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 Post subject: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 7:09 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
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I have a 170 that I've cleaned up nicely and working well, and now a 170A that needs the treatment. Having done that, both will be more or less in the same shape, except for the A has quite a bit of missing cadmium plating on the chassis. But performance wise, is there really any great advantage of the A model over the non-A? One thing that dies irk me to no end is the way the A leaves 2 tubes lit unless you unplug it every time. The reason I ask is one of them will have to go.


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 7:28 pm 
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You can defeat the constant on tubes easily by rewiring T-30 so that its primary is simply in parallel with the main power transformer. Keeping the filament power applied to the HFO and first mixer tubes was done to reduce drift during warm up and Hallicrafters did the same thing with some models.

The other significant A variant differences are it uses a solid state rectifier which will reduce heat buildup and a "system" socket is including for easier integration with a transmitter.

An early non-A version MIGHT have the problematic open leaf capacitors in the first and second IF transformers and if that is the case it would be a reason to keep the A version. The open design will short due to dust buildup leading to carbon tracks, the first symptoms are noise followed by smoking resistors.

Performance wise, the only difference you will notice is some increase in frequency stability from the always on filaments and somewhat reduced power supply heat of the A variant.

Keep the one that you like best (cosmetics, etc.). The A version is a little better but not enough to justify one with lesser cosmetics or other issues. If you don't like the constant on filaments and don't want to move the auxiliary transformer wire then you can use a power strip to turn it on/off unless you are also using the original clock/timer.

Rodger WQ9E


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 9:18 pm 
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Location: Sayreville, NJ 08872
Add to Roger's stuff:
HQ-170A has open lid on top to get at stuff; HQ-170 does not unless someone switched cabinets.
HQ-170 had several factory addenda to try and get the AVC squared away. HQ-170A redesigned parts of that circuitry to "make it better". Mode switch on 170A had separate AM/CW/SSB positions; 170 did not.
From memory, I believe the 170A had more rear panel stuff for various types of connections/accessories/etc. then the 170.

I have the HQ-170A-VHF version for years which overall works extremely well. Since I always shut off all power to my operating position when I'm not there, always on filament wiring was not a concern. I did have a HQ-170 for a short period but was never satisfied with the SSB and CW reception even applying Hammarlund's service addenda. Found the 170 a new home.

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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 10:34 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
How perfectly frustrating. This 170A came to me with the left dial loose on it's shaft. No problem I thought. But noooo..... It seems that page is missing out of the Bama manual. It would have to be step 7 on page 46 of the manual. There AIN'T no p 46. Logically you would position the tuning gang at a certain place and then set the dial by the mark and tighten it down. And the tuning gang on the A is only a 2 section, whereas the regular 170 is a 3 section. So that's no help. Damn.


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 10:44 pm 
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Location: Sayreville, NJ 08872
why I do what I do :mrgreen:

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http://www.classicradiomanuals.com


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 11:13 pm 
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Quite a few of the pieces of vintage gear I have purchased over the years have come with manuals from Pete. There is a reason why his service is so popular because you get complete and very readable documentation.

Rodger WQ9E


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 11:21 pm 
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Joined: Aug Fri 22, 2008 9:42 pm
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Location: Long Island, NY
I bought a HQ-170 when they first appeared and it had drift issues. The mods to the 170A were supposed to resolve those problems. I bought a SX-101A to replace the HQ-170 I returned, which was a more stable receiver.

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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Fri 07, 2019 11:30 pm 
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mandh wrote:
I bought a HQ-170 when they first appeared and it had drift issues. The mods to the 170A were supposed to resolve those problems. I bought a SX-101A to replace the HQ-170 I returned, which was a more stable receiver.


The drift issues I've seen with the HQ-170 series, and many other receivers, most of which were attributed to the 6C4 triode oscillator if one was used. Sometimes it took in-circuit testing of several 6C4's before you got one where drift was minimal after "appropriate" warm-up time which varied from receiver to receiver due to part aging/poor part quality/etc.

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http://www.classicradiomanuals.com


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Sat 08, 2019 2:26 am 
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I wonder if it's the same Pete I used to buy manuals from around the turn of the century. I remember them being good work.


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Sat 08, 2019 5:04 am 
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henry finley wrote:
I wonder if it's the same Pete I used to buy manuals from around the turn of the century. I remember them being good work.

Was previous address 103 W. Main St., Marshville, NC?

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http://www.classicradiomanuals.com


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Sat 08, 2019 5:10 am 
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Joined: Jul Sat 28, 2012 9:32 pm
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Yes. That was my print shop. Long gone though.


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 Post subject: Re: Hammarlund 170 &170A Compared?
PostPosted: Jun Sat 08, 2019 5:40 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
I was able to get the dials into reasonably good position, just out of experience. One of the setscrew holes had been partly stripped, but I was pleased with the new set screws I went out and bought. I'm confident I have a good starting point for alignment down the road. But right now I've got to deal with a lot of destruction to the cadmium plating on the chassis. I wonder how airbrushing with a silver enamel with hardener added would work out. Not to laying on a thick coat, but just for some light color blending where needed. Electronically, getting the radio basically working after 3 months of sitting out in the weather was the easy part.The radio does play. And to think my friend was going to part it out. Absolute heresy.


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