[Heathkit] Fw: [Heath] Heathkit SB-610

Wed Mar 7 15:28:14 EST 2012

Years ago when I tried to connect my SB-610 to my Kenwood R599D receiver
(output of the last IF) to view dancing audio, I couldn't get enough
signal into the SB-610. I built a simple 3 or 4 transistor voltage
amplifier (used some cheap switching transistors) on some perf board to
pump up the signal to drive the SB-610. I mounted it under the chassis of
the R599D with some double-sided tape. Still works fine 25 years.

Pete, wa2cwa

On Wed, 07 Mar 2012 14:43:17 -0500 "Dick KF4NS" <kf4nsradio at verizon.net>
writes:
> Ok guys, most responses have been related to the coax. Since there is 
> no loss in the 610 and the vert amp 
> is doing its job the loss is obviously in the originating equipment. 
> Also, Heath does not say you should 
> use RG-62, it only mentions the best coax for the xmit input/output. 
> There they say to use 50 or 75 ohm 
> coax.
> 
> I was doing some thinking (bad for someone my age) and remembering 
> electronics school, as I recall 
> capacitors in series are equal to a value lower than the lowest 
> capacitance. (smaller than the smallest 
> as I remember) so my 5uuf cap in series with the 93ohm coax should 
> result in total capacitance less than 
> the 5uuf cap in series.
> 
> Hmmmm! Is my age showing or am I thinking correctly. Some have said 
> they use all different types of coax 
> with no trouble. What if I used just a piece of insulated wire from 
> the 2nd IF to the jack on the xcvr 
> back and use coax from there to the 610 ?
> 
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> Keep The Glow!
> 
> 
> ----- Original Message ----- 
> From: <ma.locksmith at juno.com>
> To: <kf4nsradio at verizon.net>
> Sent: Tuesday, March 06, 2012 6:52 PM
> Subject: Re: [Heath] Heathkit SB-610
> 
> 
> | Yes, the coax IS faulty....  but, not because it's broken
> |
> | You have selected wiring with very high capacitance.  This makes 
> a
> | capacitive divider for the signal.  If you only have 5 pF 
> capacitance in
> | the cable, you have a 2:1 reduction in signal strength.
> |
> | RG174 and RG58 have high values.  I think the 58 is 32 pF per 
> foot.  Not
> | sure about the 174 unless I look it up.
> |
> | I expect the "right" cable between the set and the 610 will be RG 
> 62.
> | And, more than likely, unshielded wire inside.
> |
> | Ed
> | K1ZOK
> |
> | On Tue, 06 Mar 2012 15:58:50 -0500 "Dick KF4NS" 
> <kf4nsradio at verizon.net>
> | writes:
> | > Looking for your input and recollection of what you did. I have 
> now
> | > completed a full restoration of my
> | > SB-610 and have concluded that the one remaining fault, low 
> vertical
> | > gain, may  be due to how I have
> | > connected it to my HW100.
> | >
> | > It did work pretty good at one time so now there is a bit of 
> head
> | > scratching. I  have no losses in the
> | > 610 and the vertical amp, when driven with a sig gen at 3395khz
> | > modulated at 50%, I see .4v (spec.
> | > recommends .5v input) at the grid and get 23v at the plate. 
> That
> | > sounds like the 610 is doing the job.
> | > The vertical gain pot is fine. So now I suspect it has to be 
> the
> | > connection to the rig.
> | >
> | > I used RG-174 in the HW100 from the second IF plate and have a 
> 5uuf
> | > cap in between. Outside the rig I
> | > have a short run of RG-58 to the 610. I can only see .1v from 
> the
> | > rig. The coax is not faulty nor is the
> | > capacitor.
> | >
> | > What did you use in your Heathkit rig for coax and coupling cap. 
> and
> | > what did you feed the 610 with? Did
> | > you connect to the first or second IF and at the control grid or 
> the
> | > plate? I did do a mod to the 100
> | > which lowers the IF gain to improve gain distribution. This 
> came
> | > from my friend Mark's (WB8JKR now SK)
> | > presentation for optimizing the HW/SB transceivers. When the 
> scope
> | > was working fairly good this mod was
> | > already there. I did realign the rig though at some point since
> | > then. The 100 is working great.
> | >
> | > Thanks and 73, Dick KF4NS
> | > St Petersburg, FL 33714 USA
> | > Keep The Glow!
> | >
> | > _______________________________________________
> | > Heath mailing list
> | > Heath at puck.nether.net
> | > https://puck.nether.net/mailman/listinfo/heath
> | >
> |
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