75A


Robert
 

On May 15, 2020, at 7:15 PM, n5ib_2 <n5ib@juno.com> wrote:

Truth, Justice, and white screens on green masks forever!!

Amen!
Robert
K5TD


Timothy East
 

Thank you very much.  I will double and triple check my orientation and try to correct the orientation, if needed.  But, I have already lost a solder pad and am not sure how many more desoldering/resoldering attempts can be made on this component.

Tim


From: main@4SQRP.groups.io <main@4SQRP.groups.io> on behalf of n5ib_2 <n5ib@...>
Sent: Friday, May 15, 2020 7:15 PM
To: main@4SQRP.groups.io <main@4SQRP.groups.io>
Subject: Re: [4SQRP] 75A
 
This is a good excuse to do a little engineer/detective work involving the schematic and the data sheet.

The schematic shows that the Source of Q2 is to be connected to the ungrounded side of R8.

The data sheet (see message # 22052) has a pictorial that identifies the Drain, Gate, and Source leads unambiguously.

Close examination of the PC board shows a trace, on the top side of the board, hiding under that black solder mask, from R8 to one of the pads of Q2. That pad must be therefore be intended for the Source lead, and all the rest will fall into place.

Of the two flatted sides of Q2, the wider one must face towards the blue resonators - as shown in a couple of posted pictures.

Tongue-in-cheek aside to Dave, NM0S ...   When you get to the Pearly Gates, Dave, and I have no doubt you've earned your way in, St Peter is going to look in his QRP logbook and exclaim, "Welcome NM0S, but... why, oh why, oh why the fascination with black solder masks?  We usually send those to the repair techs in that 'other place' as their pennance"     LOL

Truth, Justice, and white screens on green masks forever!!

Jim, N5IB




ohwenzelph
 

Re Q2: Is this correct?


Donald <donwestpwl@...>
 

I worked for over 30 years as an electronics technician, and that's the first three-legged transistor I've seen with lettering on the back side of the device! I can see where this situation could be confusing. In my opinion, you have Q2 installed correctly. When you look at transistor datasheets, the manufacturer shows the pinout according to the shape of the device, not the lettering.

On 5/18/2020 9:29 AM, ohwenzelph via groups.io wrote:
Re Q2: Is this correct?


nm0s_qrp
 

Yes, correct!


WA4LLR <wa4llr@...>
 

Another 75A question. Just built one. The xmit carrier output is 1 watt. The RX sensitivity is approx 15 microvolts and the RX frequency is offset approx. 66khz from the xmit frequency. What did I do wrong? Thanks for any input.
Dave



Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------
From: "ohwenzelph via groups.io" <Ohwenzelph@...>
Date: 5/18/20 10:29 AM (GMT-05:00)
To: main@4sqrp.groups.io
Subject: Re: [4SQRP] 75A

Re Q2: Is this correct?




nm0s_qrp
 

How did you determine the frequency offset?