PCS-Electronics

I am looking for schematic diagram of micro UHF transmitter(bug), frequency band near 400MHz (quarz controlled) ,range near 500m or more, professional SMD design, small size, battery life 10-20 days. Could someone advice good solution?

mildex

https://www.pcs-electronics.com/product ... tter-kits/

I need more professional and more quality bug then listed here, I need Schematic diagram.

mildex

You must be kidding. The PRO version is exactly what you're
looking for, gives up to 2km of range with 20 days of battery
life. Its crystal - PLL controlled. And it is UHF.

You are right about one thing, though. Schematic is not available
for this unit.

I'd always prefer build unit independently, this allows choose/customize some options, case size, power etc. Why do not make the schematic diagram AVAILABLE for community? This topic calls "User share experience..." Community could discuss its, maybe, even to improve some parameters. There many good specialists among a community.

mildex

pcs wrote:You must be kidding. The PRO version is exactly what you're
looking for, gives up to 2km of range with 20 days of battery
life. Its crystal - PLL controlled. And it is UHF.

You are right about one thing, though. Schematic is not available
for this unit.

Did you make your TV set yourself also?

No, I do not make my TVset myself. This is other thing, its outside of my interests.

pcs wrote:Did you make your TV set yourself also?

The BUG PRO I is a product of another company of my very close
friend. He does not want to publish a schematic.

BUG PRO I is a pretty unique piece of transmitter and I don't see
a reason why he should give away the schematic. He would be crazy
to do so. Also, it is entirely SMD with some really hard to get parts,
custom ordered Xtals etc. So it is not suitable for a homebuilder as
such. Just making the PCB is very complex at this frequency.

Here is description and schematic of good VHF bug
http://hem.passagen.se/communication/buggtx.html
You can use it for free.

pcs wrote:The BUG PRO I is a product of another company of my very close
friend. He does not want to publish a schematic.

BUG PRO I is a pretty unique piece of transmitter and I don't see
a reason why he should give away the schematic. He would be crazy
to do so. Also, it is entirely SMD with some really hard to get parts,
custom ordered Xtals etc. So it is not suitable for a homebuilder as
such. Just making the PCB is very complex at this frequency.

Hi!

Thanks for the schematic, I'll add it to our schematic section.

I have a few suggestions:

1.) Only one AF stage should be enough for this

2.) The problem with this setup is that it can't produce wideband FM,
usable at the RM radio band (75KHz swing).

3.) The second problem is that to produce UHF signal with this method
you require a large number of multiplying stages which will need to be
aligned (tuned). Alignment can be very touchy mechanically and a fall
on the floor can de-tune the trimmers. It is not a very practical approach,
but it does work.

4.) Another problem with a large number of amplifier stages is that
a intermediate signal can feed through to the output stage. This makes
the usual filtering with LPF unpossible (since signal is under the carrier
in frequency).

Other than that, it can be made to work for NBFM applications nicely.

Otherwise, your website is really cool. Feel free to contact me with any ideas or questions at any time (use email). We might even find a way to colaborate in some way some day.

Hi,

This VHF transmitter author, as well as mentioned website owner is Daniel Norman. I just showed his transmitter as an example.

mildex

pcs wrote:Otherwise, your website is really cool. Feel free to contact me with any ideas or questions at any time (use email). We might even find a way to colaborate in some way some day.

Ah, it is not you? It sounded as if it was you from your post.

Never mind.

Hi,
could you accomplish this your suggestions into improved schematic of this transmitter(for 400MHz) and make it available?

mildex

pcs wrote:Hi!

Thanks for the schematic, I'll add it to our schematic section.

I have a few suggestions:

1.) Only one AF stage should be enough for this

2.) The problem with this setup is that it can't produce wideband FM,
usable at the RM radio band (75KHz swing).

3.) The second problem is that to produce UHF signal with this method
you require a large number of multiplying stages which will need to be
aligned (tuned). Alignment can be very touchy mechanically and a fall
on the floor can de-tune the trimmers. It is not a very practical approach,
but it does work.

4.) Another problem with a large number of amplifier stages is that
a intermediate signal can feed through to the output stage. This makes
the usual filtering with LPF unpossible (since signal is under the carrier
in frequency).

Other than that, it can be made to work for NBFM applications nicely.

Unfortunately I do not have time right now, perhaps some day.

What would i have to change on the transmitter at
http://hem.passagen.se/communication/buggtx.html
to transmit at the 2.4 ghz range.

my goal is to make a bug i can use about 50 +\- meters