Posts by G8UGD

Why not just set up a chat group in mumble if speech is what you wish for then participants do not need to have another uplink channel.

But the WB text chat channel is good enough for many when listening to the transmit stations audio. If there are two many ways to chat, which one becomes the preferred and which ones get left behind, it can become a situation where some use one system and some another and it looses cohesion.

Keep it simple and limited would be my thoughts, I have asked several questions on the WB Chat and always had a response, I am not yet able to transmit pictures, but can give reports on stations OK.

I am still waiting for mine to arrive so I can size up for a heat-sink. Is there any chance you could let me know the board size so I can start looking for a suitable one?

Are you planning on running two boards in parallel or just building a main and backup PA. I appreciate that the cover will be difficult to split.

This got me thinking so I have just done a test without and with the BPF. It is not the local osc that is coming through, but with injection freq of 144Mhz you are also getting an output of -40dB of LO -144Mhz also seem to be getting the output frequency of 2400 + twice 144 MHz, see below.

First pic is without the filter and the second with the filter.

Sorry they are a bit blurry as taken with phone camera.

Vertical is 10 dB per division and horizontal is 100MHz per division centred on 2400MHz. So the trace is going between 1900Mhz to 2900MHz

Test set up is probably not the best, but using output from a 30 dB direction coupler to a 50 Ohm load with a further 20dB on the analyzer input to ensure I am not overloading. In the first picture you can see a small amount of Wi-Fi breakthrough as I have an extender within 1 metre of the gear.

So I would always use a BPF no matter what.

I am using 144 MHz so the LO is 2256MHz. This was around -45dB'ish on carrier and as the user guide says stick a notch there.

My BU500 arrived and I have gone a slightly different route. I have kept the original heat-sink on the unit and added another to fit. Used a thermal pad between the two, then stuck on a small fan to blow air through. I will be doing a simple analogue control for the fan to reduce the noise but it was on for over 6 hours yesterday with no noticeable increase in temp to the touch.

I was surprised at the output power and the meter has been set for full scale at two watts. Although the local oscillator leakage is not bad it is there, so I have re-tuned a 2500 to 2690MHz filter I picked up from a rally to cover 2.4GHz. It has a low end notch of around -70 dB on the LO output. It appears to be spectrally clean on my old analyzer so I am happy with that. I had one contact on air last night and it seemed to be fine.

That is good news, but I thought the 2m section was a diversion for the 23CM's band and the new European GPS satellite service Galileo. That will have some major impact on navigation users.

Unless I have been reading the wrong articles, brain fade etc.

Email on it's way.

I would rather have a go at building/modifying something then just going out and buying it. But I will buy to initially get on the air, just wish to improve things without spending too much money.

I guess my question is is anyone using the same amps?

They are advertising a PA with 2x BLF7G22L-130 are these OK for a novice to start with trying to build up some power for TV or are they what I may call expertise needed?

I have limited resources, I can run to a power meter, 30 dB coupler but my speccy analyzer has just thrown a faul;t probably the attenuator.

For the price they seem to be worth an attempt?

Adrian

Last, does the Title always go to caps?

Quote from PA3FYM

G8UGD In most cases the sentence concerning SDR Console is followed by "locked on the PSK-beacon" ; -)

True.

I am not having a dig, just do not understand the purpose of the thread.

I have been away from amateur radio for years, I did plenty of Q and A on the web, or email with all nationalities and I am always impressed by everyone's ability to converse. Unfortunately I only speak English and can feel I let others down. I am soon about to set foot on the narrow band section, I will make mistakes, get mixed up and say stupid things at times especially when listening to oneself half a second later! How do you get used to that?

I will add mine:

"Using a BU500 up-converter" "SDR Console on receive"

I will be honest and say I do not understand the idea of the thread, it seems to be a way of poking fun at ops?

I know this is an old thread, but I have one of the same units, an older synthesised device built around a MC151xx device with an EPROM that holds the programming data, for the APT format 2.4KHz tone system.

I may have some informations/circuits somewhere on the unit and will try to find it just in case the original poster is still wanting information. No gaurantees.

Cutting small groves in the track and fitting caps or even a resistor would still be possible. I measured the input current at just over 15 Volts in to the step up unit when transmitting it was 0.96 Amps so the unit is dissipating 15 Watts. I have a small fan I will connect to the fins if I can figure a mounting method.

I have no larger amps at present, so just hope to get on SSB initially, need to test the POTY next.

G8AGN I saw your response this morning so I set about putting something together as yours was the second one indicated with direct connection. I eventually etched a board, not done that in a long time, I did not follow any rules as I have no software for this just made something up. This is the board mounted on a heat sink.

I have not put +5 dBm into the unit yet as the Hackrf I have limits at around -2 dBm but it looks like it has 26 or 27 dB gain. So for a first attempt at this in a very long time I am happy.

Thanks all for your assistance.

Thought I should get the title correct at least.

F1FAQ that is interesting, there may be caps on the device, just does not show or give any suggestions by way of a development circuit or similar.

Thank you for the reply, I have been searching for practical circuits using the device without success. So nice to know from a practical point of view.

Thank you.

I would appreciate knowing of the input and output to the MH21336 can be direct to co-ax or does it need to go via caps to provide DC isolation? I am guessing via caps but would like to make sure before I start.

Adrian

OK, I had assumed there would be some drift over time, otherwise they would not included the external port. For RX I would initially be relying on the SDR console locking to the beacon to remove the LNB drift, all guesswork until I actually get the unit and try it.

The 5MHz oscillator I have has a spec of <=2 x 10^-9ppm over -30 to +70 degree C, which I believe is better then most of the small TXCO's. Awaiting a MHL1336 and hope to provide a small 3 watt type amp and see if the will suffice.

Hope to meet up on air!

Adrian

I am a beginner here and hope to be able to make SSB contacts at some point. I have ordered the BU500 and notice in some of the information that the reference can either be 10MHz or 26MHz. I was wondering if there is any option to select other standards. I have a 5MHz crystal oven style frequency standard that was used for quasi-sync PMR systems at UHF and would like to use that. I guess if not I could add a frequency doubler to go from 5 to 10 MHz. The 5 MHz standards crop up quite often.

Adrian