Any interest in a transverter for the LOW bands?

[VK2CSW]

To me 600m seems more like "real ham radio" than microwaves (had to put some sort of controversial comment in).

So if it is real ham radio then I guess phone and digital is out? I mean CW is the only real radio, right?

[VK4WDM]

Hi Colin

Don't arc that one up. Unlike the microwavers, the CW guys don't have a sense of humour.

I just put the comment in because people seem to expect me to be controversial!

Now, back to the topic!

73

Wayne VK4WDM

[VK5PJ]

Hi Graeme and others,
I would be cautious about selecting a 1st IF anywhere in this region of HF (10MHz), there are some VERY strong HF broadcasters in this region and you will have a great deal of difficulty excluding them from your IF chain.

In Alice Springs I had a converted Philips FM1680 on 52.525 FM in the shack, most evenings the mute would open and there would be Radio Australia from Shepperaton with the standby programming tune (Waltzing Matilda). Their TX freq turned out to be a -2n image of the 2nd IF: 455KHz, away from the 1st IF of 10.7MHz and no matter what I tried I could not get rid of it. While the front end of the 1680 was quite tight there always seemed to be a path for Radio Aust to get in there.

Regards,
Peter, vk5pj

[VK2AAH]

Well the old AWA bases were much the same... quite often I had reports of them picking up short wave broadcasters.... I first thought they were pulling my leg until I drove up to Warialda and sure enough come sunset in came Radio Australia loud & clear.

Cheers


Richard
VK2AAH

[VK3ALB]

Perhaps 20m or the lower part of 10m would be a better IF choice?

[VK3ES]

Sounds to me like 10m might be the best IF band to use. It's away from the shortwave broadcasters and all radios can transmit in the band. You could even use a modified CB. I think it's the only HF amateur band where you could have the LF frequency equal the fractional part of the displayed HF frequency, ie 472.0 kHz would be displayed as 28.4720 MHz.
Of course you can't use a 10MHz LO directly but you could generate it from 10MHz using a simple direct synthesis scheme, eg:

(10MHz x 3) - (10MHz / 5) = 28MHz

This would require a mixer, divider and some basic filtering etc. I suppose you could make the LO board separate from the transverter, giving people the option of using a crystal oscillator or a GPS derived 28MHz LO.

Andy VK3ES

[VK4WDM]

KISS principle please!

What we need at this stage is something in kit form that is quick and easy so we can get some RF out on a new band.

My aim is to get local hams interested enough to do some building (and most of them are not experienced builders) and get a local net going.

Refinements can come later.

73

Wayne VK4WDM

[VK3XDK]

Yes If I were to put something together, It would certainly be a separate LO. Gives flexibility!

I've ordered a few coils ect, hopefully start playing in the coming weeks.
Still havnt been able to source mixers, im thinking minicircuits ADE-1

[VK4TI]

Yes If I were to put something together, It would certainly be a separate LO. Gives flexibility!

I've ordered a few coils ect, hopefully start playing in the coming weeks.
Still havnt been able to source mixers, im thinking minicircuits ADE-1

Perhaps ? http://www.southgatearc.org/news/july20 ... z_band.htm will offer some ideas ?

[VK4TIM]

I've used the NE612 mixer IC before to mix 455 kHz down to 12 kHz for PC soundcard DRM reception, and the same IC is used on the FM band expanders to shift FM radio down to the 76-90 MHz band for Japanese import car radios, and they seem to work.

These devices seem to work OK, I'm not too sure what the noise figure of the device is like, but it might be OK to use for an HF transverter.

I kniw someone who made his own 2m to 6m transverter, he used an SBL-1X mixer there I think.

[VK3XDK]

Thanks for the links,
I'm hoping to have a bit of RX gain as well, which will need a 2-way mixer (and some radios dont go down as far as 472khz, so RX conversion is needed)
Not sure IF the G3XBM circuit is suitable for SSB? may be non-linear ?
I am looking a similar output devices though.

[VK4WDM]

G3XBM used OPERA to exchange reports

Does that mean I have to learn how SING to use 600m?

If you think my CW is bad enough, wait until you hear me sing

73

Wayne VK4WDM

[VK3PF]

Hi Graham,

Thanks for the links,
I'm hoping to have a bit of RX gain as well, which will need a 2-way mixer (and some radios dont go down as far as 472khz, so RX conversion is needed)
Not sure IF the G3XBM circuit is suitable for SSB? may be non-linear ?
I am looking a similar output devices though.

From what I have been reading, one needs to be careful with regards to Rx gain before a mixer to transvert with the LF bands.It seems that a key starting point is some filtering to attenuate the MF broadcast stations (531-1600 odd kHz) , otherwise the entire system can potentially be overloaded.

Just some random thoughts. Still trying to organise VHF/UHF antenna masts here after 2.5 years at the new location. LF may need to wait a little longer!

I agree that a linear circuit might have more flexibility, but have not investigated further as yet.

Cheers,

Peter VK3PF

[VK3XDK]

Yes, I've been working on some tuned preselectors.
Still deciding if I'm going to go with a MMIC front end (good performance and easy but 50ohm (not as good for loaded Q on the preselector)) (but still very selective)

Or a fet or bjt front end (I can have a higher loaded Q for even better preselection, but more complicated (mainly for me!))

[VK3XDK]

Allright,
Been very busy and have come up with a draft. (see attachment)
Very high dynamic range front end with good preselection. Should put out about 10Watt (going on my tests)
There will be fine tuning (mainly with component values)

I have also put together a pcb layout and are getting initial quotes (FR4 1.6mm)

LO can be an on-board can/smd oscillator OR external. Users can choose their IF (by changing the LO frequency)

Likely to be more than my estimated price (It became a bit fancier!!). Will be less than $100 though.

Interested in comments/feedback.

UPDATED (more changes to come, I'm sure!)

Schematic is now obsolete, and has been deleted (see more recent posts for the updated version)

[VK3XDK]

And a layout (see attachment)

Ive used mainly 1206 size components, they are relatively large (when it comes to smd) to make it easier.

[VK2GOM]

I can't see the attachments. I'm logged in. Can anyone else download them?

73 - Rob VK2GOM / GW0MOH

[VK4TI]

I can see it's a tiff but cant download

[VK2ZRH]

Right click on the link and select "View image".

73, Roger Harrison VK2ZRH

[VK4TI]

Right click on the link and select "View image".

73, Roger Harrison VK2ZRH

Done tnx