Diseqc switches
 

My previous satellite setup had a Smart Oxid quad LNB on 28.2E

two of the LNB outputs fed a dual tuner DVB-S2 tuner in PC
other two LNB outputs headed off to down to lounge via Blake starBox

Recently I've added a Smart Oxid single LNB on 19.2E

Initially I connected the new LNB's output direct to one of the tuner
card inputs, I could scan for and receive all the expected channels from
19.2E

So, happy that I'd found the correct satellite, but before final
positioning and tweaking, I inserted

Smart SUS4 2x1 diseqc switch

With the output of the single LNB on port1 of the switch
and the first output of the quad LNB on port2
the output of the switch goes to one of the tuner card inputs

Reconfigured the PC's software (mythtv) so it is aware the switch is
there, and which LNBs connect to which ports.

When I tell it to scan 28.2E, it selects port 2, finds the 28.2E
transponders/channels during the scan, and is able to receive them.

When I tell it to scan 19.2E, it selects port 1, it does find various
19.2E transponders/channels during the scan, but jumbled in with them,
it sees 28.2E transponders/channels too, afterwards it isn't able to
receive the 19.2E channels.

I get the same "jumbled" results when using w_scan and scandvb instead
of mythtv.

I also tried NOT telling mythtv about the switch, so that (AIUI) without
diseqc commands the switch will default to port1 and the PC should
simply see the 19.2E signal, this gives the same jumbled result.

Since today has been wet'n'orrible I've not been out to fiddle with the
dish and disconnect the switch, but does this sound like a faulty switch?

What are the different committed/uncommitted switch types, would getting
that wrong give the results I'm seeing?

Diseqc switches
 

On 18/03/2012 19:29, Andy Burns wrote:
My previous satellite setup had a Smart Oxid quad LNB on 28.2E

two of the LNB outputs fed a dual tuner DVB-S2 tuner in PC
other two LNB outputs headed off to down to lounge via Blake starBox

Recently I've added a Smart Oxid single LNB on 19.2E

Initially I connected the new LNB's output direct to one of the tuner
card inputs, I could scan for and receive all the expected channels from
19.2E

So, happy that I'd found the correct satellite, but before final
positioning and tweaking, I inserted

Smart SUS4 2x1 diseqc switch

With the output of the single LNB on port1 of the switch
and the first output of the quad LNB on port2
the output of the switch goes to one of the tuner card inputs

Reconfigured the PC's software (mythtv) so it is aware the switch is
there, and which LNBs connect to which ports.

When I tell it to scan 28.2E, it selects port 2, finds the 28.2E
transponders/channels during the scan, and is able to receive them.

When I tell it to scan 19.2E, it selects port 1, it does find various
19.2E transponders/channels during the scan, but jumbled in with them,
it sees 28.2E transponders/channels too, afterwards it isn't able to
receive the 19.2E channels.

I get the same "jumbled" results when using w_scan and scandvb instead
of mythtv.

I also tried NOT telling mythtv about the switch, so that (AIUI) without
diseqc commands the switch will default to port1 and the PC should
simply see the 19.2E signal, this gives the same jumbled result.

Since today has been wet'n'orrible I've not been out to fiddle with the
dish and disconnect the switch, but does this sound like a faulty switch?

What are the different committed/uncommitted switch types, would getting
that wrong give the results I'm seeing?

i have seen this before. its basically poor inter-satellite isolation
within the diseqc switch

change the switch for a good quality one. Avoid technomate TM4-s's

The best I've personally worked with in the 4 port global communications
switch. I do not know if these are still in production.



Regards,

Stephen

Diseqc switches
 

Stephen H wrote:

Andy Burns wrote:

When I tell it to scan 19.2E, it selects port 1, it does find various
19.2E transponders/channels during the scan, but jumbled in with them,
it sees 28.2E transponders/channels too

i have seen this before. its basically poor inter-satellite isolation
within the diseqc switch

Well, it certainly was a cheapy, but Smart is at least a name I
recognised, claims 25dB inter-LNB isolation.

change the switch for a good quality one. Avoid technomate TM4-s's
The best I've personally worked with in the 4 port global communications
switch. I do not know if these are still in production.

I can see Global Invacomm 2x1, but it only claims same isolation as the
Smart one I have.

Diseqc switches
 

Andy Burns wrote:
I get the same "jumbled" results when using w_scan and scandvb instead
of mythtv.

I also tried NOT telling mythtv about the switch, so that (AIUI) without
diseqc commands the switch will default to port1 and the PC should
simply see the 19.2E signal, this gives the same jumbled result.

Since today has been wet'n'orrible I've not been out to fiddle with the
dish and disconnect the switch, but does this sound like a faulty switch?

It certainly sounds to me like a faulty switch.

What are the different committed/uncommitted switch types, would getting
that wrong give the results I'm seeing?

An uncommitted switch wouldn't respond to the diseqc 1.0 switching codes
that committed switches respond to, but they also wouldn't jumble up the
signals from two LNBs. I've used both 2-way and 4-way Konig switches
without any problems - about £6 through Amazon for a 2-way.

Diseqc switches
 

On 18/03/2012 20:38, Andy Burns wrote:
Stephen H wrote:

Andy Burns wrote:

When I tell it to scan 19.2E, it selects port 1, it does find various
19.2E transponders/channels during the scan, but jumbled in with them,
it sees 28.2E transponders/channels too

i have seen this before. its basically poor inter-satellite isolation
within the diseqc switch

Well, it certainly was a cheapy, but Smart is at least a name I
recognised, claims 25dB inter-LNB isolation.

change the switch for a good quality one. Avoid technomate TM4-s's
The best I've personally worked with in the 4 port global communications
switch. I do not know if these are still in production.

I can see Global Invacomm 2x1, but it only claims same isolation as the
Smart one I have.



I used to have 3 single LNB's via a single Global 4 port switch. I
changed the single LNB's for quad LNBs and added 3 technomate switches
to feed additional receivers.

Any receiver connected to the technomate switches exhibited the problem
you described. The one attached to the global switch was fine. Swapping
the receivers around proved that it was the 3 technomate switches at
fault. Anything attached to the global switch was fine and could switch
satellites no problem.

I ended up going to 3 quattro LNB's and a 17x16 multiswitch. All my
probs went completely. The technomate switches were cheap, I got them
for a fiver each. The global switch cost me 20 quid in the first place.

HTH,

Stephen

Diseqc switches
 

Andy Burns wrote:
Stephen H wrote:

Andy Burns wrote:

When I tell it to scan 19.2E, it selects port 1, it does find various
19.2E transponders/channels during the scan, but jumbled in with them,
it sees 28.2E transponders/channels too

i have seen this before. its basically poor inter-satellite isolation
within the diseqc switch

Well, it certainly was a cheapy, but Smart is at least a name I
recognised, claims 25dB inter-LNB isolation.

change the switch for a good quality one. Avoid technomate TM4-s's
The best I've personally worked with in the 4 port global communications
switch. I do not know if these are still in production.

I can see Global Invacomm 2x1, but it only claims same isolation as the
Smart one I have.

I suspect that many of the different brands come from the same
manufacturer. Price isn't necessarily an indication of quality.

Diseqc switches
 

John Legon wrote:

I suspect that many of the different brands come from the same
manufacturer.

Several of the ebay/amazon ones do bear a family resemblance, but some
are obviously different.

Price isn't necessarily an indication of quality.

Bearing in mind your other reply, a while back when I ordered a Konig
satfinder, what arrived looked the same but was badged different anyway,
I didn't really object.

I've just had a look, and the Konig switch is identical to the Smart
switch I have anyway.

I've just had a thought ... I do tend to leave a long tail on the inner
conductor when making up F connectors, wonder if one has poked somewhere
it shouldn't?

Diseqc switches
 

Stephen H wrote:

Avoid technomate TM4-s's

Hmm, searching for those, they do like like yet another rebadge of the
4-port big brother of my 2-port one ...

Diseqc switches
 

Andy Burns wrote:
John Legon wrote:

I suspect that many of the different brands come from the same
manufacturer.

Several of the ebay/amazon ones do bear a family resemblance, but some
are obviously different.

Price isn't necessarily an indication of quality.

Bearing in mind your other reply, a while back when I ordered a Konig
satfinder, what arrived looked the same but was badged different anyway,
I didn't really object.

Might be Konig, Labgear, SLX and a few others


I've just had a look, and the Konig switch is identical to the Smart
switch I have anyway.

No surprises there then! My Konig switches seem solidly made and the
4-way has been in regular use for a couple of years.

I've just had a thought ... I do tend to leave a long tail on the inner
conductor when making up F connectors, wonder if one has poked somewhere
it shouldn't?

The inner wire is usually allowed to protrude by about 2-3 mm beyond the
outer rim of the plug.

As a basic test that the switch is switching and not shorted between the
two ports, I would suggest measuring the voltage on the inner conductor.
This should be 13 or 18 volts when the port is selected, and 0.00 when
it's off.

Diseqc switches
 

John Legon wrote:

The inner wire is usually allowed to protrude by about 2-3 mm beyond the
outer rim of the plug.

I seem to remember I left one of them about 1cm.

As a basic test that the switch is switching and not shorted between the
two ports

The odd thing is that port2 appears to "leak" into port1, but not
vice-versa.

I would suggest measuring the voltage on the inner conductor.
This should be 13 or 18 volts when the port is selected, and 0.00 when
it's off.

Yeah, when it's less soggy I'll get on the roof (only the garage
fortunately) and have a look, easiest way to check the switching will be
to re-attach the satfinder which lights up when powered, while SSH'ed
over WiFi to the mythbox from a netbook.