G4BAO.COM
Microwave Amateur Radio Station, Waterbeach. 8km North Of Cambridge JO02cg
To Contact me:
Skype johng4bao
E-mail john at g4bao dot com
QTHR
Welcome to G4BAO's Amateur Radio Website
Microblog, 8th February 2010
Latest News
PA mod kit The mod kits were posted today, along with a couple of wideband amp kits for people who also had PAs, so you should be receiving a small brown envelope soon!
You should already have the mod details as an attachment to the email I sent out, or you can download it from here.
24GHz at G4BAO My new transverter is now complete and tested it, just under a watt out at the waveguide, and sub 4 dB noise figure. It just needs boxing up and putting outside. I've decided to go for a G4HUP DDS as LO source to drive the DB6NT multiplier and act as a high side LO for a 432MHz IF with the Thales 23GHz transceiver unit I got from EBay. I will publish details of the whole transverter here in due course.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Wideband Amplifier It looks like the wideband amplifier and bias tee article will be in March Radcom. I received the galley proofs this weekend and they have the March date on them. Kits available now, see the "for sale" page for details.
GB3CAM update. James, G3RUH has kindly donated one of his excellent GPSDOs to the beacon project (see his website for details). I will be evaluating a UKuG "reverse DDS" board to lock the DISTAW oscillator to the GPSDO. Watch this space for more details.
1.3GHz PA project - MOD KIT.
I have produced a FREE mod kit for the PA that fixes a potential stability problem. Everyone who bought a kit online should have received an email with details, and I will be sending them out early next week. If you bought a kit from me "in person" and have not received the email. Please email me with your address and I'll add you to the list.
I'm sorry I can only supply kits to people who bought my kits, but the mod components cost a few pence, are easy to fit and are strongly recommended.
Availability of kits I now have more plastic MRF9045 devices so kits are still available and all kits will now be supplied with the mod components.
Same deal, £65 for a full kit or £27 including return postage to replace device, repair and check out your dead PA.
My pair of 'BAO PCBs has been updated with the mods and is still doing sterling service here on 23cms. 85 Watts out and going strong. Brian, G6HFS is also building a "pair" in the new year, combined using the W6PQL hybrids and I hope to write up his amplifier here soon.
I still have a few complete and tested "prototype" amplifier boards for sale in the Jumble Sale pages. These are kits I've made up to try different devices, bands etc. If anyone is interested in purchasing these, email me for details.
I will continue to ship the kits without devices or heatspreaders if you can find your own. Look on the "for sale" pages for prices of kits without devices.
Wideband Amplifier project and bias tee, kits now available.
Minikits consisting of a PCB and all the components. See the "For sale" and download pages for details.
Bias tee kits currently half price due to me making the PCBs 4mm short of a standard Schuberth box...... D'Oh! Email me if you want a kit.
Below are typical performance plots.
In brief, the design covers 30MHz to 3GHz, with a sub 3.5dB noise figure and 20 dB gain over 30MHz to 500MHz. Above 500MHz the NF and gain drop off somewhat, but still has under 5dB NF and 19dB gain at 3GHz.. Its maximum output power is +10dBm, and third order intercept around +30dBm.
The bias tee is designed to power the preamp or similar low-power devices.
Bodger's Guide #4 I have added a new "Bodger's Guide" detailing my modifications to use a "useless" Mini circuits ZAPD-1 500MHz to 1GHz 3 dB power splitter in to a resistive splitter covering DC to over 4GHz. This article is based on surplus that has been kicking around at rallies for around a fiver each.
See the Downloads page for details.
Coming in the New Year As it's time for New Year resolutions, here's what to expect from this Website in the New Year.
"The 4CX250 killer" In my campaign to remove dangerous PSUs from Amateur shacks, I hope I have now sounded the death knell for the 2C39 with my cheap 23cm LDMOs PA.
I thought it was about time I killed off the 4CX250 for 2 metres and have just tested the first prototype of a quarter kilowatt amp requiring just half a watt of drive and a 50 volt supply. It's a single stage amplifier based on the Freescale MRF6V2300N. which costs around $85 from Richardsons Electronics. Not a final design by any stretch yet, but I should have a "proper" PCB done in January so watch this space.
I should point out now that this will not be a project for the feint hearted or the terminally clumsy, due to the device cost and its vulnerability in use. ( I have destroyed 3 of my 5 samples during development) For this reason, I will NOT be doing full kits nor supplying devices. That said, if all goes well, the design is reproduceable, and there is sufficient interest I will be happy to get a batch of PCBs made for experimenters, but if you blow up your device don't come crying to me!
Waterbeach in the Winter
Floods
