RF limited CR577 (2010)

Some time ago, I made a small review of the vintage Astatic 575M-6 ceramic teardrop hand microphone and report about the RF limited CR577 which seems to be a good modern version or copy if you prefer from the Astatic mic. I managed to get a CR577 mic in good shape to make a review aswell. The RF limited CR577 is almost as scarce as the original Astatic model. It seems that RF limited stopped the production of the CR577 and that owners from this mic are not ready to sell their RF limited mic, must be a good keeper one.

RF limited isn’t well known in Europe as the mics, rigs and others items made by this company are not well distributed here. I think very little people in Europe know that RF limited, Palomar, Magnum and others brand names belong to the same company.

If you search for RF limited on the net you’ll probably be crossing the others brand names and found that they all have the same address and the same boss. Below you can read what the boss said.


Our History – It’s all in the name. 

In the 1970’s when my grandfather, Sam I. Lewis, Sr., closed Palomar Electronics Corporation the name was unfortunately lost. Over the next 40+ years my father, Sam I. Lewis, Jr, carried on in the spirit of Palomar under the company name RF Limited. In 2000, I started EKL Components, a sister-company to RF Limited, dedicated to the component side of our industry.
From the beginning, it has been my goal to regain the name that my grandfather and father made famous – and that day is here. Palomar Electronics is now the new, original, name of RF Limited and EKL Components. Palomar will continue to use the brand names, such as Magnum, that everyone has come to know over the past 50 years.
I look forward to continuing on in the tradition of my grandfather and father to develop innovative and industry-changing products. Stay tuned.
Eric S. Lewis
President, Palomar Electronics

I found an interesting story about the RF limited CR577, you can read this story there:



After making some tests I found the CR577 to be a very good microphone and to my point of view, the copy is as good as the original if not better…

The loaded output is vastly sufficient for any rig on the market, the tone control is really efficient and everyone will found a position that matches needs.

I agree with the positive remarks in the story above, so I won’t make a copy of it but take time to made some measurements and audio files.


“Nutrition facts”

Year : 2010 (not vintage but good)
Type of microphone : Ceramic
Microphone characteristic : Semidirectional
Sensitivity : -60dB (given, more on that later)
Nominal output : not given as -60dB doesn’t mean anything
Measured output : 18mV
Max output : 200mV @ 1KHz @ 114dB (some audible distorsion)
Max output : 100mV @ 1KHz @ 111dB (free from audible distorsion)
Output at mid range : 10mV
Frequency response : 30Hz to 15000Hz (given)
Output impedance : not given
Measured output impedance : 5.1KOhm
Amplifier voltage gain : not given
Tonal control : Yes (very effective)
Compression : No information given
Meter : No
Echo : No
Lock switch : No
Tx LED : Yes (a red one)
Battery : 9V

Please note that the measured output value above will normally be given @ 1KHz and 600Ohm load @ 94dBSPL.

Remarks, -60db doesn’t mean anything as there is no indicated reference. Regarding my measurement I think RF limited use the old reference system (0dB=1Volt/microbar). -60dB (0dB=1Volt/microbar) is equivalent to -40dB (0dB=1Volt/Pa) the now used reference. This means that if you speak loud (not cry) in your microphone from about 2 inches a distance you should get 10mV @ 94dBSPL at the output of the microphone at the given load impedance (also not given but must be 600Ohm)… With the CR577 you have to speak loud and very close to the microphone. I though RF limited been honest given -60dB at supposed (0dB=1Volt/microbar) reference has I measure -35dB (0dB=1Volt/Pa). I measured an output impedance of 5.1KOhm.


My opinion, a very very good microphone with a cristal clear modulation tailored for ssb DX or the one who wants a powerfull AM or FM modulation. My exemplar doesn’t suffer from hum or other audio probs as sometimes reported, in fact, in absence of mod the mic is completely silent. Good construction, quality plastic and metal grid used for the front, screening inside. This mic is achieving a very effective noise reduction in an unusual way, as you have to speak very close to the element, the surrounding noise won’t be picked up.

Seen price:  70€ listed price (always out of stock HI), 80€ to 90€ or more on the Bay but very scarce.

My evaluation : Very good, very powerfull mobile microphone. The MP3 files doesn’t reflect the quality of this mic ON THE AIR, it’s much louder ON THE AIR but I’ve no expanation why.
5/5 rating

Listen to the sound of the RF limited CR577 volume at 10 tone at 0

Listen to the sound of the RF limited CR577 volume at 10 tone at 5

Listen to the sound of the RF limited CR577 volume at 10 tone at 10

Listen to the sound of the RF limited CR577 volume at 5 tone at 0

Listen to the sound of the RF limited CR577 volume at 5 tone at 5

Listen to the sound of the RF limited CR577 volume at 5 tone at 10

You will find below the tone correction (real world) I got using differents tone control positions. Blue line is tone control at 0, red line is tone control at 5 and green one is tone control at 10. Volume control at 5 each time.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s