I've posted this over at ARF but thought maybe those here who don't frequent that form might also have some helpful input for me.

Yesterday Gary a fellow forum member and I were working on his standard AA5 Admiral It is a small table top with a loop antenna.
He asked me to help him re-align it because he wasn't sure if he had been doing it properly. He noticed that the sensitivity was either all at the low end of the band or at the high end but not even enough to cover the whole BC range properly.

I re-aligned the (slug tuned IF 455kc) transformers and then followed the standard, straight forward instructions carefully.
Set the gen and dial pointer to 1600 and adj the osc trimmer for max.
Then Set the gen and dial pointer to 1400 and adj the Antenna/Tuner trimmer for max.

After doing this several time to be a accurate as possible we found that the upper band was nice and sensitive well on down to about 800kc when we could begin to notice that the stations down there were noticeably weaker.

If we tuned to a low end station and we tweaked the Ant/tuner trimmer to max that station... then there would be NO sensitivity at all on the upper end.

There doesn't seem to be a happy compromise anywhere!

What do you think might be the reason?
Is it just a cheap crummy design...??

Is it caused by the Antenna loop coil and Tuner combination having too high of a "Q" causing the frequency range to bee too narrow?

Any ideas how to improve the situation?

:I've posted this over at ARF but thought maybe those here who don't frequent that form might also have some helpful input for me.
:
:Yesterday Gary a fellow forum member and I were working on his standard AA5 Admiral It is a small table top with a loop antenna.
:He asked me to help him re-align it because he wasn't sure if he had been doing it properly. He noticed that the sensitivity was either all at the low end of the band or at the high end but not even enough to cover the whole BC range properly.
:
:I re-aligned the (slug tuned IF 455kc) transformers and then followed the standard, straight forward instructions carefully.
:Set the gen and dial pointer to 1600 and adj the osc trimmer for max.
:Then Set the gen and dial pointer to 1400 and adj the Antenna/Tuner trimmer for max.
:
:After doing this several time to be a accurate as possible we found that the upper band was nice and sensitive well on down to about 800kc when we could begin to notice that the stations down there were noticeably weaker.
:
:If we tuned to a low end station and we tweaked the Ant/tuner trimmer to max that station... then there would be NO sensitivity at all on the upper end.
:
:There doesn't seem to be a happy compromise anywhere!
:
:What do you think might be the reason?
:Is it just a cheap crummy design...??
:
:Is it caused by the Antenna loop coil and Tuner combination having too high of a "Q" causing the frequency range to bee too narrow?
:
:Any ideas how to improve the situation?
:
Peter: My first thought was a poorly operating or "flat" oscillator tube. Sometimes they respond well on some frequencies, but not others. Don't know which model of Admiral AA5 you are working on but it probably uses a detector/oscillator combo tube. Have you tried swapping that tube? That's a problem that won't show up on a testor. If you don't have another tube to swap, you might try increasing the plate current by using a slightly lower value cathode bias resistor and see if it helps. Changing the tube is a better bet. Something to consider.
Steve

:Peter: My first thought was a poorly operating or "flat" oscillator tube. Sometimes they respond well on some frequencies, but not others. Don't know which model of Admiral AA5 you are working on but it probably uses a detector/oscillator combo tube. Have you tried swapping that tube? That's a problem that won't show up on a testor. If you don't have another tube to swap, you might try increasing the plate current by using a slightly lower value cathode bias resistor and see if it helps. Changing the tube is a better bet. Something to consider.
:Steve

Thanks Steve:
Yes the mixer is a 12sa7 and swapped that with NOS... no performance increase.
Over at ARF it was suggested that I try a turn or two more or less on the loop ant. Or to bend the plates as needed on the RF tuner cap. I was bending the plates outward but that didn't seem to help so I returned them to straight.
When Gary comes back w/the radio I'll try a few things and re-post.