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QMX - sockets for BS170s

 

My QMX kit is somewhere between Turkey and the UK so I'm getting prepared...? Has anyone tried or thought it necessary to fit sockets for the BS170s?? Is there space on the board?? It seems to me from some of the photos that one of the toroids might be too close to the pads to fit a socket for one BS170 at least.? Is there also a possible headroom issue?

Grateful for thoughts and experience.

Chris? G4CWS
 

After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?
 

Aha, I knew I'd seen a photo with pin headers under the BS170's recently - check out the picture of the heatsinking on message /g/QRPLabs/message/108109
Might want to ask Cliff, AE5ZA how that is working out ;-)

Graham, M7GRW


On Wed, 30 Aug 2023 at 11:40, Jerry <Jerryh47@...> wrote:
After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?

 

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The sockets work out great on the QDX. I'm about to try them on a QMX so can't say how that works. Space may be tight.

73,
Cliff, AE5ZA



On Aug 30, 2023, at 05:54, Graham Whaley <graham.whaley@...> wrote:

Aha, I knew I'd seen a photo with pin headers under the BS170's recently - check out the picture of the heatsinking on message /g/QRPLabs/message/108109
Might want to ask Cliff, AE5ZA how that is working out ;-)

Graham, M7GRW

On Wed, 30 Aug 2023 at 11:40, Jerry <Jerryh47@...> wrote:
After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?



 

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?I use two rows of 6 machine pin sockets on all my QDX and QMX and 4 pairs for the BPF caps.?

See attached HB QMX prototype.?

73

Ross

On 30 Aug 2023, at 11:51, Cliff <ae5zaham@...> wrote:

?The sockets work out great on the QDX. I'm about to try them on a QMX so can't say how that works. Space may be tight.

73,
Cliff, AE5ZA



On Aug 30, 2023, at 05:54, Graham Whaley <graham.whaley@...> wrote:

Aha, I knew I'd seen a photo with pin headers under the BS170's recently - check out the picture of the heatsinking on message /g/QRPLabs/message/108109
Might want to ask Cliff, AE5ZA how that is working out ;-)

Graham, M7GRW

On Wed, 30 Aug 2023 at 11:40, Jerry <Jerryh47@...> wrote:
After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?



 

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So I think the discussion about pin headers for the PA transistors is adventurous. The most important point with all devices QCX, QDX and now QMX is absolutely the use of a tuner. The antenna needs to be adjusted. This has now been cleverly solved with the QDX with the SWR bridge. The QMX will not work without an adapted antenna.

Of course, if you do WSPR with 12V or even 13.8V with the QCX or QDX, you damage the device and yourself.

?

Yesterday I did FT8 with the QMX for about an hour, with 12V. You could no longer touch the device because it was too hot. It didn't do him any harm. So use thermal paste. Then the PA transistors have a low thermal resistance and everything is chic.

?

73 Reinhard DL3AS

?

Von: [email protected] [mailto:[email protected]] Im Auftrag von Cliff
Gesendet: Mittwoch, 30. August 2023 13:52
An: [email protected]
Betreff: Re: [QRPLabs] QMX - sockets for BS170s

?

The sockets work out great on the QDX. I'm about to try them on a QMX so can't say how that works. Space may be tight.

?

73,

Cliff, AE5ZA

?



On Aug 30, 2023, at 05:54, Graham Whaley <graham.whaley@...> wrote:

?

Aha, I knew I'd seen a photo with pin headers under the BS170's recently - check out the picture of the heatsinking on message /g/QRPLabs/message/108109

Might want to ask Cliff, AE5ZA how that is working out ;-)

?

Graham, M7GRW

?

On Wed, 30 Aug 2023 at 11:40, Jerry <Jerryh47@...> wrote:

After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?

?

?

?
 

Thank you all for your helpful input.??
Cliff - I'd be interested to hear how you get on, if you are inclined to let us know.
73
Chris? G4CWS
 

On Thu, Aug 31, 2023 at 12:52 AM, Reinhard Gr?nz wrote:
The QMX will not work without an adapted antenna.
How does it work with a resonant antenna that requires no tuner such as a dipole or K6ARK End Fed???
?
--
Compton
VK2HRX
Sydney, Australia
 

Looking for some pictures of BS170s set up with sockets. Maybe I'm missing something, but I don't see any in the posts above??
I'm trying to envision what sockets I need to order for my QDX kit (to be delivered today) and how they'd fit with the PAs still against the PCB??
 

0.1-inch turned pin IC sockets would probably be suitable.?

The sockets are for people who fear they will burn out a lot of BS170s and probably want to make them easier to replace.?

Paradoxically they probably make it more probable that you will burn them out, due to:

1. The wires are a main source of heat transfer out of the transistor and the sockets slow that down, so the transistors will probably run hotter.?

2. The sockets add a little parasitic inductance because the leads must be a little longer now, which probably isn't normally desirable.

3. The sockets create a probability of a non-connecting wire; if that happens on one of the BS170s in a pair, then the other will probably be overloaded due to taking all the load and burn-out will be very much more probable.

I personally don't use sockets or recommend them. If you take care of your transceiver with normal precautions such as not using more than the recommended supply voltage and taking care of reasonably well matched loads, then you probably won't burn out any BS170s anyway. I had my QMX putting out 5W on 11m today on JS8Call, 27.245 MHz CB, and several long overs at 83% duty cycle lasting 3 or 4 minutes, and as usual no hint of problems; my antenna SWR is a little sub-optimal right now due to the antenna lying on top of my metal framed roof; and of course 11m is near the top end of the range and PA efficiency decreases proportionate to frequency increase. No issues. As usual... Just my opinion.?

73 Hans G0UPL


On Mon, Oct 16, 2023, 7:22 PM <natereik@...> wrote:
Looking for some pictures of BS170s set up with sockets. Maybe I'm missing something, but I don't see any in the posts above??
I'm trying to envision what sockets I need to order for my QDX kit (to be delivered today) and how they'd fit with the PAs still against the PCB??

 

Well, figured I'd stop back and say this: I've since got over 130 QSOs on 20m FT8, several WSPR transmissions and a JS8Call QSO... and no smoke or burned BS170s yet! I built my low-band QDX for 9V with the WTST, and run it at 7.5-8.9V depending. I took Hans' advice and did NOT set mine up with sockets, paste, or anything fancy for heat sinking.?
This is into a 20m wire dipole tuned to length with my NanoVNA.?

So thanks for weighing in on this Hans, I appreciate it and will soon be ordering a High band version as well as an amplifier for future use!?

-Nate?
Now N8BTR
 

A long while ago fear that the ‘new transistors’ would prove fragile led to them being fitted into sockets in a lot of newly designed complex systems and test equipment (hey it worked for valves)?

This resulted in unreliable equipment and a standing order to the repairs group to jiggle all the transistors until the fault often cleared without further action.?


The transistor sockets soon disappeared from production and reliability improved markedly?

if the BS170s ever do need replacement you’re going to have to remove and replace them all. ?Use very fine wire cutters to snip the leads then pull the leads of each transistor out one by one with tweezers. ?It’s quite simple?
aa0jr Jakob
 

On Thu, Aug 31, 2023, at 02:03 AM, Compton wrote: How does it work with a resonant antenna that requires no tuner such as a dipole or K6ARK End Fed???

K6ARK End Fed or any other antenna which is tuned to your desired frequency, including the unun or balun typically have a resulting SWR better than 1:2. So the reflected energy from tha antenna system is minimal. You can connect them to the QDX/QMX with no problems. I use a homemade 40 meter EFHW for 40, 20 and 15 meter with a homemade 1:49 unun on my POTA activations. After installing it, I check the SWR with a NanoVNA to be sure that my wireing is OK. That is all. 73 de Jakob, aa0jr

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