The AM Forum

Hi to all:

I just added the Hammarlund HQ170A VHF to my shack.  I needs TLC. 
Can any one recommend a signal generator to align the radio?
The manual says I will need a signal generator the can produce
unmodulated signals of: 60 KCS (KHz), 455 KCS, 3035 KCS and RF range
from 1.8 MCS (MHz) to 145 MHz. 

Can't wait to align this radio and replace needed parts.

Chuck

does it have a crystal calibrator? often that is enough to get you in the ballpark, and peak things up...


                   _-_-bear

Bear:
Yes it does.  Thank you for the tip.
Chuck

If you just "peak" all the cans up, you'll wind up with a crappy receiver. Follow the alignment procedure as described, but note, Hammarlund also issued an addendum for a portion of the alignment. This is not a receiver that you just diddle diddle all the slugs for max. Having a sweep generator, besides a good signal generator that gets down to 60 KHz, would also be a plus.

Hey Chuck,

    As with the 100kc Calibrator the Harmonics from your sig,
Gen. can be "Handy".

GL

/Dan

Pete and Dan:
How would a sweep generator be a plus over a non sweep signal generator for aligning this radio.
Do you know where I can find the addendum to the alignment procedures?  Thank you for this tip.

Can anyone recommend a signal generator to align this radio?

Chuck

HP3325A or B is a great sweeper that works up to 20 MHz. Then an HP8640B will get you to 455kHz to 500 MHz. The 8640B is one of the cleanest generators known to man.
Dats what i use

WA1GFZ and All:

Thank you for the signal generator tips.

I noticed when I switch between lower side band to upper side band, when in the CW mode, the received signal
is almost the same strength on both above side bands. 

Any other suggestions for signal generator to align this radio?

Chuck

 A "regular" signal generator is needed for alignment. I mentioned the sweep generator as an additional plus because it allows you to adjust the 455 KHz IF's for a nice response. It's not necessary as part of the Hammarlund alignment but it does allow for smoother sounding AM signals.

HP-606A or B are good vintage signal generators, that go from 50 KHz to 65 MHz, and can be found for real cheap at flea markets. A lot depends on how deep into your pockets you want to dig.

(http://www.hpmemory.org/pict/wall_a/606b.jpg)

The 60KHz will stop a 8640B in its tracks, can't go that low. Got one and I like its whistles & bells. Another option and at times cheap is a URM-25D. Used with a freq counter, it will get the job done.

Can't remember the high end of the URM?

Craig,

I have an F model  Aligned many a radio with it.  Find yourself a function generator with the sweep function for the low IF frequencies to do the IF stages.  I have one that will go to 10 Mc.  Then any RF gen will do the RF. 

HP606 will work if it is working properly. Let it warm up for a few hours.

This is my choice.

http://www.testequipmentdepot.com/usedequipment/hewlettpackard/signalgenerators/3325a.htm?gclid=CJydudqt1a0CFcfe4Aod_Wwbmw

I've used this generator for decades in the shop and it's really great. Plus being a function generator you get triangle and square wave generators.  It has the added benefits of a HP-IB where it can be controlled using HP BASIC.  You might not need that feature today but later on, who knows?

That's not a bad price on this referenced web site either.  It's a synthesized generator plus a sweeper along with computer HP-IB control - a real bargain.  Additionally, it can be phase locked with another generator

Oh yeah - it can be Amplitude and phase modulated too.

Al

Al, the HP3325A/B can become a wonderful SBE exciter.
I see them go for around $100. I use mine all the time. The only issue is the limited attenuator range but a couple external ones or a step attenuator takes care of that.
Also goes down to audio range. Audio sweeper is good for checking audio response.

As you can see, asking "what's a good signal generator" is like asking "what's a good receiver". Get what you can afford, covers the frequencies of interest, works, doesn't look like it was dragged for a hundred miles attached to a bumper of a truck, and doesn't have 901 features and options that requires a 5 pound manual to figure out how to use it.

SBE? Hmmm.  Wonder if an arbitrary generator would be better but your point is taken.  Fun generator.  Good to know about the lower prices.  I'm spoiled here at Raytheon.  I'm going to miss all my cool toys when I'm gone

Al

Al, just set it up as a slow sweeper covering a few kHz.

Any other suggestions for signal generators?
Chuck

Chuck, the HP8640 is an excellent generator. If you get one, make sure you have a flat open space for it too position down flat. Do not set it on the floor vertical. If you can find one with the option audio oscillator as a variable, not fixed 400 Hz, 1 kHz, that might get you the 60 kHz you need as the audio oscillator output port is available and is adjustable (amplitude and frequency). Or you could build some divide by 2 blocks and LPF for freq's below 450 kHz. The HP8656 is your next best bet, and check out this cite for comments:

http://www.ko4bb.com/Test_Equipment/Signal_Generators.php

An HP8662 if you can find one in clean shape and not to expensive, is a fantastic generator and competive to the 8640, however it is fully synthesiszed with millihertz steps and will cover your desired frequency range. Its phase noise etc... is incredible for its vintage.

Oh, on the 8640, a major issue is leakage. If possible check it out prior to use. The RF gasketing of that generator must be done correctly. It is fine fresh from the factory but over the years and as repairs are done, people foul up the gasket integrity. If you are trying to measure MDS on a RX, you may be dissapointed.

Finally, consider rolling you own if you have a decent junk box. I have some 100 MHz TCXOs just waiting for a PLL to wrap around them! See the for sale section of the forum :)

Crap cable is usually a bigger problem than 8640B leakage. RG58 leaks very bad. You really need to use double shielded cable like RG223 or RG141B. BNC connectors also suck for leakage when you want to play below -130dBM.

W4AMV, WA1GFZ and all:

I will look at the link regarding the HP8640 series of signal generators.   I don't have much experience
using these instruments.  But, I am wiling to learn more to help keep the radios running correctly.

Thank you for your help.

Are there any other suggestions?

Chuck

The 8640B is very easy to use. The 606 is even easier but not as stable and uses tubes. I've bought 8640B from $100 to $300. I have 3 and 1 hanger queen.
Yes, they want to lay flat so grease from the cavity oscillator lead screw doesn't flow into the cavity.

Aint nothing wrong with a 606A or B after a simple overhaul, even the tubes used are readily available. I started with one and now have another, total investment $90. After a 30 minute warmup they are more than stable enough even for a HRO-500 and RA-17. The only downside for some is the size. They seem to be catching on more with the house radio restorers so prices may be going up.

I also have a 8640B but those damn gears are fragile so I only use it on riceboxes on another bench. Use the recommended accessory HP-11710B downconverter and it will get you down to 10KHz. Lots of junk on Fleabay so caveat emptor.

Any URM-25 is going to need an extensive (lots of leaky caps) overhaul to be stable and accurate for IF and filter alignments but they always drift above about 10MHz. I lugged one in the USN for many years and thats what I bought for home about 25 years ago. Its OK for old AM/SW house and auto radios (and the more basic boatanchor) which is on a 3rd bench. I see many in nice shape needing an overhaul for $50-75.

Anything as good or better is going to be pricey and may not be justified just for a radio or three. I do this stuff as a biz plus hobby and havent found the need for kilobuck gear yet....

You can also use a ricebox with a transverter port or a couple of big pads followed by a switchable attenuator. Done that a few times and didnt blow anything up......YMMV.

Carl

I landed a late model 8640B with new gears for $100. 5 volts was dead. Pulled out the regulator board and plugged back in and it still works.

I'll give you $125 at the Spring Nearfest ;D

Agree, good cable and proper connector and dressing is important. However, the level of leakage I was addressing in the 8640 and for that manner any generator that is not properly reassembled or maintained will not be corrected by the cable or connector selection. As a simple test, Carl, if you own a 2 meter or UHF handheld you can use it as a test vehicle when you obtain your generator. Assume the generator goes to VHF or for HF construct a magnetic loop for your HF RX (this is documnted in the 8640 manual). With the generator ON, pass the loop or whip all around the generator box. Set the attenuator to its min level and terminate all generator ports (into 50 ohms). You should hear ZIP. I have seen a 8640B radiate so bad that pickup was obtained from a foot away! Not a fault of the HP, but of its care and reassembly. Incidently, there was an early version of the B which did not have an EMI screen shield in front of the digital display. Radiation from the display was horrific. Soooo, check the display see if you see the BLACK grid EMI shield embedded in the RED filter.

Carl learned about leakage almost 50 years ago in a screen room at National and later with Tempest security clearance at Sanders Associates and Wang Labs.;D

oops, I meant to say Chuck! Sorry ::)

Does anyone have a recommendation where to look for these signal generators besides Ebay, CraigsList, Toronto Surplus Fair Radio and ham fest?

Chuck

Just search on HP. This way you can see if there are any HP3325A/Bs around.
HP made many different generators.

Hi to all:

Do you think this product and procedures would work when aligning the Hammarlund HQ-17A-VHF?

http://comtekk.us/sinad.htm

Chuck

That's just a SINADer.  Not needed, there's no adjustment in a HQ requiring a min reading on a SINAD meter.

W3JN:
Thank you.
Chuck

I also have the HP8640B and it's been worth its weight in gold to me.  Not dirt cheap, but they're plentiful.  Just be careful to find one that has good gears...replacements are hard to find.

If you want to get a sweep generator, which I also recommend, consider a Hickok 288X.  It's late '40s design and was decent generator for the day, just the thing shops would have used for IF alignment.  I paid $10 for mine at a hamfest, and all it needed was to get a couple of controls freed up.  It's plenty stable enough for swept IF alignment.  I don't trust its analog frequency dial, so I use the '8640B to set the frequency.

All the information you could want to know about it is in the manual: http://bama.edebris.com/manuals/hickok/288x/.

73,
Jim
W2BVM

Jim:
Thank you. 
Chuck

Jim:

Can the HP8640B put out a non modulated (cw) signal?  The manual for the Hammarlund HQ-170A alignment mentions this?

Chuck

What does the group think about the Marconi 2018 signal generator?

Chuck

It doesn't get down to 60 KHz which is what you need for Hammarlund IF alignment:
Marconi 2018, 80KHz-520MHz

The '8640B will generate AM, FM and unmodulated signals.  However, I lost sight of the fact that you need 60 KHz for for the Hammy.  The '8640B spec only goes down to 500 KHz, but they actually go a bit lower...I've used mine for 455 KHz alignment.

Jim

Copied from my post on Page 1

Carl, Jim and all

Thank you for the good information.  Can the down converter, HP11710B, for the HP8640B put out a cw signal (non modulated)?

Chuck

A double balanced mixer willl do the same thing. Take the 5MHz reference and mix it with the generator output to get a lower frequency. add a low pass fillter and done. My 8640bs get down to about 450khz. A cheap function generator with sweep function is far better for tuning an LC filtered IF. A scope will display the bandpass so you can tune it flat if the sweep out ramp controls the horizontal position of the display.

Can you recommend a function generator with sweep function?

Will the Hickok 5900A function generator work?  I don't see any reference that the Hickok 5900A has the sweep function?  Does anyone know if it has the sweep function?  

I am not sure if the down converter for the HP8640B has the non modulated (cw) output signal capability.  

Thus far I have not found an HP606B for under $700.00.  This is to  much.  The least expensive working HP8640B has been about $2600.00.  This is to much.  

I have not given up.  Thank you for your help and patience.

Chuck

I just watched a video showing the alignment of the IF's of an old radio.  The gentleman was using a function generator that had sweeping ability.
He plugged the output into a an oscilloscope for visual.  I also read a bit about this and it seems using a function generator with sweeping ability and with markers along with a scope would be a better approach than my first thoughts of obtaining just a signal generator.

My question is, do I still use a non modulated (cw) signal from the function generator or do I use a modulated signal?  What type of modulation, if needed, should one use (am, FM etc.)?  The Hammralund HQ-170A-VHF manual says to use a non modulated signal (cw)l from a signal generator.  However, I think the use of a function generator along with the scope would be better.  I think a frequency counter would be needed?

Anyone have a follow up to my thoughts.  Am I on the right track?

What would be a good choice for this function generator.  That is, if this is the correct way to go?

Thank you for any and all help with this challenge.

Chuck

 

How do you plan to align the RF section of the receiver with a function generator?

Chuck there were several versions of function generators that have (had) the sweep function.  You choose a frequency with the analog output as you saw then the sweep function will alter the frequency back and forth at the setting you choose.  I have one made in Israel that I paid 10 dollars for at a hamfest that is solid state and very stable.  To avoid paying a lot, I suggest you go to some of the bigger fests and look rather than shop ebay if you can.  The sellers on eBay sometimes are a bit exravent in their listings and I don't want to buy something I haven't held or seen.

The things are not in favor because not many people do this type of thing so don't be afraid to dicker on the price.  There were 3 on the table where I found the one I have and it was marked 25 dollars the other two cheaper.  It will tune from near zero to 10 megacycles so you could use it for all IF frequencies and, even RF up to 10 megacycles.

The HP equipment is usually very expensive and I don't own any, mostly because of that.  I have an old AN/URM 25F that I have used successfully for years.   Mine is stable enough to do an aligment at 10 meters.  On AM, much below 3 microvolts is great on most old equipment so the leakage doesn't bother much.  If you will watch you may find one, get a D or F version, in good condition and they probably won't be much.  I also have a CM-1 that is digital and will sweep frequency.  One of the early service monitors, it is nice to have, but with a cheap frequency counter attached to the 25F high output and the receiver attached to the attenuated output, I can do all the RF alignment I want it is just a bit more tedious.  Altogether I spent near 50 dollars for that equipment and got my 100 meg scope for another 50.   For me, this is a hobby and I don't want to spend a lot of money.

This thread is going in circles

(http://www.brainboggling.com/wp-content/uploads/2008/03/disappearing-dots-illusion.gif)

Jim and all:

Thank you for the advice.  At present, I think I will look for the sweep generator (and maybe a diode detector) to use with my scope to align the IF section of the receiver.  Not sure if I need the diode detector?

Chuck

Of course. All it does is convert the 8640B output to a different range, you use all the regular functions and simply do the frequency conversion between your ears.

It will work with most any other sig gen that has a stable output from 50-60MHz. Also see this for some sweeping info using one.
http://www.cliftonlaboratories.com/adventure_of_the_hp_11710b.htm

I bought mine for $75 when the market was flooded with them by the USAF and the surplus bandits were having a price war :P

Option 001 for the hp8640B is the internal audio oscillator.  Its range is 20Hz to 600KHz.  I was thinking I would be stuck with audio tones only with the down converter, internal that is.  I see with your link there is an external down converter.  

Thank you for this very good tip!

Chuck