Category Archives: Ham Radio

Bob recalls working at Harris and putting the RF-505A on the air

In response to our post mentioning the Harris RF-505A, SWLing Post contributor, Bob LaRose (W6ACU), writes:

I know the RF-505A very well. It was introduced in about 1969 while I worked at Harris in Rochester. I started working there as a Co-Op student while at RIT and then after I got my BSEE I joined them full time, initially as a Field Engineer but quickly found my way into Marketing and eventually Sales.

Right after the first version came out, the RF-505, I took one home to my parent’s house for a weekend and did some SWLing with it. It was very neat in one respect – it tuned ISB (Independent Side Band) and in those days there were a number of utility stations using ISB (separate traffic on each sideband). To an SWL some of the most interesting of these were the VOA point-to-point links from the East and West Coast, each carrying two simultaneous program feeds for the overseas relay stations!

While overall a good receiver my personal results on the sensitivity of the original RF-505 were not very positive. On the bench with exactly a 50 ohm source it looked good but on a real world antenna it was pretty numb. Eventually, after a lot of internal arguments, they came out with the RF-505A that included a tunable active preselector as shown in the photos. Problem solved.

For a ham or SWL the RF-505 was a real pain in the butt to tune. You could dial in any exact frequency but the decade switches didn’t roll over (either mechanically or electrically) so you had to do a lot of knob twiddling to do any kind of band scanning. The detents on the switches connected to the knobs were pretty stiff so you could easily take some finger skin off tuning around!

If I remember correctly Harris built them for about a five year period and then replaced them with the RF-550, which was a monster of a receiver with all kinds of advanced features. It included a keyboard with electronic display.

Great memories!

Thanks so much for this RF-505A insight, Bob! I had a hunch that band-scanning wasn’t the RF-505A’s strong suit–it would be incredibly cumbersome to scan with so much “knob twiddling.”

It must have been pretty amazing to work for the legendary Harris corporation. Thanks for sharing!

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Hammarlund HQ series: A digital display modification

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Many thanks to SWLing Post reader, Jeff (KB7AIL), who shares the following:

Saw the article on the DC meter in a Hammerlund HQ180.

Another mod I have seen is replacing the meter with a digital display.

http://www.electronicspecialtyproducts.com/dd101.html

It integrates with the HQ180 nicely.

They also have digi-displays in cases or use with other receivers/transceivers.

Very cool, Jeff. While I know a digital display might kill the vintage look for some enthusiasts, I have to admire such a useful modification to replace a broken Hammarlund clock/meter.

As Jeff mentions, Electronic Specialty Products has a number of external digital display boxes as well. Check out their full line of products on the ESP website.

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Historic ‘Radio Row’ Finds a Home on the Internet

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(Source: 73 Radio Row press release)

A new website designed for radio amateurs, SWL’ers, CB’ers and all communications hobbyists has launched on the Internet recreating the atmosphere of the famed Radio Row in New York City.

According to its founder, Richard Fisher, KI6SN, “’73 Radio Row’ takes its cue from an era when New York’s legendary radio district bustled with communications fanatics shopping for surplus and used gear along Cortlandt Street in Lower Manhattan.” 73 Radio Row’s Web address is: http://www.73RadioRow.com

The site features used radio receivers, transmitters and transceivers, as well as unbuilt kits, new/old stock antennas, Morse instruments and station accessories of all kinds.

“We are crazy about radio, the same as everyone else,” Fisher said. “RETRO is NOWtro.” For complete details, visit: http://www.73RadioRow.com or write to: [email protected]. Call (951) 395-1923.

I discovered 73 Radio Row right after it launched–I ordered a portable ER TiCK Deluxe Keyer for the very affordable price of $26 US shipped.

The keyer was dispatched immediately and I received it within a couple of days.

I know Richard Fisher (KI6SN) quite well and can certainly vouch for his integrity. In fact, he’s even giving a portion of 73 Radio Row proceeds to Ears To Our World–what a nice guy!

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The new LNR Precision LD-11 transceiver is essentially general coverage

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A couple weeks ago, LNR Precision sent me their new LD-11 Digital Direct Conversion QRP transceiver on loan for review.

The LD-11 is basically a small, tabletop SDR transceiver. It’s like a miniature, simplified version of the Icom IC-7300 I’ve also been evaluating.

The LD-11 is an all-mode and all-band transceiver–meaning, it includes SSB, CW, CW-R, Digi, AM and FM modes on all amateur radio bands (160 – 10 meters).

Though the LD-11 isn’t advertised as having a general coverage receiver, it will indeed tune the entire HF band.

You do this by entering the LD-11’s administration mode. LNR describes this in the LD-11 product manual, but suggests you contact them for help the first time you do this. In the admin panel, you’ll find functions that allow you to set the band edges on each amateur radio band.

For a preliminary test of broadcast reception, I moved the lower band edge of the 30 meter ham radio band to 8.2 MHz.

After saving the settings and re-starting the LD-11 in normal operation mode, I could then tune the entire 31 meter broadcast band on the LD-11.

Hypothetically, you could either widen each amateur radio band to include adjacent broadcast bands, or you could simply set one of the ham bands to include the entire HF spectrum. To make it easier to navigate and tune through the bands, I’m choosing the former method over the latter.

Since the LD-11 has a proper AM mode, broadcasts sound great–especially via headphones!

Proper AM filters for broadcast reception!

Better yet? The AM filter width can be widened to an impressive 9.6 kHz! Woo hoo!

The LD-11 has four filter slots: F1, F2, F3 and F4.

The F1-F3 slots can be set to a fixed user-defined widths (common widths are default).

F4 can be altered to any available filter width without having to enter the admin mode of the transceiver. Simply press the “F” (blue function button) and the FILTER button simultaneously and use the encoder/tuning knob to specify the filter width in .1 kHz steps. Pressing the F and FILTER button simultaneously again, will save your filter width for the F4 position.

I’ve been using the F4 filter position for widths between about 8.2 and 9.6 kHz in AM.

It’s still early days with the LD-11, but I’m enjoying this little transceiver immensely. It reminds me of one of my favorite QRP transceivers of yesteryear: the Index Labs QRP Plus (though the LD-11 is much smaller, more versatile and has a much better front end than the QRP Plus!).

LNR Precision sold out all of their first run LD-11 units within moments of having announced availability. I’m willing to bet they’ll bring a few LD-11s to the upcoming Dayton Hamvention, though.

Check inventory status and view LD-11 details on LNR Precision’s website.

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Off-Grid Radio: Portable power recommendations?

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This year, I have a lot of portable radio play in mind as I travel across the continent. At some point, I even plan to spend several days in an off-grid cabin on the coast.

In the past, I’ve powered my 12 VDC ham radio transceivers with a system comprised of three PowerFilm solar 5 watt foldable PV panels (see below), a Micro M+ charge controller and several gel cell type sealed batteries (a couple 7 Ah and one 20 Ah).

The system works well, but the batteries are a little heavy and unhandy when I want to hike into a remote site or play radio on the beach, for example.

In terms of receivers, my portables (like the Sony ICF-SW7600GR, Tecsun PL-660, etc.) simply use AA batteries which I charge with PowerFilm AA PV chargers (see above). My CommRadio CR-1a has an internal battery that will power it for hours at a time.

Power is much less of an issue with receivers because they’re quite resource efficient.

I mainly need a system to power my QRP ham radio gear, and that’s where I could use your experience!

Wish list

Charge controller

I need a new charge controller since my Micro M+ (no longer produced) is now being used to power a remote antenna tuner.

Of course, I’ll need an inexpensive charge controller that doesn’t produce RFI (radio interference).

It would be an added bonus if the charge controller could also charge my batteries when grid power is available.

12 VDC Battery packs

I’d like something relatively lightweight and safe.

Note: LiPo packs worry me, especially since I had one (an early GoalZero model) quite literally melt down and burn up on my bed only a few hours after bringing it back from an eight hour flight a few years ago. Scary!

Pure Sine Wave Inverter

I’d also like a small, efficient pure sine wave inverter that I I could connect to my largest battery and power my laptop for extended SDR spectrum recording sessions while off-grid.

I’d love a recommendation from someone who uses one and can confirm a model that doesn’t create radio interference while operating.

Recommendations?

Post readers: Please comment with your recommendations and include model numbers and links if possible. Thank you in advance!

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The Icom IC-7300 vs. Elecraft KX3: Which do you prefer for CW/SSB?

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[UPDATE: Read the full review of the IC-7300, along with listener survey results, by clicking here.]

Many thanks to all of you who participated in our last survey comparing the new Icom IC-7300 with the WinRadio Excalibur SDR. We had over 100 responses (!!!)–the results will be posted in the forthcoming IC-7300 review.

Before completing my review, I thought I might fit in one more quick comparison–this time, comparing the Icom IC-7300 to my Elecraft KX3 and focusing on SSB and CW reception.

Recording notes and disclaimers

The Icom IC-7300 offers native digital audio recording, which means that it records both transmitted and received audio to an inserted SD card.

The Elecraft KX3 does not have a built-in recorder (indeed, most transceivers do not) thus I made in-line recordings using my Zoom H2N digital recorder.

I did no post-processing of the audio other than converting .wav files to .mp3.

Both receivers shared my large outdoor omni-directional horizontal delta loop antenna for each test.

The Elad ASA15 Antenna Splitter Amplifier

To keep the comparison on as equal footing as possible, the receivers shared the same antenna through my Elad ASA15 antenna splitter amplifier. Though the ASA15 has both 12dB amplification and –15dB attenuation, I employed neither.

The ASA15 allowed me to make the following recordings simultaneously.

In each case, I tried to set up both radios using the same filter widths, AGC settings, and (as much as possible), audio level. I didn’t engage a noise-reduction feature on either rig.

I also didn’t employ any type of audio equalization on either rig–still, you’ll note that one radio produces a more “flat” response than the other.

Please vote!

At the end of this post, I have an embedded a survey in which you can vote for the sample recordings you like best. Each recording is clearly labeled to denote that it’s either from “Radio A” or “Radio B” (chosen at random).

And now…here are the recordings:

Audio Clip 1: CW (20 meter band)

Radio A

Radio B

Audio Clip 2: Weak Signal CW (20 meter band)

Radio A

Rado B

Audio Clip 3: Weak/Strong SSB
(Sable Island working Asia/Pacific on 20 meter band)

Radio A

Radio B

We want to hear from you!

Use the form below to vote for the recordings you prefer in each section.

I’ll close voting at 12:00 UTC on Wednesday April 27, 2016. Thank you in advance for your participation in this survey!
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Video: SDR Touch demo on Android device using SDRplay RSP

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(Source: SDRplay via YouTube)

Click here to view on YouTube.

This demonstrates turning an Android Tablet (or Android Phone) into a highly portable comms receiver or spectrum analyzer operating from Long Wave to Microwave (10kHz to 2GHz) – using SDR Touch and the SDRplay RSP www.sdrplay.com

To be a beta tester simply go to https://play.google.com/apps/testing/ and follow the instructions – the SDR Touch author welcomes feedback on https://www.facebook.com/SdrTouch/ – your chance to influence the way this amazing software can get better and better.

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