HQ 180A deaf over 15 mhz

[iw5ci]

Under 15 mhz is very sensitive, above is quite deaf (it receive but is definitely with a low sensibility) do you thin is a weak tube?

[WQ9E]

Try a different 6C4 in the HFO position, the HQ-170/180 is very picky about this tube.  The other tube possibility is the 6BE6 used in the first mixer position.

[N8ETQ]

   Perhaps it's just tuned to MSNBC.

/Dan

I know that was bad!

[W8IXY]

About 2 years ago my HQ180A also went kind of deaf on the >15 mHz switch position.  The HF oscillator just stopped when tuning above about 17 mHz.   

I replaced the 6C4 with a NOS tube with a date code from 1945!   Worked perfectly through 10 meters.

Also, the 6BE6 used in the first mixer is inherently a bit noisy.  If you can find some NOS 6BE6's, try swapping a few around for the best noise performance.

The 6BV8 (still working just fine) is still the original one that was in the receiver when I purchased it brand new in 1964.

73

Ted  W8IXY

[iw5ci]

Thanks a lot ! i will give it a try.

[The Slab Bacon]

Hammarlunds, especially the 145-X, 170, and 180 are very particulat about the 6C4 HFO tube. I have had this problem on several occasions.

A N.I.B. tube isn't always the answer. I have had brand new ones that wouldn't oscillate properly, and old looking piss-beat ones that worked perfectly. Usually they will oscillate fine in the lower portions of the bands (cap near full mesh) and squeg, fweep and finally stop oscillating all together an you tune up the band. (unmeshing the cap)

Just because the tube is new doesnt mean it will work properly. I find this to be a
"test-select" situation. Although the NIB older RCA tubes seem to work much more reliably. I had one drive me nuts a few years back!!!

Also be sure to have a good one in there BEFORE even attempting to adjust the oscillator / dial tracking an they will also move around in frequency if they are not oscillating stably.