Getting started, what other bits do I need? - Page 1
Forum section: electronics / rf-microwave

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 06, 2019, 11:58:25 pm
content: Hi,Putting the licence requirement to the side for now.A while back I got some Russian "ATMega2560 + 3.2" TFT LCD + Si5351" PCB's from pcbway to pad out an order. I grabbed a few of the IC's from digikey.My soldering has improved and I want to build this synthesizer, what other bits will I need to start receiving ham radio transmissions, I would prefer to get PCB's or DIY kits so I can build it up and keep the cost down, I guess I need at least a compatible transceiver, what should I get, any other electronics I need (not including an antenna, PSU and headset)?Thanks for looking.Richard

author: vk6zgo
author_rank: Super Contributor
timestamp: May 07, 2019, 01:53:42 am
content: Quote from: rthorntn on May 06, 2019, 11:58:25 pmWell, you don't need a licence for just listening.There are several ways to use your synthesiser in a receiver.(I assume you are thinking mainly about HF)(1) Build a complete receiver from scratch, either a Superhet or Direct Conversion.(see VK3YE's websitte for some examples of the latter).(2) Using a ordinary AM broadcast receiver as a tuneable IF, build up a converter using a balanced mixer & your synthesiser as the first local oscillator.ChristofferBhas has success with this method.(See his thread "Using an AM Radio as IF & AF stages..." starting about a month back in this sub forum.)(3) Using your synthesiser & a balanced mixer before the input of an VHF SDR dongle. (there is a ink to W2AEW's YouTube video showing this, in the thread referred to above.)Note:- Ordinary SDR "dongles" will allow you to listen to Hams on 2 metres 70cm, probably 6m as well.Not using your synthesiser, you could "butcher" the front end of an ordinary VHF FM broadcast radio to receive 2m FM.

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 07, 2019, 02:23:49 am
content: Thanks vk6zgo.Would the ubitx work with my synthesiser?If ubitx is what I need, ideally I would build starting with a fabbed pcb, is there a pcb only version of the ubitx, or gerbers that I could send to pcbway?Thishttps://lz1dpn.blogspot.com/2017/09/ubitx-ver-kmk-2017.htmlseems to show a PTH version, which is nice?It has a link at the bottom tohttps://github.com/LZ1DPN/uBitxKMK2017not sure if that has everything I need to get it fabbed though?Richard

author: vk6zgo
author_rank: Super Contributor
timestamp: May 07, 2019, 03:18:57 am
content: Quote from: rthorntn on May 07, 2019, 02:23:49 amI haven't had anything to do with the ubitx, but there should be quite a few Hams who have.Where in Oz do you live?I, as you've probably worked out by the "6" in my call sign, am in WA.There are still a fair number of Amateur Radio clubs in each Capital city, as well as some larger country regions.They may well have someone who is a "Guru" on that particular design.Will, VK6UU has made it a "labour of love" to copy & release on his website, issues of "Amateur Radio" Magazine from the first copy, up to the present.He has got up to 2012 so far.I think the ubitx is a bit newer than that, but maybe not.(I have a vague recollection of some reviews of the design in "AR".)Anyway, it is a great resource, if you have the time to browse through it.Have you had a look at eHam or QRZ.com, for any comments on the ubitx?They are both interesting sites, in their own right, & may be well worth visiting, in any case.P.S.:- I googled & found a plethora of sites all either referencing this radio, or dedicated to it.Our old mate VK3YE has quite a few YouTube videos on the ubitx, here's one at random.https://m.youtube.com/watch?time_continue=334&v=sXJmAhpAjeI&ebc=ANyPxKpJeIqwswctq7qliYy6aW7AL9CNsOLE3BGQ50dmjsETf70t7UH3m4INfWy6_mEhXXAX0cYe08G5lODNaTMBqgTBNpA0wg

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 07, 2019, 05:39:45 am
content: Thanks, I'm in Sydney, I'm thinking the MST3http://www.ozqrp.com/MST3index.html, thoughts?If it makes sense there are four filter sets to choose from:80M Filter Set 80M RX BPF, TX BPF and LPF for the MST340M Filter Set 40M RX BPF, TX BPF and LPF for the MST320M Filter Set 20M RX BPF, TX BPF and LPF for the MST317M Filter Set 17M RX BPF, TX BPF and LPF for the MST3Which filter sets are going to give the best bang for buck?Richard

author: Kalvin
author_rank: Super Contributor
timestamp: May 07, 2019, 07:38:22 am
content: uBitx comes with a Raduino board containing the si5351 synthesizer. If you want to get uBitx and start experimenting, I suggest that you should disable the TX (by not connecting the PA_PWR signal in connector P1) until you have obtained a valid ham license. Getting the license is not that hard if you decide to go for it.Edit:The main site for the uBitx with hardware description and schematics etc.:http://www.hfsignals.com/Unofficial (but great) information and support site for the uBitx:https://ubitx.net/Main messaging site for the uBitx:https://groups.io/g/BITX20

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 07, 2019, 09:03:10 am
content: Thanks Kalvin, I think I get it, the ubitx has relays onboard and so it can switch between multiple onboard RX BPF's, TX BPF's and LPF's?The ubitx circuit appears to have some performance issues (over the MST3) but the convenience for a beginner would make it a good choice and it looks like some of the issues can be rectifiedhttps://ubitx.net/category/hardware/harmonics-and-spurs/.The ubitx looks to be very hackable.Ordered.

author: Kalvin
author_rank: Super Contributor
timestamp: May 07, 2019, 09:22:36 am
content: I have uBitx V4 waiting for an enclosure and some relay swapping as mentioned in the ubitx.net site. The current V5 version should not have issues with the TX spurs, though. Yes, uBitx is very hackable as you may have already found out. It also contains required TX and RX filtering for the HF ham bands. For the price you will get a very decent HF transciver which can be hacked easily and repaired easily should you break something during experimenting.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 07, 2019, 11:29:29 am
content: Quote from: rthorntn on May 07, 2019, 05:39:45 amIf you start out in Ham Radio with a Foundation Licence ("F" call), you will be mainly using 80m & 40m, as 20m & 17m are not allocated to that grade of Licence, so the 80m & 40m filter sets seem the most appropriate.You can use the others to receive, of course.My knowledge of these devices is quite scanty, but the other posters have included quite a few good links.Being in VK2, you are pretty much "embarrassed with riches" as with your larger population, there are proportionally more Amateurs &, hence, clubs.There is one problem, which I just remembered.Foundation Licensees can only use Commercially manufactured equipment, so that pretty much rules out "Homebrew" or kit equipment.Maybe, just build it up as a receiver first, then try to go for the Standard Licence, bypassing the "F" call.I think you still have to do the Foundation practical tests, but your written exam is at the higher level.

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 13, 2019, 03:54:48 am
content: Thanks everyone.My uBITX arrived.What cheap options do I have for antennas, WAF is going to factor in here, so something up on the roof?

author: Kalvin
author_rank: Super Contributor
timestamp: May 14, 2019, 07:32:53 am
content: Since you are not allowed to transmit anything yet, you do not need anything special other than some kind of antenna for listening. For best receiver sensitivity you should build or buy something that is used by ham radio operators. After you have acquired a valid radio amateur license, you can enable the transmitter part of the uBitx. Then you typically want to have:- Antenna tuner for tuning the antenna and the feed line to match the 50 ohm TX impedance in order to mininimize the SWR.- A balun if you want to use a long wire antenna or symmetric antenna.- 50 ohm 20W dummy load for transmitter testing purposes.- Probably some ferrites for reducing any RFI interference etc.As you can see, as long you do not transmit anything, you do not need any special gear. All those items listed above can be built at home or can be purchased as kits or ready-made. Since the power level is around 10W or so, the parts should not cost too much anyway.About uBitx: Read the assembly instructions carefully, especially make sure the TX will not transmit accidentally when you power up the radio. If TX transmits when an antenna is not connected or the antenna is not tuned properly you may damage the power transistors in the TX. It is also advisable to add fuse to power supply line just in case. Happy building!