[Drakelist] R4C 160 Meters Sensitivity
Hi Group Has anyone found a way to improve the sensitivity on the 160 Meter Band?? It seems less lively compared to the other bands even after alignment. Thanks in advance Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Interesting Find
My R4C seemed a bit poor in the sensitivity department so I had an idea to improve it. I aligned the R4C pretty well but it didn't seem very lively. So with the bottom chassis visible I took my screw driver and loosened/ tightend each screw twice on each side of the 4 rows of trimmer bracket ground. Wow.what a difference in sensitivity mainly 160-20M and in between. I estimate a 8-10 dB of more gain. I learned this method of re-establishing grounds from a metallurgist(sp)ham neighbor who showed me what happens to two surfaces create a fine film a lose bonding with time. If the two metals are much different the faster the degradation. Your mileage may vary. I recommend all accessible screws and nuts...it can cure some pretty obscure problems and takes less than 15 minutes. I had to recalibrate the S-meter because of the gain change. It should work on R4any receiveror any old boatanchor. Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C SSB Leakage
Hi Group I have written previously about my R4C having signal leakage in the SSB mode only affecting the PBT control and S-meter levels. Someone suggested that the 4NB was causing the leakage so I removed the 4NB and put some wire jumpers as I didn't have a 4NB plug, no change. However I ordered a aftermarket socket plug to do a sanity check..guess what..it got worse!!! Instead of a S5 level leakage it then went to S9 with the shorting plug??!! I guess I've narrowed it down to something on or near the NB4 jack underneath. So much for the sanity check..bizarre. Best 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Speaker Output
Hi Group On the R4C speaker output which is 3.2 ohms. Can this audio be attached to a computer's microphone jack (typically 50K) using a resistor pad to prevent overload?? 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Need R4C Xtals
I am stil looking to buy a few Stock R4C Xtals. Mine are way off frequency...they are: 7.0 Mhz (18.1 Mhz) 28.5 Mhz (39.6 Mhz) These are Stock R4 any Xtals so they aren't scarce. 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Static
I have noticed that when using narrow CW Filter's in my R4C that I hear low-moderate static bursts,like storm static. I have substituted each and all the 6EJ7's with new tubes.no change. I removed each and all 6EJ7 tubes and power it on with no change in the static. I remove the 6BA6 RF tube no change. My R4C has a SS power supply, SS Audio Brd, SS Product Det. Sounds like a electrolytic or a resistor going bad. Any suggestions?? The RF Gain being reduced lowers this static level. 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C BFO Leakage
A few weeks back I wrote about PBT levels in SSB/AM modes. It would change S-Meter levels depending on adjustment of the PBT. I ruled out the 4NB board by removing it..no change. However when I removed the bottom cover almost 6 S-Units of PB feedthrough were reduced and performance was enhanced with less white noise. Interesting to know the interference is being conducted by the metal bottom cover to key area's of the bottom chassis. Next I will attempt adding metal shields to isolate internal RF from conducting to nearby by circuits that are prone. Best 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C PBT Leakage
Hi Bob I think you hit it on the head. Also I'm suspect of the NB cable harness being draped above the 3rd mixer tube area. I only regret not having a low end Spectrum Analyzer to end this design anomaly and improve this situation. As suggested I need to disconnect the NB and short some NB socket pins as I don't have the NB shorting plug. I have many years RF experience in a factory setting doing just this for 200 watt VHF-UHF repeaters. It's not for the impatient and is a fascinating. The way my R4C is operating in AM, SSB and CW receive modes.each one has different S-Meter calibration from each other. Best 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Questions
Hi Group I recently obtained a Sherwood upgraded R4C (SN 22xxx), the only Sherwood upgrade it doesn't have is the 2K Upper Lower SSB filters. It performs very well but it has one oddity. When in SSB mode and the PBT is adjusted Upper Lower end of travel it varies the S-Meter from S6 middle center PBT to S1 either PBT endpoint. On CW using the 1.5Khz, 500Hz or 250Hz it works like it should or what I'm accustom to. I've corrected many small problems by treating grounds and filter sockets, tube sockets from the topsidebottom side next. It just seems like I'm getting allot of white noise or bleed through from somewhere to cause the SSB mode oddity. Question? How can it tell if this has the T7C version xfrmer?? These Sherwood upgrades were done 20+ yrs ago and this nice condition R4C has sat unused for many years. Perhaps all is typical as I don't have another to compare to. Best 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Xtals
Hi Group I am looking to replace out of spec xtals in my Drake R4C receiver. One's listed are 4-9 Khz off frequency. The * xtals are for 160M 10M are more a priority. Contact me off list @ wmarv...@charter.net Wanted: 1.5 Mhz 12.6 Mhz* 3.0 Mhz 14.1 Mhz 9.5 Mhz 20.1 Mhz 10.0 Mhz 21.1 Mhz 11.5 Mhz 22.6 Mhz 28.0 Mhz 39.1 Mhz* 28.5 Mhz 39.6 Mhz* Best Bill KB9IV ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Xtals
For the most part I have found the xtals...thanks Doug! Best 4th to All Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4B Shorted Mini Coax
Hello Group I am near completion reworking my R4B. In the process I used the manual resistance chart to validate all was OK before powering the rig just to be safe. During check out I found a Big Problem on the V3 pin 5, it was shorted to ground ..140 VDC !! I used the divide and conquer method to separate and rule out the Notch Filter Brd and the 2nd LO Brd .also T7. As I disconnected the two leads from the Notch Filter Brd Red/Wht Small Gray Coax the V3 pin 5 was no longer shorted. I checked the Small Grey coax, now disconnected, and its shorted to ground. I believe this small coax goes to the front panel ( T 8 ). I haven't yet located the T 8 connection but my question is this. Where can I find a source for the grey coax wire?? I plan on routing the coax the same as the original. Is the T 8 assembly difficult to remove? FYI I believe I found the source of the coax short..on the coax path is a body coax clamp (small) It's was crimped so hard that the coax is very very distorted..has probably cut-in the coax itself..located by the RF Gain Brd area. Thanks and 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4B Calibrator Buzz
Hello Group I have been working on my R4B that has Calibrator Buzz and intermitent low audio Hum. All tubes are now good and the SSB/Cw receive is very clean. I replaced the Bias Cap 8 uF no go. Any hints Best 73 Bill KB9IVV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
