relay in my HA8ET 70cm pre-amp has so far enabled the device to  survive, used last night in the 70cm  UKAC with 250w.

 

73’s

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: ian hope (2E0IJH)
Sent: 09 September 2020 15:07
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

I always use preamps that have internal bypass relays, even if they are only on the RX line and drop the power to those before switching the mast head relay, we use either cx520's or Cx600's depending on application, But as Ian says the older versions of both the cx600 and the cx520 had a different design.

 

Ian

M5IJH

 

 

Sent: Wednesday, September 09, 2020 at 2:47 PM
From: "Ian White" <gm3sek@...>
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

By having the common port pointing the opposite way from the other two, the CX520D saves a lot of space inside a preamp box. I wish there was a wider choice of relays with that connector layout, and at a similar price point (which rules out the big, expensive EME relays) but I have never found even one alternative.

However, the problems with poor isolation and poor power handling are surprising. I used the same CX520D in the 70cm EME preamp for many years, handling 1kW CW and connected directly to the GaAsFET preamp, all with no damage. So does the performance really fall over a cliff between 432MHz and 1296MHz?

A possible explanation for poor isolation is that there have been at least two versions of that relay, sold under the same model number. In the modern ones, the isolated contacts are grounded onto gold-plated contacts that are screwed into the body. The older ones relied on grounding onto the body itself, which is a poorer contact and also less reliable... bearing in mind that the relay will be operated tens or hundreds of thousands of times, but preamp only has to be unlucky once.

Yet another thought is about the settings of the moving arms and the actuator plungers. These settings are quite critical to achieve the correct contact pressures, and the TohTsu relays aren't exactly built like Swiss watches.

As I said, I do wish there were other relays with that highly practical port layout and at a similar price point.

73 from Ian GM3SEK

 

 

On 09/09/2020 13:29, Colin Ranson wrote:

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Richard GD8EXI
Sent: 08 September 2020 23:05
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP

 

 


alwyn.seeds1
 

Dear Richard,

I agree. The CX3500 gives very good isolation.

Power handling, however, is limited- looking at the data sheets, power rating has been reduced significantly over the years, particularly at high frequencies.

The EME-ers seem to have burned up quite a few.

My favourites are the Radiall Ramses series, quite frequently available new surplus and able to manage the full N-Type rating at UHF and above.

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


DF6NA Rainer
 

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Richard GD8EXI
Sent: 08 September 2020 23:05
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 

Andy
    I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.

A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.

Richard
GD8EXI


On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:

Hi, I need a Tohtsu CX600NC 12v DC relay.

Before I buy new from a store does anyone have a spare they'd like to sell?

Thanks Andy GD1MIP

 



alwyn.seeds1
 

Dear All,

With the Amphenol relays, some models have good isolation; some not.

I burned out a stepped attenuator on 2m due to leakage on one of the types that look like the 316-10744-3, but with BNC connectors.

Regards,

Alwyn
_____________________________________________________

Alwyn Seeds, Director
114 Beaufort Street (Management) Company Ltd.,
114 Beaufort Street,
London,
SW3 6BU

114 Beaufort Street (Management) Company Ltd., Registered in England and Wales: No. 02797775 Registered Office Address: 114 Beaufort Street, London, SW3 6BU
______________________________________________________


Richard GD8EXI
 


After reading the comment re different versions of CX600N relays I thought I better retest mine, which is about 30 years old and silver-plated inside and out.
 
Isolation
53dB at 30MHz
49dB at 50MHz
39dB at 144MHz
30dB at 432MHz
21dB at 1296MHz
Measured as per the Tohtsu spec sheet with a 50ohm load on the com port.

These figures are ~ 9dB worse than the current manufactures specs adding weight to the idea there are two versions. The nearly flat contacts on mine are only 1.4mm apart and 5.7mm in diameter so a calculated capacitance of 0.65pf so the poor isolation is no surprise.
 
The danger level for some preamps is about 0dBm, 1mW so there is not adequate isolation on VHF, even for a 10 watt Tx without a second isolation relay!
No surprise I destroyed a few GASFETs on 432 MHz!
 
I also tested the isolation of two CZX3500, one dated, 2016, the other brought in about 2009, date now rubbed off.
 
Both >85dB at 432MHz and >80dB at 1296MHz .
 
So plenty of isolation even for a QRO station on 1296MHz
 
The trouble with a second isolation relay is that it will increase your path loss on RX, which could be critical on 432MHz and above for EME and even extreme terrestrial. Certainly not needed with a CZX3500, which is a double relay anyway.
 
As to power handling of the CZX3500s, no I have not destruction tested them yet! However I have used them on both 432MHz and 1296MHz for 400 watts SSB and they survived for years. However with 500 watts of CW on 432MHz the CZX3500 runs hot, so as Alwyn stated not suitable for EME with a 100% duty cycle.
 
 
Richard
GD8EXI


On 09/09/2020, 14:47, "Ian White" <gm3sek@...> wrote:

  

By having the common port pointing the opposite way from the other two, the CX520D saves a lot of space inside a preamp box. I wish there was a wider choice of relays with that connector layout, and at a similar price point (which rules out the big, expensive EME relays) but I have never found even one alternative.
 


However, the problems with poor isolation and poor power handling are surprising. I used the same CX520D in the 70cm EME preamp for many years, handling 1kW CW and connected directly to the GaAsFET preamp, all with no damage. So does the performance really fall over a cliff between 432MHz and 1296MHz?
 


A possible explanation for poor isolation is that there have been at least two versions of that relay, sold under the same model number. In the modern ones, the isolated contacts are grounded onto gold-plated contacts that are screwed into the body. The older ones relied on grounding onto the body itself, which is a poorer contact and also less reliable... bearing in mind that the relay will be operated tens or hundreds of thousands of times, but preamp only has to be unlucky once.
 
 

Yet another thought is about the settings of the moving arms and the actuator plungers. These settings are quite critical to achieve the correct contact pressures, and the TohTsu relays aren't exactly built like Swiss watches.
 


As I said, I do wish there were other relays with that highly practical port layout and at a similar price point.
 

 

73 from Ian GM3SEK

 
 


 

 
 


 

 
 

On 09/09/2020 13:29, Colin Ranson wrote:

 
    
 

Andy,    I think the CX3500 is a copy of the venerable Amphenol 316-10744 series, of which I was fortunate enough to rescue several from a defunct H.O. RF switching station many years ago.   One was 48v, the rest were 26v except one which was 12v !    These are just as good, if not better than the Tohtsu, in build quality at least.

 

What is rare, and I would love one for an application, is the same build but the common (centre) N connector coming out at 180 degrees so that the common can poke out of a plastic (mast head pre-amp) box for connection to the antenna.   Unfortunately the Tohtsu CX520 just does not cut it as far as isolation or power handling is concerned. I burnt one out with 23cm at 240w even when properly sequenced.

 

Regards Colin de G8LBS.

 

Sent from  Mail <https://go.microsoft.com/fwlink/?LinkId=550986>  for Windows 10

 

 

From: Richard GD8EXI <mailto:perwick@...>
 Sent: 08 September 2020 23:05
 To: UKMicrowaves@groups.io
 Subject: Re: [UKMicrowaves] Wanted Tohtsu CX600NC relay

 
 

Andy
     I have one which was retired from active service many years ago as the isolation was not good enough on 432MHz and above, destroying the preamp device. I might sell it but, what band is it for and how much isolation do you need. I can re measure it but from memory it was less than 40dB of isolation on 432 MHz and above, not enough if you are running 100watts plus.
 
 A CX3500 is much better, if you need good isolation, as it has a double switch and the unused bar is grounded both ends. The isolation is so good it is difficult to measure, being in my experience greater than they 65dB they claim, more like 80dB even on 1296MHz.
 
 Richard
 GD8EXI
 
 
 On 08/09/2020, 21:20, "Andy GD1MIP" <gd1mip@...> wrote:
 

Hi, I need a Tohtsu CX600NC 12v DC relay.
 
 Before I buy new from a store does anyone have a spare they'd like to sell?
 
 Thanks Andy GD1MIP
 

 

 

 
 



Andy GD1MIP
 

Thanks Richard (and all) for the offers.

Firstly  I got my CX numbers messed up. My 300w 70cm amplifier uses a CX140D on input and a CX600NC on the output. The offending / damaged  relay is the CX140D. The contact arm (armature?) has bent slightly meaning it's contacts now sit in the middle of the NO & NC connections and the plastic adjusting screw has deformed (excess heat or cheap material?) See picture here.... https://drive.google.com/folderview?id=1ogQ-6vTKJvIyQ_lvDlGNF_lzGzMqHC6U

So I need a CX140D or a better alternative. I see that a couple of UK companies stock them so should be ok. 

Andy GD1MIP