Fox Tango International

 presents the Yaesu FRG-7

 

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The FRG-7 is an all solid state synthesized communications receiver designed to cover 500 KHz to 29.9 MHz.  The FRG-7 is a triple conversion super heterodyne receiver utilizing the Wadley Loop System which uses a  harmonic generator that  is based on a 1 MHz crystal oscillator which produces a signal at 1 MHz intervals. The late Dr. Trevor Lloyd Wadley was one of South Africa's most famous electrical scientists. He was born in 1920 and died on the 21st May 1981.

Yaesu Musen FRG-7

 Communications Receiver

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Sears, Roebuck Co. Version of the FRG-7

This version came in a black case

 

 

$299.50 U.S Dollars in 1977

Original Sears, Roebuck & Co. Advertisement

Fall / Winter 1977 Catalog for the (Yaesu) Sears Communications Receiver.

 

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Yaesu made several pieces of equipment  which were sold  by Sears and Roebuck in the mid to late 1970's.

 

 

 

 

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Click for larger view.The Sears version of this receiver had a black case where as the original FRG-7 sold to the amateur market was in the traditional Yaesu gray. For those of you outside of the United States, Sears & Roebuck Co. is one of America's largest department stores and dates back into the late 1800's. http://www.bgsu.edu/departments/acs/1890s/sears/sears4.html

 

 

 

 

Sommerkamp FRG-7 It's still a frog!

For all practical purposes the Sears version of the FRG-7 was  100% Yaesu inside and out, except for the different name tag on front. Similar to that of the SOMMERKAMP label you find distributed throughout Europe, the FRG-7 was also sold under the Sommerkamp name.

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Even to this day the Yaesu FRG-7 is still considered to be a fine communications receiver and  performs well.  At the time it was a good buy for the money and made for a nice desk top general coverage communications receiver.  The receiver was reasonably priced and sold in the $300 USD range. When this receiver was in its prime, amateur radio transceivers did not come fully equipped with a general coverage receiver built in like today's modern rigs do. So it was a nice optional piece of equipment to have in one's station in the mid to late 1970s ham shack. Even today however it is still sought after and  a pleasure to operate, Yaesu collectors like it because it matches the entire Yaesu FT-101 / FR-101 / FL-101 / FL-1000B series of amateur equipment perfectly. Modifications such as the Kiwa filter switch board modifications and the addition of a 100 KHz calibrator can bring your FRG-7 running as good as most modern communications receivers.


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While it's really nice knowing the exact frequency you are on down to 10 Hz or so when using a modern receiver, it's really not necessary to have that kind of accuracy for general coverage listening.  When using an older receiver such as the FRG-7 the analog tuning can prove to be an asset while cruising the international short wave bands as some of the more modern digital receivers have an annoying pop on and off as you turn the dial up and down the band. You don't have that problem with an analog (Non-digital) receiver like the Yaesu FRG-7 receiver.  Considering a bandwidth of +6Kc  when listening to international short wave and local AM broadcast you really don't need the digital accuracy past 1kc readout along with all the fancy digital features of a modern receiver as they are seldom if ever needed.

Kiwa Filter Switch Board modification    

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Above you can see the original blue Yaesu I.F. Filter center.

 

Kiwa Electronics offers a Mini-Filter Switch board that you can install to replace the original stock I.F. band pass wide FRG-7 filter.  Above you can see the Kiwa filter modification installed, it provides two bandwidths. The wide bandwidth is 6.2 kHz. This is an excellent bandwidth for general listening while providing excellent fidelity. The narrow bandwidth is 3.7 kHz. This bandwidth provides the necessary selectivity for single side band listening, weak or difficult signal conditions.  A toggle switch will have to be  mounted to the rear chassis, this will  provide filter selection as seen in the photo below.

 

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The Kiwa Filter Mod Can be obtained from Kiwa.com

 

Finding your FRG-7

The FRG-7 receiver can still be found today from various price ranges from $100 USD to as much as $400 depending on the condition of the receiver.  If you're going to buy on E-Bay (Don't get me wrong I like E-bay) just be careful and know what it is you're buying.  Ask the seller plenty of questions before buying your receiver and if they don't answer you, then I recommend you don't buy from that seller.  Below you can click on some pictures of an FRG-7 overhaul job that I did.  I purchased this receiver off Ebay and it arrived at my door step with eight "D" cell batteries bouncing around inside it loose and the batteries were leaking acid every where. It was a real mess! I was told it was in good condition and working.  It looked like it sat in a barn for the last 25 years and the Ebay seller later bought it at a garage sale for little or nothing hoping to dump it on Ebay for a maximum cash return.   When I got the receiver it had a big gash across the front speaker grill and was literally filled with dirt. You might enjoy thumbing through these photos below.

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Even after many years and owning several of these receivers, I still find that the FRG7 performs as well if not better then many of the newer digital receivers on the market today even with all their bells and whistles.  I still enjoy using the FRG7 because it can ROLL through an entire chunk of the H.F. spectrum (1 MHz) of the band by just spinning the dial when looking around for activity across the bands.  I have found that many newer digital receivers  (I also own a Sangean ATS-909) just do not have the operating ease when cruising the band like my old reliable FROG!

 

  Finding another Oldie but goodie!

8/14/05 Having recently picked up another  FRG-7 that had not been used in some period of time. It was indeed in need of some maintenance.  The receiver had a real bad case of loss in front end sensitivity. Little or no signal indication on the signal meter and no ability to peak the front end of the receiver with the preselector tuning control. If you have this problem it is a good indication that your Front End FET Q-101 (3SK40) has bit the dust.  Suggested replacement NTE-454    Replaced Q-101 and the receiver basically started to come back to life.  In the case of the Yaesu FT-101 amateur transceiver, it was later recommended by Fox Tango members to replace the 3SK40 front end FET with a 3N211 MOSFET that was internally diode protected from static discharge on the antenna and less likely to blow out.  An added advantage of the 3N211 was slightly higher receiver gain.  Due to the fact that the 3N211 is no longer available the current replacement part is an NTE-454, N-channel,

SEE: http://www.nteinc.com/specs/400to499/NTE454.html

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Upon restoring the front end back to normal, I found it difficult to find any stations where they were suppose to be on the dials.  Now its really hard to say why the receiver wound up in this condition, but the MHz indicator was 1 full Mega Hertz off from where it should have been. I can only assume that someone got into the receiver with a golden screwdriver.

 

Click for larger view.Looking for amateur activity on 3.900 KHz and at night there should be plenty of it to be found. I heard nothing. Finally tuning the MHZ control up to 4 MHz all the amateur activity on the upper end of the 75 meter phone band 3.800 KHz and above came to life. Hummmm, maybe we have got a mechanical problem with the MHz tuning dial?  At least this was the first thought to go through my mind.  A quick glance on the schematic reveals the oscillator unit (PB-1523) and T201.

 

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Turning / tuning T201 would do just about the same thing as tuning the front panel MHZ control.  Thus I put the MHZ control on 3 MHZ as it should have shown in the first place. Took a very small screw driver and tuned T201 until I head the amateur activity again on the upper end of 75 Meters pop back in and then tuned T201 just a little further until the RED lock lamp was extinguished.  Tada.. all frequencies now line up properly.  Along with the new front end FET, the receiver appears to be and running again as good as new.

 

Also suggest your  putting a small 12v peanut bulb in behind the meter to brighten up the meter while you have the receiver open. In the left photo you can see the meter without illumination, in the center we have the meter with a new lamp and in on the right you can see the lamp in behind the meter. I highly recommend you connect your lamp up to the dropping resistor as per where the other receiver lamps are connected. You don't want the lamp so bright and hot that it would melt the plastic meter case.

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Adding a 100 KHz Marker Generator

to your FRG-7 Receiver

While many early amateur receivers work just fine they usually lack a digital readout and must rely on analog dials for tuning.  The problem of dial calibration is complicated by the non-linear effects of tuning capacitors.  A nice addition to the FRG-7 analog receiver is the addition of a 100 KHz marker generator (Oscillator).  Unfortunately the FRG-7 did not come with this feature but it's an easy add on if you have the oscillator to do the job.  The oscillator I used came from an older tube type Yaesu amateur transceiver.  Having an old FT-200 / Tempo One in the junk pile I decided to put the old crystal calibrator board (PB-1068) to use.  The board made for a perfect addition to the FRG-7 and did a nice job, (PB-1068) uses the old style 100 KHz HC/13Uw crystal and for the oscillator transistor.  If you're looking for one of these oscillators, check with us as we do get them from time to time.

 

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Installation of PB-1068 in the FRG-7 Communications receiver requires only two wires, one for 9 Vdc and a signal output.  It is recommended that you run the output of the crystal oscillator directly into the SO-239 antenna connector on the rear of your transceiver.  After experimenting a bit trying to find the best place to inject the oscillator signal, we have found this to be the best bet overall.

 

 

 

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White wire, 100 KHz signal injected into RF Amp at VC1, but better if you just run this wire to the SO-239 antenna input.

 

Pick up the 9 Volt DC for you oscillator at TP-406 on the AF unit. See RED wire in photo to the left.

 

 

 

 

 

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Installing a small switch at the rear panel to turn the oscillator on and off, this way you do not deface the front panel.

The oscillator yields a +20db signal every 100 KHz as expected.

 

 

 

 

 

 

 

Free FRG-7 manual Zipped (PDF) Downloadable file

 Yaesu FRG-7 Communications Receiver Owners and Maintenance Manual (Zip)

 


 

 

 

If you are interested in learning more about  shortwave listening and the Yaesu FRG-7

 I also recommend you join the on line Yahoo Forum for discussing the  "FROG" FRG-7

 

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Carol L. Maher W4CLM

Administrator Fox Tango International