A FOOLPROOF ANTENNA SWITCH

[glovisol]

It really depends if you are using (A) one antenna to feed the three Inputs of the RSP inputs, or if you are using (B) a different antenna for each input.

In case (A) only one switch is required and you could find useful information here:

https://www.sdrplay.com/community/viewt ... f=5&t=3723

In case (B) you should use one switch for each antenna input.

[Gene_50]

I really like this...it appears someone went to the effort to mak a circuit board...is it available??

thanks, Gene

[glovisol]

Gene,

I bought the relay complete with its small PC board on ebay, obviously made in China. Probably you can find one there as well!

glovisol

[glovisol]

I think I have hallucinations here..... one hour ago I saw a post by Ian1951 warning about dry relay contacts (not the case here) and I wished to reply and now........ZIP BANG the post has disappeared! Must be the heat playing tricks on me: I have 39 °C around me and the air out of the cooling vent of the PC must be over 60°C: better switch off!

glovisol

[glovisol]

Well, now the post by Ian1951 after misteriously disappearing, has re-appered and I can reply.

The problem of dry contacts becoming insulated in the long run is caused by oxidation. In relays switching small or negligible currents and exposed to the atmosphere, this used to be a serious problem in the fifties and sixties of last century and still is a problem if the contacts are not insulated from air.

The encapsulated relays shown and tested in the reference proved to deliver excellent and faultless service because the danger of contact oxidation is eliminated. The relay I used in my switch is of the encapsulated type, so this danger is not present.

But, apart from this, my foolprof antenna switch may handle RF current that can approach one amp when switching transmitter power, so once again there is danger of contact burnout for too much current...e.g. the other way around.

glovisol

[Mike2459]

After reading the reference material provide by Ian1951, IMO the title of this post should be changed to 'A Fool's Antenna Switch'. And yikes, hanging this switch from the SMA connector of the radio's plastic case sends chills up my spine.

[glovisol]

After reading the reference material provide by Ian1951, IMO the title of this post should be changed to 'A Fool's Antenna Switch'. And yikes, hanging this switch from the SMA connector of the radio's plastic case sends chills up my spine.

Mike,

I do not know why one should hang the switch directly from the RSP SMA connector. Coaxial cables are readily available. Or why hanging it anyway should provoke chills up the spines of the beholders (a new type of air conditioner, maybe?). The reference material by "departed" Ian1951 has no bearing at all on the matter at hand, as I have explained already and is on par with the now self-eliminated, torrential posts about lightning dangers on USB cables by another "departed" guy, namely Nullouser00. In fact if you carefully read the referenced page by W0QE, you realise that indeed encapsulated relays are immune from the dreaded effects described by Ian1951.

Apart from this, it is evident that, declaring that several participants of this thread, who contributed to its development and the undersigned are "fools", is just the way to try and provoke another unnecessary and damaging crisis thread based on nothing.

Please stop this, nobody is hating you and as Tech_Support has reiterated many times, we are here to share and help each other, not to fight....

Gianfranco

[vk7jj]

"General Purpose relays are just that general purpose."

Hi Mike, making generalisations tells us nothing at all about any particular relay.

The relay pictured is not an unbranded unkown it is branded "Songle" and is said to be sealed.

Have you had a go at finding the specs of that relay and telling us whether or not it is suitable in your view?

There are very many Songles about, I use them for a range of purposes as they are widely available with various on-board low level drivers suitable for the Raspberry Pi control systems I build, they are outdoor systems so I was happy to see know they were sealed but I to what degree I don't know.

And as Ian hinted, it appears gold contacts are not necessarily as worthwhile as they might sound, eg. I found a few comments in this article interesting:

https://www.findernet.com/en/unitedstat ... -it-matter

Regards, Phil

[Tech_Support]

Once again, I have had to delete posts that I feel are inflammatory or likely to raise personal tensions. It is a great pity because this debate has been interesting and informative and in my view it is more educational when people are not actually all agreeing. Debate and disagreement feeds new knowledge as long as it doesn't become personal.

Once again I am issuing a plea to please avoid personal attacks or anything that may be perceived to be insulting.

Thank you

Tech_Support

[glovisol]

Thanks again, Tech_Support, for defending our Forum,

Gianfranco