NB There is an updated schematic uploaded June 28th 2009.Well, I've completed a breadboarded version of the SixBox, an ultra-simple 6m QRP AM transceiver which I've had in my mind for some time. As it stands, without a linear, it produces around 50mW AM (200mW peak) from the 2N3904 series modulated PA. It is not in a box, just a rats nest on a piece of copper clad board, but it works. The receiver is a super-regen using MPF102s with an isolating RF amplifier loosely coupled to the super-regen detector. A varicap diode (to be added) is used to tune across the band. The TX consists of a 25MHz xtal, a x2 multiplier and PA both of which are series modulated. Ubiquitous 2N3904 transistors are used throughout apart from the super-regen stages.
Click on the schematic to see what it consists of. It would readily scale for 4m although the T37-6 toroids would be a bit marginal this high. I was surprised how well they worked at 50MHz.
I should be DELIGHTED if someone wanted to develop this circuit further and maybe produce a small PCB and case.
On reflection, I think the DSB version of this would be a better bet. Much of the TX line-up can be re-used for this but I would use a DC receiver. 200mW pep of DSB (equivalent to 100mW SSB) would be quite a useful power. My next project will be to complete the DSB version, either for 6m or 10m.
Thanks for your efforts Roger. I will make a version over the coming months (In the middle of a QTH move at present). Would it be possible for you to develop some notes on the windings required for 4M operation? I presume the TX is simply changed to 1/2 the working tx frequency for 70.26MHz. Not an expert in this area.
ReplyDeleteThanks.
73, Dave GW8JGO
Hello Roger,
ReplyDeleteThis is an interesting circuit; I'm going to build a receiver. Is C6 the gimmick cap or C10?
Is there enough regeneration to receive CW signals?
72
Goody
K3NG
Goody,
ReplyDeleteWhen renumbering the parts it screwed up.It is the cap between the 2 RX coils . Just get a few mm of 32swg or similar thin enamelled wire and twist together - makes a simple small cap. Too much coupling will kill the super-regen stage oscillation.
Good deal. Have you tried using it to receive CW? A local friend here just discovered 6m and he's looking for a new ham project to get local guys on 6m with a minimal investment.
ReplyDeleteAlso, I'm wondering if one could pull a 25.000 MHz crystal far enough to get to 50.135 MHz (or more) with the doubler?
A super-regen RX is no good for SSB and CW. You'd need to turn back the regeneration so it behaves as a normal regen RX with the detector stage just into oscillation. For SSB and CW a direct conversion RX is a better approach. This is what I am doing next as part of my DSB project.
ReplyDeleteA 25MHz xtal should pull around 1kHz/MHz so at 50MHz a 50kHz VXO range should be achievable. With two parallel xtals the range would be greater.
Dear Roger G3XBM,
ReplyDeleteMay I introduce your SixBox transceiver note in 2009 Japanese Arateur Radio Festivals ? Now I am preparing attractive article for 6m AM enthusiasts. I will translate it into Japanese.
JL1KRA Junichi Nakajima
Junichi San,
ReplyDeleteThank you for your interest in the SixBox. I am very happy for you to translate this into Japanese and to share the idea with hams in Japan.
73s
Roger
Dear Roger-san, G3XBM
ReplyDeleteThank you your prompt reply and
permission of Japanese translation.
The Japanese Ham Festival will be held in the end of August. I am sure many Japaese
builders will be interested in the SixBox. Since all parts you used in the transceiver are easy to obtain.
I will let you know the result and
of course I will send you the translated version later.
Sincerely
Junichi Nakajima JL1KRA
Hello Roger,
ReplyDeleteHaving just read (In Sprat 140) your excellent articles on WSPR and The SixBox I would encourage you to continue with the 10/6 metre DSB version (with a pcb layout). That would make a marvellous base for WSPR experimentation! (Published in a future Sprat?) - and allow 'simple' repeatable PCB construction for us less gifted types!
73, Richard G8ITB
Hi Richard,
ReplyDeleteYes I intend to get on with the DSB version very soon now. I've been distracted, in a nice way, by 500kHz WSPR recently , but I do want to get a neat little 10m DSB transceiver done within the coming months.
73s
Roger
hey mr roger will this amtransceiver will work in the philippines, we have a school project of amtransceiver i hope this will work
ReplyDeletewill it work in philippines?
ReplyDelete