[Hammarlund] HQ-129-X Serial Numbers

[Carl]

+1 for Ken.

All the 6 band/range position single 455 IF HQ Hammies have both the 2 
highest bands LO on the LOW side.

Most other radios with only 4-5 bands have only the highest band on the low 
side and generally that generally starts around 14-18 mc.

Carl
KM1H


----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
Cc: <Hammarlund at mailman.qth.net>
Sent: Tuesday, August 14, 2012 4:10 PM
Subject: Re: [Hammarlund] HQ-129-X Serial Numbers


> On 14 Aug 2012 at 11:05, Richard Knoppow wrote:
>
>>      Its definitely supposed to be _below_ the signal on the
>> highest band.
>
> Yes. That's what I said.
>
>> I tried it on the next highest band but there
>> is not enough range in the adjustments to do it and
>> calibration is reasonable so I think its supposed to be
>> below there two.
>
> Yes. Here is what I just read yesterday:
>
> "The local oscillator operates 455 Kc lower than the incoming signal on 
> the 18-31 mc and 10-
> 18 mc band, but 455 kc higher than the incoming signal on all the rest of 
> the bands."
>
>> On the others its supposed to be higher.
>> If its supposed to be higher on the 10-18 mhz band then
>> something is wrong.
>
> No, It is supposed to be lower there. That is correct, and is proven by 
> the fact that 20 meter
> calibration is quite good.
>
>> Curiously, the band spread calibration
>> on 20 meters is quite good, its the two lower bands where
>> its off.
>
> Yes. That means that the upper bands, 10-18 and 18-31 mHz bands, are 
> correct, but your
> lower bands are incorrect.
>
>> From the symptoms it looks like the overall
>> capacitance is too _low_ there causing the band spread cap
>> to have to move more than it should.
>
> That, alone, would indicate to me that the LO is BELOW the incoming signal 
> frequency, and
> it SHOULD be ABOVE the incoming frequency. Higher frequencies require LESS
> capacitance-change to cover more frequency range. The very fact that you 
> say it appears to
> not have enough capacitance indicates to me that the LO is on the wrong 
> side of the
> incoming signal.
>
>> Too low would suggest
>> that if the LO were above the signal it should be moved
>> below it but its already below it.
>
> No. That is backwards. If there isn't enough capacitance, that would 
> indicate the LO must be
> ABOVE the signal frequency, but isn't, since higher frequencies require 
> less capacitance. If
> the LO is below the signal frequency, then that is backwards.
>
>>  The total capacitance is
>> the combination of the main tuning cap and the trimmer cap.
>
> Yes.
>
>> Obviously it must be greater to move the LO lower.
>
> Yes, but that is only part of the point: the total capacitance required 
> for resonance at HIGHER
> frequencies is LESS than that required for resonance at LOWER frequencies. 
> Therefore, if
> you don't have enough capacitance to resonate the circuit when the LO is 
> BELOW the signal
> frequency, then the LO is on the wrong (LOW) side of the signal frequency, 
> and must be
> moved above.
>
>>  If I
>> changed the LO to being above the signal it seems to me it
>> would make this condition worse not better.
>
> No. The opposite would be the case. Higher frequencies require LESS 
> capacitance for the
> same "Q" and for resonance.
>
> Possibly I'm not making myself clear. I insist that the LO is on the wrong 
> side of the signal
> frequency for 80 and 40. It MUST be ABOVE the signal frequency, and yours 
> is OBVIOUSLY
> below it.
>
>> In any case,
>> when I try that the core on the inductor want's to be all
>> the way out and still won't quite make it. When below the
>> signal the inductor is in a reasonable place.
>
> That simply indicates to me that the whole thing is out of whack. What I 
> would do is 1) center
> the core of the inductor, 2) adjust the CAPACITANCES (reduce them) at the 
> high end of the
> band(s) to make certain the LO is ABOVE the incoming signal frequency and 
> aligned, and 3)
> THEN tweak the core of the inductor at the low end of the band to get 
> things in total
> alignment there, and lastly 4) go back and forth to finalize the alignment 
> at the ends.
>
> A thought just occurred to me: does the manual suggest that you set the 
> bandspread
> capacitor at a different setting for the lower bands then for the higher 
> (10 MHz and above)
> bands when doing the alignment?
>
>>      I've inspected all the capacitor sections carefully and
>> none appears to be decentered and there are no bent plates.
>
> That fact that the receiver works fine above 10 MHz would indicate that 
> there is absolutely
> nothing wrong with the tuning capacitor.
>
>> This may be something obvious that I am missing.
>
> See above. ;-)
>
> Ken W7EKB
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