[AMRadio] Sommerkamp FR100B Receiver

Wed Nov 23 21:41:09 EST 2011

Paul, Thank you for the detailed email about this receiver.  Mine is in good shape physically and has a clean chassis. Of course it is not museam quality, but it is not bad. I bought this receiver with a Johnson Viking transmitter, and a Hallicrafters receiver, I forget which one.  The Hallicrafters is not in very good condition. I paid $50 for all of it. The Viking is not in bad shape either. I will have to look into the mechanical filter. When you removed the old foam, did you replace it?The first order of business will be to order a set of tubes and caps, while I am waiting on those itmes I can look into the mechanical filter. Thanks again, 73Mark
 > From: w9ac at arrl.net
> To: amradio at mailman.qth.net
> Date: Wed, 23 Nov 2011 19:17:20 -0500
> Subject: Re: [AMRadio] Sommerkamp FR100B Receiver
> 
> Mark,
> 
> I spent the better part of last spring restoring one.  It took six (6) 
> FR-100B receivers in various condition, collected over a 15 year period to 
> get just one unit restored to the point of being "as new."  There are 
> relatively few caps to change and most are available from Antique Electronic 
> Supply.
> 
> For those not familiar with the FR-100B, it's the receiver used in the 
> now-famous JA1MP QSL card showing Yaesu founder, Sako Hasagawa at the 
> controls of an early "F" line (ca. 1965). The card was issued in the 
> mid-'90s to commemorate the release of the FT-1000MP.  Hasagawa and Wolfgang 
> Sommerkamp teamed up in the '60s to market and re-brand the Yaesu product 
> line in Europe.  The only difference between the two brands of FR-100B is 
> the front panel moniker.
> 
> There are several electrical variations of the receiver -- some 
> significantly different and you'll need to acquire the right schematic. For 
> example, the early FR-100B breaks the C.T. of the HV transformer secondary 
> to put the Rx in standby.  It's horrendous.  Shortly afterwards, Yaesu 
> developed a better AGC bus and re-established the C.T. connection.  Another 
> difference is that the VFO mechanics  are different among variants.  The 
> FR-100B uses a 6BM8 and a NE-2 neon bulb to form a 100v regulator.  Never 
> seen that before but regulation is excellent once all the faults are 
> cleared.
> 
> There are many similarities between the FR-100B and Collins 75S.  Clearly, 
> Hasagawa had copied many of the same S/Line design concepts into the F line. 
> The FR-100B uses a Kokusai 455 kHz mechanical filter.  If the receiver seems 
> extremely dead, be prepared to completely restore the filter.  It requires 
> disassembly of the filter module and clearing out decomposed foam from the 
> ceramic tuning discs.  The rotted foam forms a mechanical 'short" across the 
> discs.  It's about a three hour job to do it right.  But after cleaning? 
> Wow, what huge difference.  I never would have believed that a ca. 1960s 
> tube Rx would have too much gain and sensitivity on 10m.  This one does when 
> the filter is working properly.
> 
> The AF stages will need modification.  But it's easy  Hasagawa decided to 
> route the headphones from 1/2 of a 12AT7 through a 0.05uF disc cap through a 
> normally-closed (NC) headphone jack, then feed the NC pin to a 6AQ5 class-A 
> power amp.  Modern 8-32 ohm headphones don't do well being coupled by 0.05 
> uF of capacitance.  I used the same technique used in the Drake R-4B. 
> Namely, re-wiring the jack after the 6AQ5.  Now, tons of gain into low-Z 
> phones.
> 
> The FR-100B user experience in the '60s must have been very much like owning 
> a 75S.  The front panel consists of thick sheet of anodized aluminum, 
> engraved and filled.  I absolutely love that look and I've copied it into my 
> own panel designs.  The Rx is very roomy like a 75S and alignment is 
> straight-forward.  Also, the BFO crystals have a tendency to drift a bit 
> such that the audio passband on one sideband may sound "thinner" than the 
> other.  Unfortunately, the xtal circuit will not allow crystal bending. 
> Boy, I tried several methods and in the end its best to order a set of BFO 
> crystals through JAN, ICM, etc, if necessary
> 
> Just be aware that the odds are not in your favor of the receiver being 
> functional.  It will be almost imperative to clean the mechanical filter. 
> I've only found perhaps one in ten that was working without significant IF 
> path loss.  I don't want to scare you off about my collection of 6 
> receivers.  I wanted to create a museum piece using the best parts from the 
> carcasses I had collected.  The cabinets are being carefully painted this 
> week and I hope to soon show the FR-100B and FL-200B on my QRZ.com page.
> 
> I think the FR-100B is historically significant.  For better or worse, it 
> was the product that laid the foundation toward the obliteration of U.S. 
> manufacturers.  From the FR-100B came the FR-50, then the FTdx series, 
> FT-101...and the rest is history.
> 
> Paul, W9AC
> 
> 
> ----- Original Message ----- 
> From: "mark depaepe " <n5yey at live.com>
> To: <amradio at mailman.qth.net>
> Sent: Wednesday, November 23, 2011 4:26 PM
> Subject: [AMRadio] Sommerkamp FR100B Receiver
> 
> 
> > Hello all,
> >
> > I recently picked up a Sommerkamp FR100B receiver. It has been in storage 
> > for years so it will need some work to get it into a usable condition. 
> > Does anyone have a schematic or service manual or know where I can find 
> > one?
> > I have never seen one of these radios before. Does anyone have any 
> > experience with this receiver?  Is it worth repairing?
> >
> > 73
> > Mark
> > Sent from my Verizon Wireless BlackBerry
> >
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