Oh, I forgot to mention, that is with 24V on the PA.
My plan is to get the new board up and running and then I can compare the voltages etc. between the two and try to figure it out. And no, I don't mind a bit, I have a lot to learn.
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On 6/20/2017 7:51 AM, Raj vu2zap wrote:
Jonathan, I would consider 5W within limits.
Let me tell you a condensed story!
My Ft757Mk2 was on 10M CW. Nice pileup. Then I heard a bad tone so I gave him a T5 and he did the same. I shut down.
I opened the rig and probed and all was fine. The rig did the same after some time.
I finally realized that the PLL lost lock and was creating noise hunting for a lock.
I found the signal in the feedback loop was low when board was hot.
I figured that the loop gain was low. I just swapped some 2SC535 as I remember from other parts of the rig and
Problem solved.
Sometimes a combination of semiconductor parts results in such situations! If everything works then we don't learn anything new!
Cheers
Raj
At 20/06/2017, you wrote:
Raj,
Thanks. Low mic gain might be it, but I thought you should get 5W out of the simple electret mic included?
And the issue is that I have to crank R136 fully over to get the 5 watts. I will short out R131 and see what happens.
JOnathan
On 6/19/2017 10:43 PM, Raj vu2zap wrote:
Could be due to any or many of the following reasons:
1: Low audio drive - very likely (I use an amped Motorola mic and it goes up to 10W)
2: Low VFO or BFO levels
3: BFO frequency may need tweaking to suit the filter or your voice.
4: Low BiDi amp stage gain - unlikely
5: Low gain in final RF amp stages - short out R131 and see
Considering you get 5W it is not really low as you think!
Cheers
Raj
At 19/06/2017, you wrote:
HI All,
My original BITX never "aligned" correctly. In order to get the 1 amp current draw when hallooo'ing into the mic I had to crank R136 all the way. In that way I could get 5 watts out but only if running higher PA voltages.
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Thanks!
Jonathan - KK6RPX
