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Signal Generator for Hammarlund




 
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Author Topic: Signal Generator for Hammarlund  (Read 16328 times)
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aa5wg
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« on: January 15, 2012, 11:04:34 PM »

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
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WBear2GCR
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« Reply #1 on: January 15, 2012, 11:23:17 PM »



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


                   _-_-bear
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_-_- bear WB2GCR                   http://www.bearlabs.com
aa5wg
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« Reply #2 on: January 15, 2012, 11:59:11 PM »

Bear:
Yes it does.  Thank you for the tip.
Chuck
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Pete, WA2CWA
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« Reply #3 on: January 16, 2012, 03:25:53 AM »

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.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
N8ETQ
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« Reply #4 on: January 16, 2012, 06:57:51 AM »


Hey Chuck,

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

GL

/Dan
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aa5wg
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« Reply #5 on: January 16, 2012, 08:36:09 AM »

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
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WA1GFZ
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« Reply #6 on: January 16, 2012, 08:42:59 AM »

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
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aa5wg
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« Reply #7 on: January 16, 2012, 09:52:45 AM »

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
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Pete, WA2CWA
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« Reply #8 on: January 16, 2012, 02:02:46 PM »

Pete and Dan:
How would a sweep generator be a plus over a non sweep signal generator for aligning 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.

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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
WD8KDG
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« Reply #9 on: January 16, 2012, 02:26:37 PM »

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,
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Jim, W5JO
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« Reply #10 on: January 16, 2012, 02:54:38 PM »

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. 
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WA1GFZ
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« Reply #11 on: January 16, 2012, 03:07:37 PM »

HP606 will work if it is working properly. Let it warm up for a few hours.
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w1vtp
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« Reply #12 on: January 16, 2012, 03:24:13 PM »

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
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WA1GFZ
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« Reply #13 on: January 16, 2012, 04:51:37 PM »

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.
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Pete, WA2CWA
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« Reply #14 on: January 16, 2012, 05:11:54 PM »

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.
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w1vtp
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« Reply #15 on: January 16, 2012, 05:38:18 PM »

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.

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
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WA1GFZ
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« Reply #16 on: January 16, 2012, 08:32:12 PM »

Al, just set it up as a slow sweeper covering a few kHz.
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aa5wg
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« Reply #17 on: January 17, 2012, 02:52:35 AM »

Any other suggestions for signal generators?
Chuck
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W4AMV
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« Reply #18 on: January 17, 2012, 10:24:54 AM »

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 Smiley
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WA1GFZ
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« Reply #19 on: January 17, 2012, 10:38:24 AM »

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.
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aa5wg
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« Reply #20 on: January 17, 2012, 10:49:57 AM »

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
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WA1GFZ
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« Reply #21 on: January 17, 2012, 11:50:34 AM »

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.
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KM1H
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« Reply #22 on: January 17, 2012, 01:39:25 PM »

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
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WA1GFZ
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« Reply #23 on: January 17, 2012, 02:39:43 PM »

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.
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KM1H
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« Reply #24 on: January 17, 2012, 07:38:18 PM »

I'll give you $125 at the Spring Nearfest Grin
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