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 Post subject: HP 608D-worth getting/fixing up for shortwave testing use?
PostPosted: Jun Sun 16, 2019 12:16 pm 
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Joined: Aug Sat 19, 2017 6:55 am
Posts: 55
Location: Glendale, AZ, USA
I can get one locally for $50 or maybe less. I've found a full manual online already.

First question is a 10-400MHz range useful to me? At the moment other than a dvm I have no test equipment. Thinking about getting a software type scope soon. I probably have to draw the line somewhere on old vs new equipment.

Second, other than the fun of fixing it up (assuming it will need work) is it worth it? I love tubes, but should I just get a modern generator and not worry about dealing with a 60+ year old piece. Seems to have a lot of tubes, one worry would be finding replacements if needed. I would imagine a full recap at a minimum would need to be done.

I love the manual for this. Pages on actual operation, and then theory of operation, and then troubleshooting.
Honestly, this would be great for restoration, not so sure about getting it to use. But I'm willing to be convinced either way. :lol:

Thanks,
Russ


Last edited by russosborne on Jun Sun 16, 2019 12:34 pm, edited 1 time in total.

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 Post subject: Re: HP 605D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 12:24 pm 
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Posts: 4387
Location: Sunbury, Ohio 43074
I cannot seem to find an HP 605D ... are you sure that's the correct model?

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 12:34 pm 
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Joined: Aug Sat 19, 2017 6:55 am
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Location: Glendale, AZ, USA
Sorry, 608D. Must be past my bedtime.
thanks,
Russ


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 12:48 pm 
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Location: Utica, NY 13502 (USA)
To be honest, I think you'd be better off looking for an RF signal generator that covers lower frequencies. The most important use for a signal generator is to accurately align the IF stages in a radio. If you like big, boatanchor-style test equipment, an HP 606B would be ideal because it covers most IF frequencies and shortwave up to 65 MHz.

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Dave


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 1:01 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8542
Location: Long Island
If you said you wanted to fix up old VHF and UHF gear for the vintage AM nets, the 608D would be the generator to have. Otherwise, it's a boatanchor which uses an exotic output tube, the 5675, that cannot be substituted with anything else and can be difficult to find when you need one.

Considering that what is considered "shortwave" extends from 1.7-kHz to 30-MHz, and IF frequencies in communications receivers are between 1.8-MHz and 60-kHz, you would still need another signal generator for shortwave and AM broadcast receiver work. There are many better suited generators available, the HP 606A/B mentioned above being one. General Radio made a few models which were good (one of my favorites is the 1001-A which covers an incredibly low 5-kHz to 50-MHz).

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 3:27 pm 
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One rule: If you don't know why you need something, then you don't need it....

For nostalgia, I would love to have both an HP 608 AND 606. The only problem is there would be no room left on my bench for any other equipment....

Starting out, consider getting some "throwaway" test equipment. A basic EICO or Heath signal generator can be had for not much over $10. After using something really basic, you'll know what to look for.

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 3:58 pm 
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Location: Maryland 20709, USA
I have both an HP 606B and a 608 (F I think but don't quote me).

They don't get used since I got more recent HP generators like the 8656B (late production).

When I was using them, the 608 only got fired up for 2-Meter and 440MHz ham receivers.
The 606B was used for everything else.

- Leigh

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 5:36 pm 
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I just got a 606B and a 608C. It was a package deal and a good deal at that. Theres really no big use for the 608C your D is very similar......... It covers VHF and UHF and AM only. I got excited that I could align my Hallicrafters VHF stuff and then remembered its FM and the 608C will be of no use. Its cool and its a very neat piece of test gear but you will have very little need to use it. Its not possible to use it to align any of the "shortwave or Broadcast tube radios....The 606A or 606B is the unit you need!

I have modern equipment and the 606B and 608C. Here is a picture of them all together to show size.............The 606 and 608 are very big and heavy!

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Todd


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Sun 16, 2019 5:56 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 238
I used to own an HP608 and frankly, for what it can do, it's too big and heavy. I got it for nothing, and gave it away. I now have much better units and again, my cost is zero.

The 608 does not have FM and doesn't go low enough in frequency for lots of HF purposes. It's built like a tank but for the space it consumes, is about as valuable as having a tank in my garage.

The important parameters for a generator (or maybe two generators) are:

Calibrated output amplitude
Frequency from 100 kHz to either 60 MHz or higher
AM (and FM if you work above 30 MHz)
Accurate frequency calibration (modern synthesized generators are crystal controlled)

I not only use my generators as signal sources but as frequency calibration. Calibrating an S meter is important also, so accuracy of output is important. When I want S9, it should be 50 microvolts or -73 dBm and reasonably close to correct.

If you are working with a modern transceiver, you probably should have a sweep function so you can adjust the many little coils in the bandpass filters.

I have an old but perfectly working Measurements Model 80 (2-400 MHz) I want to sell cheaply. I also have one of the prized military units, the AN/URM-25D that goes from I think 10kHz to 50 MHz. Both have calibrated output amplitude and AM plus incidental FM. (Incidental FM is what you get when you modulate the oscillator and it's useful for FM work.) Anyone interested in these contact me privately.

The Measurements 65-B as well as the HP version (HP 606?) are good instruments but the HP has a buffer after the oscillator that eliminates the incidental FM.

The widely available E-200-C from Precision may have reasonably accurate frequency calibration but its amplitude is totally uncalibrated. And in fact it puts out substantial signal even when the output is set to zero. No good for sensitivity measurements. Stability is sloppy as well. Competing units from Heath and EICO and others are equally bad. They all have distorted waveforms which they paint rosily as 'rich in harmonics'. They even have extra dial scales calibrated in harmonic frequencies. Stay away from those.


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 2:19 am 
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Joined: Jan Mon 28, 2013 9:35 pm
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Location: Santa Rosa, CA
I've owned and used the HP 606 and 608 for 25+ years. Yes, they are big
and the 608 uses an odd oscillator/buffer tube. But if you consider performance
per dollar (or pound) they are hard to beat. Since it sounds like you
don't have much test equipment and enjoy working with tube equipment
I'd encourage you to get the 608 and keep an eye out for a 606.

One thing no one has mentioned yet is the excellent shielding and attenuator
in the 608. Don't know of any signal generator that is better in this
respect.
Steve

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 3:56 am 
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Joined: Oct Sat 23, 2010 5:43 am
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Location: EAST COAST
A very good RF generator is a Heathkit IG-42 or a LG-1.
The circuits are the same, and very well shielded.


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 5:59 am 
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Location: Lincoln City, OR
Greetings to the Forum:

Be careful about the suffix on the 608 series of generators. The 608C and the 608F cover the 450 ham band... the 608D does not. The 608F has provision for a tuning stabilizer... I forget the HP number for this box. I had a 608F and the tuning stabilizer and gave them both away.... no space and the pencil tubes used in the 608 series generators are made of unobtanium.

Regards,

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 7:12 am 
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Joined: Aug Sat 19, 2017 6:55 am
Posts: 55
Location: Glendale, AZ, USA
Thanks, all.
I think I will wait and get something else that will be more useful at this point for me.
I need test equipment that I can use right away, not another project.
I just am so attracted to this boat anchor stuff. :oops:
And I have to keep reminding myself just how old this stuff is. I am still seeing it through the eyes of a 15 year old kid just into electronics, 45 years ago.
Russ


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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 11:30 am 
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russosborne wrote:
"I have to keep reminding myself just how old this stuff is. I am still seeing it through the eyes of a 15 year old kid just into electronics, 45 years ago."
Russ

This syndrome, as much as I have tried to shake it, I have not. The allure is just too alluring. :|

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 11:50 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 4387
Location: Sunbury, Ohio 43074
There's nothing inherently 'wrong' with getting the wrong instrument to play with. Depending on your budget and time of course. But the more you learn, the more you'll know. It's a simple principle. There aren't any schools for this type of thing anymore, although there do exist someonline tutorials for general info and the even more occasional review of the restoration of some specific device or tester.

Most have started out with very basic, and very cheap, equipment and upgraded as both knowledge and needs increased.

Off this subject, someone earlier mentioned a difficult to obtain tube in some of the 60x HP series.... there are always several such pencil tubes up for sale on our favorite auction site, and really don't cost that much. The original tube however is probably going to last another 100 years.

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Mon 17, 2019 1:33 pm 
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I am going to be the wet blanket. I had the military version--TS-510a as I recall. Brand new surplus in the military aluminum shipping crate. It had way too much drift for my needs, and my unit had excessive signal leakage as well. Went through heck trying to align a Sinclair hybrid ring duplexer on a remote repeater site--the drift and leakage was a major issue. I could understand that it if the unit had years of use and abuse, but this was a NOS instrument. I don't recall if it ended up in the local town landfill, or if I found a home for it. A fellow ham in town had trouble giving his away. You could not GIVE me one. A 606 I'd keep, even though I don't have a need or room for one because it is best in its class.

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Wed 19, 2019 10:41 pm 
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Location: Monterey California USA
Same thing happened to me. I was trying to do some repeater tuning with a 608F at the Naval Postgraduate School lab about 40+ years ago and there was so much leakage that it was useless. Got another one, same issue. In a tantrum I went to the cal. facility and complained. "Oh, we don't check the attenuators or the shielding," the chief said, "we just check the dial calibration." I requisitioned a just arrived HP 8640B and all was well. I then bought a Measurements 560 FM for use at home and that was a great little generator that you could actually carry.

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 Post subject: Re: HP 608D-worth getting/fixing up for shortwave testing us
PostPosted: Jun Fri 28, 2019 3:28 pm 
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It is possible to use a service grade RF generator for basic stuff provided a digital frequency display is added along with a Vernier drive for the frequency adjust knob.

I did just that with a Stark LSG-10A RF generator and it works good enough so that I could properly align my Collins R-390 with it.

I would suggest though that if you can get a better RF generator, do so.


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