21st October, 2009:


Letter to interested parties...........


Hello all,

I am sending you this update as you expressed interest in the Combo PICaSTAR panel. I know a fair bit of time has passed and some of you are wondering just what is happening with this PCB.

This email is long, I hope it has all information you need. If not, email me.................. vk3pe@bigpond.com

As you may recall, earlier this year I made 5 prototype panels for the ComboStar and so far, 2 have been completed. My own (VK3PE) and Michel, F1CHM's. Of the remaining 3, Bill, VK7MX, has been constrained from completing his due to other commitments and the others have not yet started or have stopped construction, for unknown reasons.

Michel has reported no problems with his build although since I don't speak French, communication has been through Google Translate. Michel is a very experienced constructor and has also built a Picastar using my two previous PCB panels.

My own is used daily for listening mostly at the moment, while I do work on the PCB update and also integrate my Trxavrb PCB into it. (never enough time in the day!) On my prototype PCB there were a couple of minor issues with soldering provision for shielding around the BPF section on the prototype PCB but all else seems fine.

The prototype ComboStar used the PICnMIX interface but since then, Ian's (G3VPX) TrxAavrB graphical or character based LCD interface has been developing very fast and I believe is the better, more flexible, interface for new builds. It will though, be slightly more expensive to build, depending on your final display option. If you prefer the PICnMIX, then you would need to find a "spare" PCB from somebody who has the older panel #2. Either PICnMIX version "B" or Traxavrb simply interface to COMBO using 2 x 20 pin IDC cables for the majority of connects. Under the COMBO PCB, there are several coax cable interconnects for RF connections to the various circuit blocks.

So, the PICnMIX has been removed from the panel and in it's place, a basic Trxavrb PCB will be included. By basic, I mean that the keypad PCB's on that panel will not be included, for space reasons. That is not really a problem because there are other ways to include the same capability, without requiring PCB's. E.g., one can uses a 4x4 keypad in place of the 18 button key pad and use Encoders with push switches for the right hand 8 button keypad. (or any other switches that you like). Of course, if you elect to go with the colour TFT display or a 320x240 display with touch screen, then the switches are not needed.

The ComboStar panel is a Panel 260 x 410mm of several PCB's and will now include the following:-

1) Combo PCB, a large PCB that contains all of a PICaSTAR except for PA, LPF and Control (Trxavrb)
The COMBO section is about 260mm wide and 285 mm deep. You need about 30mm or so of height above the PCB. The 10M4D style crystal filter is about the highest component. All but a few bypass capacitors and the Audio Amp I.C. are mounted on the top of the PCB.
2) Opto tuning board. This PCB is for those home brewing the tuning encoder as per original PICaSTAR.
3) 20W PA, Steve's (G6ALU) proven 20W PA
4) LPF, Ray's (G4TZR) proven LPF design.
5) Trxavrb control board, basic version as detailed above.
6) Remote USB PCB for Trxavrb.
7) Ponyprog, small PCB to program the Atmel microcontroller devices on the Trxavrb interface.
8) Beeper, small PCB for 'beeping' out connections, checking for shorts etc
9) I2C Interface PCB. This is a basic version of Ian's serial interface to Trxavrb, which will allow expansion for those who wish to use other BPF or LPF configurations or add other switching capability to Trxavrb. Due to lack of space, only the PCA9555 driver chip is fitted. You would need to provide ULN2803 driver devices separately.

See Ian's web pages for Trxavrb interface description and pictures, set-up procedures etc.

PICnMIX interface board. (replaced by TrxavrB)
Ian's tuning Opto Interface PCB. This is not really needed, as Ian's configuration utility (Hobcat) allows a home brew tuning encoder to be specified without any further interfacing.

PCB CHANGES: Since the prototype ComboStar was made, I decided to make some other changes to the PCB and these are shown below, along with some of the "features" of the Combo PICaSTAR PCB.

These are:
1) Numerous little "tidy ups" of tracks, overlay etc.
2) LED indicators on the PCB for BPF selects, 10v supply, Rx and Tx 10V, DDS filter ON.
3) The Opto Isolator for PTT and KEY inputs in the DSP section is part of the PCB. While it uses an Opto coupler, it does not have the full voltage isolation it may be capable of due to tracking issues on the PCB.
4) Add dual footprint for the ADSP-2181 to give wider choice for buying this part
5) Fitted a 100nF capacitor in the Magic Roundabout RF in/out port.
6) DDS carrier is now integrated onto the PCB. However, the 28 pin socket remains of you want to experiment with other DDS devices etc. However no sub PCB is provided for that purpose.
7) Removal of PICnMIX allowed me to add Ray's (G4TZR) LPF board. This now means that the Combo Panel is a complete set of PCB's for a 20W Picastar (controlled by Trxavrb) No other PCB's are needed.

HOWEVER, I have costing on Steve's 140W PA PCB and will make a "package" of the ComboStar panel, PLUS the 140W PCB.
8) Provision for a "Harry Heater" on the second local oscillator although I personally wouldn't use it.
9) Changed the 3.5mm stereo jacks at the rear to a type more easily available, than what I used originally.
10) Added additional through holes under all of the shielding partition areas to tie top copper to bottom better. NOTE: the shielding provision is best carried out using tin-plate due to space restrictions although it should still be possible to fit PCB material. Tin-plate is available from RS Components but is expensive. You only need about 2 sheets and their pack is 10 sheets. I used the 0.4mm sheets. http://australia.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=tinplate+sheet

11) Have added capability to fit Lodestone Pacific formers in the BPF. This is quite a change as the Lodestone formers are larger than Toko formers and also need a 6.4mm hole on the PCB. Toko formers are getting harder to buy and the Lodestones can only be bought in large quantities, requiring a group buy. Amidon have an L43 series which can replace the Toko formers directly and from reports, are as good as the Lodestone parts. Please note I have no direct experience with other than Toko formers (re-wound at home). Amidon formers can be bought on-line at https://www.amidoncorp.com/ and are about US$3 each.
12) I had looked also at changing the FST switches in the BPF to relays but after investigating various relays, their availability and cost, I decided to stay with the FST3125 devices. I always have to consider parts availability for these PCB's and try to use what is reasonably available in quantity around the world, where possible.
13) Combo PCB has provision for a line output transformer. The 1:1 PCB mounting transformer I used is readily available in VK but not it seems, elsewhere. I have no solution to this except that you will need to find something suitable in your own Country, if you elect to add this option.
14) The Combo PCB has three PCB mount 3.5mm stereo jacks (sockets) at the rear. One is for line out as above, one for external speakers and the third for a Morse key. The loudspeaker jack switches off any internal speakers you may fit also.
15) The RS232 connector is a PCB mounted type (DB9) on the rear edge of the PCB. The RS232 "normal/monitor" switch is located there also.
16) Reverse polarity and power on switch. A relay is fitted to the PCB for basic reverse polarity protection and this also allows a front panel ON/OFF switch to be fitted if required. Rating of the relay will determine if the 140W PA can be supplied also, but since the relay is not hot switching high current, the 16A one I used may well be sufficient. This is the same type of relay as used in Picatune. The DC supply input and also to the PA uses automotive type 6.3mm PCB mounting tabs. (As used on the G6ALU 140W PA) These have been arranged so that two cables can be paralleled if needed.

I will be starting a new Web page for this PCB panel soon. It will be at www.carnut.info

This page will be the Constructor's information page with Bill of Materials (BOM) , schematics, PCB overlays, feedback, builders pages etc.

I have spoken to Art Allen, KY1K, who some of you may know supplies component kits for various other Amateur Radio projects, like the N2PK VNA. He is looking at the BOM and is considering doing some kits but that will depend on demand also. I don't know exactly what form this may take, at this stage. It may not even go ahead.

Components however are essentially those used on PICaSTAR as COMBO simply re-packages the same PICaSTAR PCB's into one larger PCB. There are a few additional parts but in the main they are connectors and the like, commonly and cheaply available.
For those looking for the Analog Devices parts, check www.utsource.net Be sure you have exact part numbers !

The components for Trxavrb PCB will be uploaded to a BOM (Bill Of Material) and will be on the above web pages as I get time.

Component lists for the G6ALU PA boards and G4TZR Low Pass Filter, are available on G6ALU's web pages. (the relay hole error on the LPF has been corrected also)

So... The PCB COST

I now have a group buy cost for the Combo PICaSTAR Panel as above, and INCLUDING Steve's 140W Power Amplifier:- ALL COSTS ARE IN AUSTRALIAN DOLLARS !

For non VK's

PCB's COMBO panel and 140W PA's $ 104.90

Postage $ 20.60

Paypal $ 4.39

TOTAL:- $ 129.90


The cost is based on QTY 30 and parcel postage is an estimate from www.auspost.com.au for a parcel in a padded bag or similar.
I have to verify the weight of the PCB's to finalise the postage cost. The Panel will be posted in one piece.

If less than 30 builders do not participate in this group buy I will have to either cancel the order or re-negotiate the quoted price.

If we reach the next milestone of 40, then I will get a quote for that number. The cost will probably drop by $6 or $7.


The PCB's will be sent via airmail in a padded bag and will be uninsured. It is simply too difficult to handle the paperwork for each individual item posted and to fight with the Postal company over any item lost and claiming insurance. In the past, no known panels have ever been lost in shipment outside of Australia so the perceived risk is very low.


As in many hobbies, this has been a labour of love for me over a long period. As explained above, two Combo PICaSTARS have been built but I cannot guarantee the final PCB in any way other than all care has been taken in it's design and I have no control how you choose to assemble and house the PCB. There may be minor glitches in the PCB but I will assist in any way I can to rectify them. You must agree to this to participate.


If you are happy with the disclaimer and the cost above, do NOT pay me yet.
Please advise if you wish to go ahead or cancel your interest.

I do not anticipate another order after this.

To be fair to all, please do this immediately so I can finalise the group buy. And once I call for payments, please do so quickly. There is nothing worse for me than waiting for one or two late payers.

Once numbers are final and payments are made, the PCB order takes about 15 days for delivery to me. The PCB's are made in Australia by the way.


22nd October, 2009

BACK to Combo web page or HOME