[Hammarlund] HQ-180A 60 KHz IF Problem - Suggestions?

[Dan Martin]


> 
> So, please don’t take any of this to say that digging out the proper alignment
> procedure is unimportant. It is *very* important. It can make the difference 
> between utter junk and a functional result.

So is this a good time to bring up the old debate for the single-conversion Hammarlunds of whether to align the IF’s:

1. By ear?
2. Strictly to peak at a fixed 455 kHz?
3. To the prevailing crystal frequency and use a spectrum analyzer?

Just kicking the hornet’s nest. 🙂

Dan
WB4GRA

Sent from my iPhone

> On Feb 2, 2022, at 5:59 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
> 
> Hi
> 
> A story ( sorry for heading off topic ….):
> 
> Back in the 1970’s I worked for Motorola. I was out on the production line
> one day and happened across a gal doing up Permakay filters. In that era
> this was an unusual thing to be doing. They went into repair parts inventory.
> 
> Watching her do this / peak that / dip that / peak something else was an 
> absolutely amazing thing. Without *knowing* just exactly what you needed 
> to do, the result would be utter trash. The speed she did it at …. wow !!!
> 
> If you dig into all the math of how complicated filters work there are good
> reasons for it being a bit nuts. Some filters are only functional if you align 
> them with a network analyzer. Fortunately that is not those filter are not 
> typically what you find in an HF radio (at least not coil / capacitor versions). 
> 
> Bob
> 
>> On Feb 2, 2022, at 5:24 PM, Steven Reed <reedsteve59 at gmail.com> wrote:
>> Bob,  it's not what I wanted to hear, but in all honesty I believe you're over the target.  In thinking about this some more -- while on one hand it is very rare for multiple components to fail, it's probably not so rare for multiple components to (as you've pointed out) drift out of spec due to age and environmental issues.  I think the only rational option at this point is to recap everything in that IF section, including the switch.  I've got a parts HQ-180A as well, in case any of the IF coils have issues.  I'll probably do the switch first because the work is far less invasive, but if that doesn't fix the problem then the transformers come out.
>> Steve.
>> On 2/2/22, 2:55 PM, "Bob kb8tq" <kb8tq at n1k.org> wrote:
>>  Hi
>>  Regardless of how you do an alignment (which *can* be tricky. Loading
>>  resistors / shorting this or that can be involved …) The IF response should
>>  peak in the right vicinity. There should not be some single individual component
>>  that can fail and move all the transformers 20% low. That’s just not how
>>  this stuff works.
>>  Bob
>>> On Feb 2, 2022, at 1:57 PM, Steven Reed <reedsteve59 at gmail.