[Heath] Fw: Heathkit SB-610

[Dick KF4NS]

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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