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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.

I got a second board and was playing with it yesterday. I wanted to see
if it behaved differently. So I hooked up the PWR, PA PWR and a mic. I
get about 127mA at idle but no increase when I halloo. Does the VFO need
to be connected? I'm guessing so but just thought I'd ask. That takes a
little more doing and I was just curious.

Thanks!

Jonathan - KK6RPX

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.

I got a second board and was playing with it yesterday. I wanted to see if it behaved differently. So I hooked up the PWR, PA PWR and a mic. I get about 127mA at idle but no increase when I halloo. Does the VFO need to be connected? I'm guessing so but just thought I'd ask. That takes a little more doing and I was just curious.

Thanks!

Jonathan - KK6RPX

No VFO - No output!

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.

I got a second board and was playing with it yesterday. I wanted to see if it behaved differently. So I hooked up the PWR, PA PWR and a mic. I get about 127mA at idle but no increase when I halloo. Does the VFO need to be connected? I'm guessing so but just thought I'd ask. That takes a little more doing and I was just curious.

Thanks!

Jonathan - KK6RPX

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.

xxx snip xxx

Thanks!

Jonathan - KK6RPX

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.

xxx snip xxx

Thanks!

Jonathan - KK6RPX

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.

xxx snip xxx

Thanks!

Jonathan - KK6RPX

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.

xxx snip xxx

Thanks!

Jonathan - KK6RPX