[Hammarlund] HQ-170 Query

[Kim Elmore]

I'll look more carefully where you suggest for a S/N, but I agree that 
it appears to be the AGC that was fiddled with across all the schematics 
I've seen. I won't simply replace the resistor and hope for the best: 
something caused it to burn up and that won't have fixed itself on its 
own. I need to find what set it off in the first place.

73,

Kim N5OP

On 1/27/2026 9:47 PM, manualman at juno.com wrote:
> The Hammarlund HQ-170 was in production from 1958 to 1962.
> All 4 issues of the schematic show the same value of the resistor, 27K 2
> watt.
> The only thing major to the HQ-170 later in its life cycle was in the AGC
> circuitry which, I believe, they tried twice. They didn't get close until
> they introduced the HQ-170A.
> Most likely Issue 1 or 2 would be the logical choice for your receiver.
> Replacing the resistor isn't enough; you need to find out why it burnt
> up.
>
> Serial number generally can be found looking at the rear of the chassis
> apron lower left side. If it's still visible, it can be stamped or
> embossed. A magnifying glass can help.
>
> Pete, wa2cwa
>
>
> On Tue, 27 Jan 2026 16:56:38 -0600 Kim Elmore<cw_de_n5op at sbcglobal.net>
> writes:
>> I have an HQ-170 purchased new by my dad (W5JHJ SK 2007) in 1949. It
>> has
>> developed a problem, characterized by an incinerated resistor on a
>> line
>> coming off of pin 6 of V5 (third mixer). I no longer have the
>> original
>> manual and I cannot find a serial number ion it anywhere. I have
>> seen
>> (but no longer have) the original purchase receipt for it, dated May
>>
>> 1959. I've determined that there are at least four different
>> schematics
>> for the receiver for various production upgrades. I'd like to ensure
>> I'm
>> looking at the right schematic, but without a serial number I'm a
>> bit in
>> the dark. It's in beautiful condition since he, and later I, took
>> great
>> care of it.
>>
>> I'm not as familiar with the HQ-170 as I am with his WRL Globe
>> Champion
>> 350, also purchased new by him in June 1959, and slo in superb
>> condition. I've worked on the Champ a fair bit (now needing a LV
>> transformer replacement) but aside for alignment and preventive
>> maintenance/electrolytic capacitor replacements in the HQ-170, this
>> is
>> the first time I've had to get into it. How do I know which
>> schematic is
>> the correct one to use?
>>
>> 73,
>>
>> Kim Elmore N5OP
>>
>> P.S.: The HQ-170 is currently off of the bench so that I can address
>> the
>> Champ's LV transformer replacement.
-- 
Kim Elmore, Ph

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, UAS, N5OP, 2nd Class Radiotelegraph, GROL)

/“Listen, it's too big a world to be in competition with everybody else. 
The only guy I have to get better than is who I am right now.” – Col. 
Sherman T. Potter, 4077 M.A.S.H./