[MRCA] RF Generator wanted
Al Klase
ark at ar88.net
Thu Mar 19 15:33:47 EDT 2020
Ray,
You need to collect the whole set of HP generators. Beyound the 606 and
608 there are a couple others that go way up into the microwaves. Have
an extra bedroom?
The HP-8640 has an input to the counter, so it eliminates an instrument.
Al
On 3/19/2020 3:11 PM, Ray Fantini wrote:
>
> Another Thought, if space were not an issue would look into the huge
> heavy HP-608 would go well with my FR-38 but alas it has been
> relegated to living inside a sealed transit container out in the garage.
>
> https://www.youtube.com/watch?v=3ka1wwvex5o&t=36s
>
> YouTube video of when I had it in the shop. You can also see the
> offending Motorola. Think the HP-6840 would look good next to the
> newer HP counter.
>
> Ray F/KA3EKH
>
> *From:* mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net>
> *On Behalf Of *Al Klase
> *Sent:* Thursday, March 19, 2020 3:00 PM
> *To:* mrca at mailman.qth.net
> *Subject:* Re: [MRCA] RF Generator wanted
>
> Ray and the group,
>
> What you're talking about is a laboratory-grade signal generator.
> Here's a couple I know of first hand:
>
> HP-606: Tube based, Bigger than a braedbox, LF thru HF, calibrated
> attenuator, repairable, Most seem to work without a fuss.
>
> URM-25: Essentially a reduced-size military version of the HP-606.
> Many need to be recapped - that's a PITA but doable, Small size of
> the freq. dial is NFG for old eyes.
>
> HP-6840: 400 KHz - through UHF, Digital readout, AM and FM
> modulation. Someone mentioned the gear problem with the band switch.
> I handle mine gingerly. When one of these stops working it makes a
> nice wheel chock unless you're a talented technician with a lot of
> time on your hands.
>
> Don't discount the old-buzzard General Radio stuff. The 1001-A and
> the rally old 405 come to mind.
>
> The Eico/HeathKit/RadioShack things are all toys.
>
> Al
>
>
>
> On 3/19/2020 2:29 PM, Ray Fantini wrote:
>
> Signal generation is easy, the problem now days is that I have
> reached the point where I want to confirm receiver sensitivity at
> different frequencies so you have to have the ability to calibrate
> the output of the generator and a calibrated attenuator to be 100%
> that the radio is working correctly. These early synthesized
> radios suffer from insensitivity and in the case of USB only
> radios when trying to copy AM if the time base in the radio is not
> dead on it can be an issue. The GRC-106 receivers exciters
> RT-662/834 produce an annoying heterodyne if not dead on carrier
> when used in AM mode. They use the same product detector in USB or
> AM with only inserting a carrier in the AM transmit mode to
> produce a quasi AM signal.
>
> The big Motorola 2000 series monitor produces signals at
> calibrated levels but get the idea that the AM on it was only an
> afterthought, when doing VHF or UHF FM its great but working on
> this old HF/SSB stuff is requiring a different tool set. Had to
> come up with a power meter that works down in the 2 to 30 MHz
> range along with things like the two tone generator for testing
> the transmitters and amplifiers, now I want to be able to provide
> a clean low distortion AM signal for checking distortion on the
> receive side.
>
> Something like the things years ago when working with VHF FM stuff
> and using the SINAD meter to tune for best audio.
>
> Have not pulled out one of the older Motorola Service monitors or
> a Cushman to see if it has better AM, have been saving them for
> you to get you working with one.
>
> Ray F/KA3EKH
>
> *From:* comcast <kg2bz at comcast.net> <mailto:kg2bz at comcast.net>
> *Sent:* Thursday, March 19, 2020 2:08 PM
> *To:* Scott Johnson <scottjohnson1 at cox.net>
> <mailto:scottjohnson1 at cox.net>
> *Cc:* Ray Fantini <RAFANTINI at salisbury.edu>
> <mailto:RAFANTINI at salisbury.edu>; milsurplus at mailman.qth.net
> <mailto:milsurplus at mailman.qth.net>; MMRCG at groups.io
> <mailto:MMRCG at groups.io>; Mrca Mailing List <MRCA at mailman.qth.net>
> <mailto:MRCA at mailman.qth.net>
> *Subject:* Re: [MRCA] RF Generator wanted
>
> what about using an lm or bc221?
>
> Sent from my iPhone
>
>
> On Mar 19, 2020, at 12:09 PM, Scott Johnson <scottjohnson1 at cox.net
> <mailto:scottjohnson1 at cox.net>> wrote:
>
> My choice, for the last thirty years, is the HP 8640B. I
> believe it to be among the best generators for receiver
> measurement and alignment. The only problem is the nylon
> gears, which tend to shrink and crack from the brass hubs.
> There are people making and selling gears, and even at $300
> for a set that, it is still worth owning one.
>
> Options include a doubler to 1024 MHz, reverse power
> protection (recommended),and variable frequency modulation.
> The Military version in the yellow case is to be avoided in my
> opinion, as it lacks phase locking and is generally a pain in
> the keister, unless you (like me) collect such things.
>
> Scott V. Johnson W7SVJ
>
> 5111 E. Sharon Dr.
>
> Scottsdale, AZ 85254-3636
>
> H (602) 953-5779
>
> C (480) 550-2358
>
> scottjohnson1 at cox.net <mailto:scottjohnson1 at cox.net>
>
> scott.johnson at ieee.org <mailto:scott.johnson at ieee.org>
>
> *From:* mrca-bounces at mailman.qth.net
> <mailto:mrca-bounces at mailman.qth.net>
> <mrca-bounces at mailman.qth.net
> <mailto:mrca-bounces at mailman.qth.net>> *On Behalf Of *Ray Fantini
> *Sent:* Thursday, March 19, 2020 8:04 AM
> *To:* milsurplus at mailman.qth.net
> <mailto:milsurplus at mailman.qth.net>; MMRCG at groups.io
> <mailto:MMRCG at groups.io>; Mrca Mailing List
> <MRCA at mailman.qth.net <mailto:MRCA at mailman.qth.net>>
> *Subject:* [MRCA] RF Generator wanted
>
> Everything old is new again! Been working a lot with repairing
> a lot of GRC-106 receiver exciters and noticed that my
> Motorola Communications Service Monitor produces a lot of
> phase noise and poor-quality AM on the HF bands. Decided that
> what I need is something like an old school URM-25 or maybe if
> I can find one a URM-144/SG-823 being I already have a SG-376
> that I got last year that I have been using a lot for SSB work.
>
> As always not looking to spend a bunch of money on this but
> can always do a trade. Lot of crazy prices for URM-25
> generators on eBay but use to seeing them at Hamfest for $20
> to $50 price range. Did not realize until recently that you
> more often than not need vintage test equipment for working on
> vintage radios.
>
> It’s amazing what happens when you take modern items like the
> new generation of digital scopes today and look at things like
> modulation levels for AM carriers! Or operate DVM in high RF
> environments.
>
> Ray F/KA3EKH
>
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> --
> Al Klase – N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
--
Al Klase – N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/
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