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Details about  Drake FS-4 Frequency Synthesizer For SPR-4 or R-4 Receivers

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Drake FS-4 Frequency Synthesizer For SPR-4 or R-4 Receivers
Item Sold
Item condition:
Nov 13, 2011
US $479.99
$20.40 Economy Shipping | See details
Item location:
Lamar, Pennsylvania, United States


eBay item number:
Seller assumes all responsibility for this listing.
Last updated on  Nov 06, 2011 06:57:20 PST  View all revisions

Item specifics

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This item is a scarce Drake FS-4 frequency synthesizer used by many pieces of RL Drake equipment manufactured in the 70s and early 80s.  It was used by me personally with my Drake SPR-4 for a number of years and I am downsizing my receivers due to financial need.

During the time of manufacture in the 70's, many of the Drake receivers were crystal controlled and the user was limited to about 500 khz within each crystal range.  Because the receivers had a limit on the number of crystals that they could use within the receiver, the Drake receivers were not general coverage and the owner had to prioritize which bands they wanted to be able to tune into and sacrifice listening in on other bands.

However, Drake also offered the FS-4 frequency synthesizer for sale and this allowed for general coverage on many of it's receivers.  As I recall, the original cost for this unit was around $250 or so making it quite an expensive accessory item at the time when the receiver sold for about $400 to $700.  This explains why the production was limited and why these FS-4 units are not that common.  For this reason, I have set the price to reflect this scarcity.  If it does not meet with your desired price, I will be further reducing the FS-4 price periodically until sold.

The unit was specifically designed to interface with the "4" series of receivers like the SPR-4, the R4-C, and the T-4X. (R-4, R-4A, R-4B, R-4C. SPR-4, T-4, T-4X, T-4XB and T-4XC) For example, with the SPR-4 receiver, the operator can tune from 500 khz on up to 30 mhz.  The frequency on the FS-4 in Mhz is added to the frequency on the PTO in Khz for the proper frequency reading. Thus, if the FS-4 reads 3.5 Mhz and the PTO reads 450 Khz, the frequency being received is 3.950 Mhz.

The FS-4 provides the proper injection signal using a cable that connects into one of the crystal sockets.  The center of the coaxial cable plugs into the socket and the shielding fastens to the chassis of the receiver.  When I used this cable on my SPR-4, there was a nearby screw to attach the shielding so this connection was a snap to accomplish.  There is also a grommet attached to the cable to allow for a professional look after installation.

While not designed specifically for the "2" series receivers, the FS-4 will work with it.  However, it is not full coverage as you have to add 7 mhz to the scale and this makes the FS-4 usable from 7 - 30 mhz on the "2" series units.  You also may need to exchange the crystal inside the FS-4 with another one that is available online, but my experience has been that the calibration travel on the units generally allows for you to use the crystal as installed.

Here is information found at the Drake site regarding this unit:


The FS-4 comes with a copy of the manual that contains connection information, operating instructions, and a schematic.  I have also burned this info onto a CD that will be included along with the unit.  The FS-4 comes with it's injection cable and this is unusual as they are typically missing when sold on the used market.

The FS-4 is in good, but not perfect condition.  While it has been used with my SPR-4 and works beautifully and without any issues, the case does show some scratches.  This is common with these FS-4 units and obviously does not affect performance.  Please look at the pictures for the cosmetic detail.

At this point, I am happy to try to answer any questions.  The FS-4 will be packed to for good protection of the unit.  Those living in the USA may use the Ebay calculator for shipping cost.

Those living outside the USA are also welcome to purchase this unit.  I have had a lot of good experiences meeting buyers overseas and helping them receive equipment made here in America.  You may use the Ebay calculator for your shipping cost.

Please keep in mind that my shipping quote does not cover any import, duty, or VAT fees.  You will need to contact your local custom's office to determine the cost of additional VAT or import charges, if any.

The buyer may pay via cash upon pickup or with Paypal.  Paypal payments are expected within 3 days.  Ebay does not permit us to list other accepted forms of payment so I will refrain from doing so as I do not want them to remove my listing as is the Ebay policy.  Please email if you have any questions.

Penna residents are reminded of their responsibility regarding the 6% state sales tax.

Thank you for taking the time out of a busy day to visit my Ebay items!

SquareTrade © squaretrade warranty v2.0

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