"Gene McCalmont" <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- Hello John; Your post caught my eye this afternoon, so I thought I'd share my experience with you while the Redskins get trounced by the Giants in the background.
The first question you should ask yourself is "What do I intend to do with this once I'm finished?" Not all of the modifications from Sherwood are needed if you intend to operate only CW or only SSB or listen only to AM. Also, I'd ask "What is reasonable for me to spend?" A "full boat" R-4C can be an expensive proposition. I know, I've built 6 of these machines for myself and for others. They are remarkable receivers and perform very well when compared with more modern rigs. I'd also ask myself "what level of performance do I expect?" That is to say, a R-4C with the appropriate 2nd IF filters and the installation of the "GUF-1" upgrade 1st IF filter from INRAD, produces an excellent receiver with not a lot of investment. I'd suggest the 6Khz crystal filter if your operation is mostly CW/SSB. If you use your radio to listen to SW broadcast, then the 8Khz filter would be a better choice. If you have installed the 4NB, then the 8Khz filter is again your best choice. It allows the noise blanker to perform it's job better, with less pumping of the AGC. One of the most popular and biggest bang for the buck mods from Sherwood is the upgrade power supply board and the R-4C audio amplifier, AMP-4. These modifications solve two of the most annoying problems of the rig. The Sherwood web site explains the upgrades in good detail. These mods are relatively easy to perform and your cash outlay is less than $100. Everything gets progressively more complex and expensive from this point onward. I almost always replace the diode product detector in an upgraded RC-4 with the Sherwood PD-4. It gives the receiver improved headroom in the presence of strong signals. It's more difficult to install, in my opinion, but still well within the capability of most Hams. You must pay close attention to the instructions and be able to identify various components on the Drake factory circuit boards. The MIX-4 is the last upgrade I do, but only when the particular R-4C I'm working on is having problems in this area. A problematic 3rd mixer presents a noticeable hum in the audio and the typical "snap crackle pop" of a noisy 6EJ7. It is one of the more difficult mods to install. Since 6EJ7s are cheap and plentiful, I first try to find a tube that will solve the problem before resorting to the MIX-4 upgrade. Last but certainly not least are the first IF crystal filter upgrades. This is where you are going to spend a lot of money but the results are very dramatic. If operating CW exclusively, or just "a lot", the 600hz crystal filter will DRAMATICALLY improve the receiver's ability to isolate individual signals and gives the CW operator a truly superior machine. It is difficult to describe how unwanted signals just disappear when the 600Hz is switched into the IF chain. The upper and lower SSB filters dramatically improve the receivers 3rd order intercept performance with a resultant improvement in MDS in crowded band conditions. There are few receivers that offer the kind of performance these filters bring to the R-4C. The "roofing" filter approach is one of the reasons the TenTec Orion has won such acclaim for it's performance. However, installation of the filters and attendant switching circuits is not for the faint of heart. I hope this information helps out some, John. Perhaps others have differing opinions worth considering. Best regards; Gene W5DDW Gene McCalmont 270 Oak Ridge Ln. Argyle Texas 76226 ---------------------------------------------------------------------- On Behalf of "Gene McCalmont" <[EMAIL PROTECTED]> Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
