Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
QDX-M for 6M
|
Hi all,
I have now completed my third QDX which is the QDX-M version which I have configured for 6m. After much playing with the inductors and capacitors I am getting an RF output of 1.9W with PSU at 0.54A (Receive 0.170A) into a dummy load. I am using the values as posted by a few others on the forum but cannot seem to achieve the 2-3W that others have mentioned. My setup:-
C20 & C7 63pf C11 8pf C14 126pf L4 10t on T37-17 158nH L10 11t on T37-17 180nH L12 10t on T50-6 600nH C28 22pf Built for 9V with WTST transformer. I have expanded and contracted the windings of L4 &L10 to get the best output. The PUTTY report for RF sweep shows peak frequency spot on 50.293MHz. Everything seems to be working as it should. Just low RF output.
I'm measuring RF output on my Siglent SDS1102CML+ as 27.8v p-p and converting. I would welcome any advice from those who have already successfully built the 6m version before I do any damage to the pcb!
73 Chris G0IMX
?
|
|
Hi All,
Just an update to those with working 6m QDX-M's. I watched a UTube video of Hans tuning LPF's and realised that my 6m LPFs were both expanded across the toroid ring for best rf output meaning that I should try to take off one more turn from L4 and L10.
I now have 3.84W out into my dummy load. I reckon that's probably as good as it gets! So my only change is L4 9turns and L10 10turns on T37-17s for 3.84W.
Nothing much happening on the magic band today and I need a base station antenna for 6m as my present antenna is a SE HF-360 XP 160m-6m which doesn't seem to be very sensitive on 6m. 73 Chris G0IMX
?
|
|
Hi Nate thanks for the reply. After I posted my last settings for 6m I had a problem after fitting the pcb into a custom case. I lost nearly all rf power out and decided that this must be a dry joint on the LPF section so reflowed most of the caps and toroids ?to see if that helped. It brought some power back but only 2.1W. Finally after much squeezing and relaxing the windings of L4 and L10 without success I looked at my piggy-backed caps with non standard values. C14 had a short to earth and now after repair I have an output of 3.16W but it's very difficult to get the right spacing of windings for best output. Also might look at L12 again as I used the group recommended T50-6 with 10t - the turns are squeezed onto half of the toroid for best peak of the Putty rf filter test. As for contacts - no signals received - and it seems the band is very quiet even with a local 6m amateur operating only 20m away. I'm a qrp operator and the most powerful equipment I have is a 10w linear amp! And I don't expect to get many contacts until I get a better antenna. Good luck with your build.. Let me know if you need any more details of my build. 73 Chris G0IMX |
|
On Mon, Jan 27, 2025 at 03:47 PM, G0IMX wrote:
Chris G0IMX Hi Chris! It's not the 6 meter season now, although this band was already opened in January. On QDX last year in a couple of months I conducted more than 100 QSO with 32 countries with a power of a little more than 2 watts with a half-wave vertical antenna. So everything is ahead.
--
73, Oleh, UY2ZA |
|
You should be getting desense from that distance HI
toggle quoted message
Show quoted text
On 27 Jan 2025 at 6:47, G0IMX via groups.io wrote:
the band is very quiet even with a local 6m amateur operating only 20m away. |
|
Thanks for the feedback, Chris!
?
On Mon, Jan 27, 2025 at 08:47 AM, G0IMX wrote:
Also might look at L12 again as I used the group recommended T50-6 with 10t - the turns are squeezed onto half of the toroid for best peak of the Putty rf filter test. ?
Does that mean it was peaking too low, otherwise? Wondering if 9 turns, or a smaller capacitor value should be considered for the BPF....
?
-Nate?
N8BTR |
Mike
to navigate to use esc to dismiss