High Isolation Relays for 23cm

[VK4ZEJ]

Admin edit: Topic split, to keep each thread "on topic"


Hi All

If anyone knows of a source of coaxial relays that will handle up to 100w with very good isolation at 23cm please let us know. I am having trouble getting answers from companies that do supply them.

Eddie

[VK2OMD]

If anyone knows of a source of coaxial relays that will handle up to 100w with very good isolation at 23cm please let us know. I am having trouble getting answers from companies that do supply them.

Datasheets will usually give you attenuation in dB, maximum power in W and isolation in dB, all vs frequency.

If you have somewhat nebulous requirements like "very good isolation", that will make finding a match somewhat challenging, because that is not the languate they speak.

Low end coax relays have "rather low" isolation by the time you reach 1000MHz, so to get "very good" isolation with them, you may need to cascade relays. Better relays that go into the GHz range may satisfy your need for "very good" isolation.

I suggest you look at your tx power, the LNA's power withstand, and come to a quantitative view of minimum isolation for your application.

Owen

[VK3XDK]

In my experience, coaxial relays will handle a lot more power than their data sheets suggest- As long as SWR is correct and you are not "hot switching"
Obviously "tread with care"

[VK2OMD]

In my experience, coaxial relays will handle a lot more power than their data sheets suggest- As long as SWR is correct and you are not "hot switching"
Obviously "tread with care"

If you reverse engineer the loss and power vs freq specs on most coax relays, there emerges a common theme... they may withstand say 5W of loss and as loss in dB goes up with freq, max power becomes less. I think it safer to assume they are not intended for hot switching at maximum power unless the data sheet says otherwise.

The OP's real issue is the meaning of "very good isolation". As you know, a requirement of 60dB is met by more relays than 80dB, and a lot of inexpensive coax relays good for 100W won't go near 80dB isolation at 1300MHz.

If transmit power is 50dBm and say the LNA could safely withstand 15dBm, then one needs a relay with at least 35dB isolation, 35 plus some safety margin and for example, the common Dowkey 60a with 20dB of isolation won't cut the mustard.

Owen

[VK4GHZ]

If anyone knows of a source of coaxial relays that will handle up to 100w with very good isolation at 23cm please let us know. I am having trouble getting answers from companies that do supply them.

Eddie, try: http://vk4ghz.com/transfer-relays/

If cost is a perceived factor against the ACE Technology relays ($90ea), then the same eBay seller mentioned in the article also has other transfer relays (branded "High Gain Telecom") for ~$55 ea.
An isolation test was performed on one of these HGT transfer relays at last Sunday's VK4 microwave test and tune day, and exceeded 80dB, the limit of measurement at the time.
By all accounts, isolation appears to be as good as the ACE Technology transfer relays.

However, the ACE Technology relays on offer from this seller have demonstrated to behave more like a conventional changeover relay.
Fully explained in my article.

[VK2KRR]

I use the CZX-3500 TOHTSU COAXIAL RELAY on 23cm. They will take 400W OK at 23cm. They are rated for 100W at 6 GHz.

http://www.imark.com.au/index.php?conte ... _coaxial_n

http://www.imark.com.au/PDF/PD851461.pdf (Spec Sheet)

CZX 3500 Relay

cr_n_05.jpg (11.09 KiB) Viewed 3186 times

[VK2DVZ]

An even better relay than those mentioned so far is the HF 2000/6. Unfortunately it is no longer produced, but may be available on the second hand market - but I doubt it!

I used mine for many years on 23cm and never turned off the preamp during TX as the relay isolation was sufficient to protect it. The specs suggest >90dB isolation at 23cm and a power handling capability of 400w at 6GHz, all based on a N connector platform.

Due to a change of feed horn the HF 2000/6 is not required for it's extra isolation, but I will not be parting with it as I have a use in mind for my relay - sorry....

See link for details of relay: http://www.ssbusa.com/relays.html

(Yes it was an expensive relay).
Edit-corrected model number of relay.

[ZL2BKC]

If anyone knows of a source of coaxial relays that will handle up to 100w with very good isolation at 23cm please let us know. I am having trouble getting answers from companies that do supply them.

Eddie, try: http://vk4ghz.com/transfer-relays/

If cost is a perceived factor against the ACE Technology relays ($90ea), then the same eBay seller mentioned in the article also has other transfer relays (branded "High Gain Telecom") for ~$55 ea.
An isolation test was performed on one of these HGT transfer relays at last Sunday's VK4 microwave test and tune day, and exceeded 80dB, the limit of measurement at the time.
By all accounts, isolation appears to be as good as the ACE Technology transfer relays.

However, the ACE Technology relays on offer from this seller have demonstrated to behave more like a conventional changeover relay.
Fully explained in my article.

I have since purchased 2 High Gain Telecom relays and have found them to be 100% identical to the ACE Technologies relays refered to in the above thread. I tested them using the same methodology as the ACE and they show an identical 90dB isolation at 1296. Just for laughs I put them on a precission scale and their weight also agreed

Also for the record the cheaper High Gain relays has been used on my W6PQL 150W 23cm amp during the last field day contest and survived all of the abuse I put at it with no damage to the Minikits preamp off the same relay.

On the subject of relays I couldn't resist another bargin. Maybe I might have to start seeking professional help for being a relay addict on eBay after recently purchasing 2 of the following relays at $25 ea. Note there are still 3 more remaining
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0763074353

From the outside they look like a relay but don't to be put off with a narrow frequency spec, it actually has an extra twist. It allows you to energise both contacts simultaneously, and when that happens it implicitly pulls in a matching network which generates a power split between 1.8 and 2.0 GHz. If you just energise one coil then it behaves like a traditional realy, also with good isolation of ~70dB @ 1296 according to my notes.
This may have applications for a antenna combiner/switch...... I'm still trying to come up with some interesting AR applications. Slightly dangerous if the sequencing is not correct or a contact fails as you can achive 0dB isolation between ports which is not a good look if it happens to connect 100W to a RX preamp.

73,
Wayne

[VK4CZ]

Also for the record the cheaper High Gain relays has been used on my W6PQL 150W 23cm amp during the last field day contest and survived all of the abuse I put at it.

Great news Wayne.

After last weeks uWave Test & Tune day we tested the High Gain Telecom relay I currently use on my 70cm LNA and it showed that it had great potential (as Adam decribed above), so I've ordered a few more. I'll now put them to good use on my 150w PE1RKI 23cm amp project as well as LNA projects.

[VK2EM]

You could try these relays, they may be what is needed for 1296MHz ...

http://www.ebay.com.au/itm/291090719893 ... 1423.l2649

[VK2OMD]

You could try these relays, they may be what is needed for 1296MHz ...

http://www.ebay.com.au/itm/291090719893 ... 1423.l2649

Looks like full circle, is that Adam's plots in that item description?

Owen

[VK4GHZ]

Off topic:

Looks like full circle, is that Adam's plots in that item description?

Yes, those are my photos that have been stolen, (along with selected words, and Wayne's graphs), and are being used without authorisation for fluke.l's financial gain.
I knew there was a reason I started watermarking my images.

[VK4ZEJ]

Hi All,

Thanks for your thoughts and ideas.

The Ace Technology or High Gain Telecom relays I think seem to be the go. Have noticed on both of these that they have 4 ports and run on 20 - 30 V.

Is it necessary to have a connector in all 4 ports for them to work properly?
and,
As the LNA is designed to operate on 12V can a DC-DC step up converter be use piggyback style to supply the correct voltage for the relays?

Thanks in advance for your assistance.

Eddie

[VK2GOM]

Simplest way to use 28V relays at 12V. I did build my own, but these will save a bit of messing around.

http://www.w6pql.com/12_to_28v.htm

73 - Rob VK2GOM / GW0MOH

[VK2GOM]

...also a DIY solution is on page 2 of this document.

10GHz guide.pdf

(158.49 KiB) Downloaded 345 times

73 - Rob VK2GOM / GW0MOH

[VK5ZD]

Even simpler is one of the numerous boost converters available on eBay.
E.g. http://www.ebay.com.au/itm/151196792092 for $2.72
At that price it's hardly worthwhile building your own unless you already have all the necessary components in your junk box.

[VK4GHZ]

Even simpler is one of the numerous boost converters available on eBay.
E.g. http://www.ebay.com.au/itm/151196792092 for $2.72
At that price it's hardly worthwhile building your own unless you already have all the necessary components in your junk box.

Where are the Like or +1 buttons!

Yes, unless you have a compulsive need to constantly reinvent the wheel to occupy an abundance of spare time, these are the way to go!
Purchased 5 pcs of the identical same unit, just last week, for less than $13.
http://www.ebay.com.au/itm/400550995487 ... 1439.l2649

[VK4EA]

Make sure you take a look at the output under load, with a CRO. Most of the ones I have need an extra inductor and cap to quiet them down.

Sent from my MZ601 using Tapatalk

[VK4ZEJ]

Even simpler is one of the numerous boost converters available on eBay.
E.g. http://www.ebay.com.au/itm/151196792092 for $2.72
At that price it's hardly worthwhile building your own unless you already have all the necessary components in your junk box.

This is the type of thing I was thinking about. I have just ordered one whilst I think what type of relays to buy. Thinking of the High Gain Technology ones like http://www.ebay.com.au/itm/301014854971 ... 1423.l2649.

Eddie

[VK3QI]

Hi,

I can confirm everything that has been said about the Blue Relays currently available on Ebay, together with the voltage boost devices.

Attached is a picture of my dual band 1.2 and 2.4 masthead preamp which uses the blue relays and the voltage boost devices.

VK3QI VK3ER 1.2 and 2.4Ghz masthead preamp

Power wise, the preamp switches 400 watts PEP on 1.2 Ghz and 200 watts PEP on 2.4Ghz (less the cable loss in 6 metres of LDF 450)

As used extensively in the VK3ER/p field day setup.

Cheers
Peter VK3QI