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Hi all,
Last week I built the QDX Hi feq. Version? 5 for 20m, 17m, 15m, 12m, 10m. Blue/ yellow toroids. At 12V.
On all frequencies I get more than 4w output, except 15m/ 21Mhz. on a? 50 Ohm dummy load.
There I got 0,2w output? and BS170 are getting
:very hot.
I reworked soldering and checked all components arround L3 and L8.
With Putty I found the only difference with for example the 17M is the use of the BPF.?
Which components/connections should I control? to make 15m also working? ?
HELP WANTED!

Btw: On 10m I worked on 10 m FT8 USA stations with my short Endfed antenna!!!
So the system works.
Rob PA0RBL

Rob,
If L7 is not broken (47uH), then also check Q4 BSS123.
--
Gyula HA3HZ

ps.: and D2 and D5 polarity is installed correctly?
--
Gyula HA3HZ

Rob,

To confirm, you are getting more than 4 watts out on 17 meters.? If that is the case, and you are sure of the proper number of turns on L3 and L8, I would suggest verifying the capacitors and that you put the toroids in the correct location.? 15 and 17 meters share the same low pass filter.? A lower power on 15 vs 17 meters would indicate a low corner frequency for the filter.? Try squeezing the turns closer together on L3 and see if you can get 15-meter power to increase.

73
Evan
AC9TU

A good place to start is to look at the RX RF sweep for 17/15m if the same facility exists in QDX (I'm only familiar with QMX). Changing LPF parameters in the dark and get them right is very hard.

Also, good idea is to make sure L3 and L8 are perpendicular to each other and have decent distance between them.

Hi all,
Thanks for the reactions so:
I tested L7 with my multimeter (in circuit) and gives 0 Ohms.
Polarity D2 an D5 (also tested in circuit) and OK.
Number of turns L3 an L8 are 12 windings so also OK
Capacitors 2x checked also OK

I think if 17m works than Q4 must be ok too for 15m?

I will make an screenshot for 17m and 15 m? RF filter sweep and post them after this message.
At this moment I don't know where to look next.
Other ideas??
73's de Rob? PA0RBL

My screenshots

As Evan recommended, try pulling the threads of L3 closer together and check the change.
It may be necessary to shift the threads of the coil in one direction or another on the other coil.
Whatever you change, measure the output to see what it changed.
During the production of of the rings, a possible deviation can be corrected with the capacitance between the threads.
Another option is to specify the uH value and set the desired value by measuring before installation.
--
Gyula HA3HZ

Hi,
to test if the too low LPF cut-off frequency is the reason you could try using the 10m LPF on the 15m band and see the possible change in the output power.
--
73 Bojan S53DZ

Hi,
After new power mesurements I found out that both 15m and 17m are now low but 17m some higer than 15m .?Using the 10m LPF changed in Band configuration to 2 with Putty everything changed. Now power looks OK. So it looks like Gyula could be right with Q4 not working.. Someone has a spare one??
Thanks for co-thinking!
73's de Rob PA0RBL

Hi all,
After new experiments (and blowing two BS170 due to bad SWR bij no dummy load, Hi) I found out that? the LPF switch is working.
But changing the?15m LPF in Band configuration to 2?(the 10m LPF) and keeping the 17m?Band configuration to 1 I got after squizing etc. the next power outputs:
20m 4W
17m 4W
15m 2,2W
12m 2,5W
11m 2,2W
10m 2W

What component in the LPF could? be the problem on the 15/17m LPF.
Windings are OK and C's are OK.
Rob PA0RBL