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Reviews Categories | Specialized Amateur Communication Products | Palomar LF Converter VLF-A Help

Reviews Summary for Palomar LF Converter VLF-A
Reviews: 5 Average rating: 5.0/5 MSRP: $99.95
Description: VLF-->LF Converter with 80M output
Product is not in production.
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W2RKJ Rating: 5/5 Mar 12, 2014 17:44 Send this review to a friend
Unbelieveble!  Time owned: 0 to 3 months
Being an pilot, I've listened to beacons since I became a ham. The best receivers for beacons I had were a Kenwood TS-450SAT and a Drake SW-2. They both aren't bad. I was considering buying a Harris RF-590(A) for beacons. I decided to instead get a completely overhauled and freshly painted Collins R-390A with the intention of getting a converter. I read the reviews here and was convinced to give this a try. Well that was a decision I truly do not regret. This Palomar Converter is an outstanding performer. I couldn't believe it. I was expecting a noisey audio with a bunch of trash, Not at all. Setup was a breeze and the craftsmanship is truly first rate. The beacons I could copy on my other gear was OK but this Palomar Converter from Hamcrafters made the beacons slam into my QTH with a 75 meter 3 band inverted V dipole (Apex at about 23 feet). When this weather on the east coast clears up I'm looking to put up a EWE antenna and then lookout. I can't say enough about this converter but what I can say in a word is OUTSTANDING!
K0OD Rating: 5/5 Mar 8, 2013 19:57 Send this review to a friend
Palomar VLF Converter and its Use with Flex Radios  Time owned: 3 to 6 months
Review of Palomar VLF-B Converter and its Use with Flex Radios

U.S. hams should soon get their first permanent longwave allocation since 1912. Even now experimentally licensed stations are active in RF’s “basement” and can be heard on various modes with simple receivers. One thing is certain, longwave hams will transmit with inefficient antennas and low power. They will utilize a full arsenal of sophisticated weak signal modes including WSPR and QRSS. You’ll want top notch receiving equipment to get the most out of this new allocation.

Few ham receivers hear well below 540 kHz. My Flex-5000 transceiver is perhaps the worst. It picks up absolutely nothing below 530 KHz except a cacophony of broadcast artifacts. What a waste! Flex radios otherwise provide cutting edge technology for weak signal reception. Flex, for instance, offers lab quality stability and frequency accuracy to <1 Hz. Its fantastic panadaptor is useful for analyzing longwave digital signals.

Flex owners have discussed ways to improve LF performance. Low pass and band pass filters hold promise, but it’s hard to predict their effectiveness in any specific location. I’ve gone with another approach which is to use a converter to move longwave signals up to a range where my receiver excels.

Good low frequency reception is mostly about rejecting unwanted noise from a myriad of natural and man-made sources. Virtually all receivers and antennas have plenty of sensitivity. The conversion itself can introduce problems related to intermod and overload by nearby high-powered stations.

I opted for the venerable $89.00 Palomar VLF-B converter which arrived within a few days from K1EL Systems. Its specs say it transforms the 10 kHz-500 kHz band to 4.010 MHz-4.500 MHz by mixing incoming longwave signals with RF from its 4 MHz crystal controlled oscillator. With most receivers one would simply ignore the preceding “4” from the readout to get the actual listening frequency. I was concerned that the converter wouldn’t cover around 505 kHz where some ham activity takes place. But you can easily hear through the lower portion of the AM broadcast band.

I noted just one or two trivial instances of weak spurious AM BCB signals intruding on reception. At last, hams, NDBs, WWVB and even European LW AM broadcasts popped out from the background as I tuned my Flex. Digital ELF stations from thousands of miles away can be heard almost down to direct current. My antenna is hardly ideal: a DX Engineering 43’ HF ham vertical in a St. Louis suburb.

Twelve years ago QST, in reviewing an earlier version of the Palomar converter, wrote that oscillator error produced readouts that were 7 kHz off. My new converter is off by 318 Hz across the receiving range. Unfortunately it has no trimmer for correcting that. The manufacturer tells me that replacing capacitor C1 in my unit with one of 10 pF should move it close to the proper frequency.

TRANSMITTING INTO ANY CONVERTER CAN DESTROY THE CONVERTER. Refer to the manual to assure that you connect the Palomar properly. At first I used Flex-5000’s RX1 input which is a simple receive-only BNC connection. I eliminated the 318 Hz frequency error with the Flex RIT.

The Flex-5000 provides a more elegant way to connect a converter through the transverter (XVTR) input. Clicking on XVTRs brings up the XVTR Setup Form where the LO Offset should be set to -4.000. That removes the preceding “4” so the readout shows WWVB, for instance, at 0.060.000 rather than at 4.060.000. I corrected for my Palomar’s oscillator error by entering -0.318 in the LO Error box. The converter selection button on the Flex “Front Console” can even be relabeled to read “VLF” if desired. After a few other simple form settings the Palomar is fully integrated into the transceiver.

The sturdy Palomar VLF-B consists of a three stage low-pass filter, crystal LO, and a 1496 mixer chip. I counted about 15 capacitors and 13 resistors, none of them SMD. With its LM7809 voltage regulator, the simple converter is remarkably drift-free. No schematic is provided in the 4-page manual. The front panel switch turns the converter on or off and bypasses it when turned off.

The VLF-B brought the longwave performance of my Flex-5000 to life. However a converter is actually a minor component in a low frequency receiving system. Important too are antenna type and placement, feed line, man-made noise sources including lighting and power lines, and proximity of powerful broadcast stations.
N4UE Rating: 5/5 Sep 15, 2009 14:06 Send this review to a friend
Perfect when connected to a 756PRO  Time owned: more than 12 months
I have had one of these little jewels for a couple of years. As already mentioned, LOTS of radios are 'hard of hearing' below the BC Band.
I love connecting the VLF converter to the 756PRO.
This allows you to 'see' activity in this part of the spectrum. Sensitivity is excellent and all you can use.
Have FUN!!

AF4KK Rating: 5/5 Apr 4, 2007 15:04 Send this review to a friend
Great for LOWfers!!!  Time owned: more than 12 months
Most receivers aren't very sensitive below 500 kHz or so but the Palomar (sp?) lf converter works wonders! It helps to pull in those beacons and other stations waaaayy down to 10 kHz or so! I love this little device! It does what it's supposed to do without any fuss or muss!
W4OP Rating: 5/5 Nov 22, 2005 19:47 Send this review to a friend
Great Product with great support  Time owned: more than 12 months
I own an Icom IC-756 PRO II. One of my interests is the spectrum below 500KHz. I have a 7' shielded loop with a broadband preamp- yet I was not hearing near the number of Non-Directional-Beacons with this set up as I was hearing on my lowe HF-150. Sensitivity checks showed the PRO II to be quite deaf below 500KHz.
I had an older Palomar VLF converter and hooked it up through the RX ANT port on the PRO II. Now LF is alive with signals- all over USA and S. America. Switching back and forth reveals a dramatic difference.
In order to run ARGO software effectively I needed 1 Hz accuracy- Palomar kindly sent me a manual for my converter with a written explaination showing how to add a trimmer to the oscillator to net the crystal.
Great company.

Dale W4OP

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